1
FEBRUARY 2009
DSC-5995/11
©2009 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice.
IDT and the IDT logo are registered trademarks of Integrated Device Technology, Inc. The TeraSync is a trademark of Integrated Device Technology, Inc.
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
2.5 VOLT HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT CONFIGURATION
16,384 x 40, 32,768 x 40,
65,536 x 40, 131,072 x 40
IDT72T4088, IDT72T4098
IDT72T40108, IDT72T40118
FEATURES
••
••
•Choose among the following memory organizations:
IDT72T4088 ⎯⎯
⎯⎯
⎯16,384 x 40
IDT72T4098 ⎯⎯
⎯⎯
⎯32,768 x 40
IDT72T40108 ⎯⎯
⎯⎯
⎯65,536 x 40
IDT72T40118 ⎯⎯
⎯⎯
⎯131,072 x 40
• Up to 250MHz operating frequency or 10Gbps throughput in SDR mode
• Up to 110MHz operating frequency or 10Gbps throughput in DDR mode
•Users selectable input port to output port data rates, 500Mb/s
Data Rate
-DDR to DDR
-DDR to SDR
-SDR to DDR
-SDR to SDR
•User selectable HSTL or LVTTL I/Os
•Read Enable & Read Clock Echo outputs aid high speed operation
••
••
•2.5V LVTTL or 1.8V, 1.5V HSTL Port Selectable Input/Ouput voltage
••
••
•3.3V Input tolerant
•Mark & Retransmit, resets read pointer to user marked position
•Write Chip Select (WCS) input enables/disables Write
Operations
•Read Chip Select (RCS) synchronous to RCLK
•Programmable Almost-Empty and Almost-Full flags, each flag
FUNCTIONAL BLOCK DIAGRAM
can default to one of four preselected offsets
•Dedicated serial clock input for serial programming of flag offsets
•User selectable input and output port bus sizing
-x40 in to x40 out
-x40 in to x20 out
-x40 in to x10 out
-x20 in to x40 out
-x10 in to x40 out
•Auto power down minimizes standby power consumption
•Master Reset clears entire FIFO
•Partial Reset clears data, but retains programmable settings
•Empty and Full flags signal FIFO status
•Select IDT Standard timing (using EF and FF flags) or First
Word Fall Through timing (using OR and IR flags)
•Output enable puts data outputs into High-Impedance state
•JTAG port, provided for Boundary Scan function
•208 Ball Grid array (PBGA), 17mm x 17mm, 1mm pitch
•Easily expandable in depth and width
•Independent Read and Write Clocks (permit reading and writing
simultaneously)
•High-performance submicron CMOS technology
•Industrial temperature range (-40°°
°°
°C to +85°°
°°
°C) is available
••
••
•Green parts available, see ordering information
INPUT REGISTER
OUTPUT REGISTER
RAM ARRAY
16,384 x 40,
32,768 x 40
65,536 x 40
131,072 x 40
FLAG
LOGIC
FF/IR
PAF
EF/OR
PAE
READ POINTER
READ
CONTROL
LOGIC
WRITE CONTROL
LOGIC
WRITE POINTER
RESET
LOGIC
WEN WCLK
D0 -Dn (x40, x20, x10) SREN
MRS
REN
RCLK
OE
Q0 -Qn (x40, x20, x10)
OFFSET REGISTER
PRS
FWFT
SEN
RT
5995 drw01
BUS
CONFIGURATION
OW
FSEL0
FSEL1
IW
MARK
SCLK
RCS
JTAG CONTROL
(BOUNDARY SCAN)
TCK
TMS
TDO
TDI
TRST
RSDR
WCS
ERCLK
EREN
HSTL I/0
CONTROL
Vref
HSTL
BM
WSDR
SI
SO
2
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
A
B
C
D
E
F
G
H
J
K
L
M
N
P
R
T
V
CC
V
CC
D34
D35
D30
TCK
WCLK
D24
D25
V
CC
V
CC
V
REF
D2
GND
D7
Q4
GND
Q0
GND
Q3 V
DDQ
GND
Q7
D13
Q5D1
GND
D4
D10
D15
FSEL0
D17
Q9 V
DDQ
Q23
Q28
REN
RCLK
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
A1 BALL PAD CORNER
MARK
RCS
V
DDQ
V
DDQ
V
DDQ
V
DDQ
GND
GND
GND
GND
GND
GND
GND
GND GND
GND
GND
GND
GND
GND
GND
GND
GNDD5
PRS
OW
D29
D26
D18
D19
Q1
Q2
EF
/
OR
V
DDQ
WEN
MRS
IW
WSDR
D27
D23
D37
D32
TDI
TMS
FWFT
WCS
BM
FSEL1
RSDR
D28
D20
D21
D22
D11
Q37
Q39
V
DDQ
SI
SREN
EREN
ERCLK
Q31
Q34
Q18 Q16 Q14 V
DDQ
Q10Q12
Q6 Q22Q8
D31
TRST
TDO
PAF
FF/IR
D36 D39 D8
V
CC
D3 V
CC
D6 V
DDQ
GND V
DDQ
GND Q21V
DDQ
Q20V
DDQ
V
CC
V
CC
V
CC
V
CC
V
DDQ
GND V
DDQ
GND Q26V
DDQ
Q27V
DDQ
GND
GND
GND
V
DDQ
V
DDQ
V
DDQ
Q13
V
DDQ
V
DDQ
GND
GND
D16 D12
D14 Q19 Q15Q17 Q11 Q38
SEN
SO
PAE
Q30
Q33
Q36
Q29
RT
OE
SCLK
GND
V
DDQ
V
DDQ
V
DDQ
GND
V
CC
V
CC
V
CC
V
CC
V
CC
V
CC
V
CC
V
DDQ
GND V
DDQ
GND V
DDQ
GND V
CC
V
CC
V
CC
V
DDQ
GND V
DDQ
GND V
DDQ
Q35
Q32
D38
Q24
Q25D33
HSTL GND
D9 GND
D0
5995 drw02
PBGA: 1mm pitch, 17mm x 17mm (BB208-1, order code: BB)
TOP VIEW
PIN CONFIGURATIONS
3
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
DESCRIPTION
The IDT72T4088/72T4098/72T40108/72T40118 are exceptionally deep,
extremely high speed, CMOS First-In-First-Out (FIFO) memories with the ability
to read and write data on both rising and falling edges of clock. The device has
a flexible x40/x20/x10 Bus-Matching mode and the option to select single or
double data rates for input and output ports. These FIFOs offer several key user
benefits:
•Flexible x40/x20/x10 Bus-Matching on both read and write ports
•Ability to read and write on both rising and falling edges of a clock
•User selectable Single or Double Data Rate of input and output ports
•A user selectable MARK location for retransmit
•User selectable I/O structure for HSTL or LVTTL
•The first word data latency period, from the time the first word is written to
an empty FIFO to the time it can be read, is fixed and short.
•High density offerings up to 5Mbit
•10Gbps throughput
Bus-Matching Double Data Rate FIFOs are particularly appropriate for
network, video, telecommunications, data communications and other applica-
tions that require fast data transfer on both rising and falling edges of the clock.
This is a great alternative to increasing data rate without extending the width of
the bus or the speed of the device. They are also effective in applications that
need to buffer large amounts of data and match buses of unequal sizes.
Each FIFO has a data input port (Dn) and a data output port (Qn), both of
which can assume either a 40-bit, 20-bit, or a 10-bit width as determined by the
state of external control pins Input Width (IW), Output Width (OW), and Bus-
Matching (BM) pin during the Master Reset cycle.
The input port is controlled by a Write Clock (WCLK) input and a Write Enable
(WEN) input. Data present on the Dn data inputs can be written into the FIFO
on every rising and falling edge of WCLK when WEN is asserted and Write
Single Data Rate (WSDR) pin held HIGH. Data can be selected to write only
on the rising edges of WCLK if WSDR is asserted. To guarantee functionality
of the device, WEN must be a controlled signal and not tied to ground. This is
important because WEN must be HIGH during the time when the Master Reset
(MRS) pulse is LOW. In addition, the WSDR pin must be tied HIGH or LOW.
It is not a controlled signal and cannot be changed during FIFO operation.
Write operations can be selected for either Single or Double Data Rate mode.
For Single Data Rate operation, writing into the FIFO requires the Write Single
Data Rate (WSDR) pin to be asserted. Data will be written into the FIFO on the
rising edge of WCLK when the Write Enable (WEN) is asserted. For Double
Data Rate operations, writing into the FIFO requires WSDR to be deasserted.
Data will be written into the FIFO on both rising and falling edge of WCLK when
WEN is asserted.
The output port is controlled by a Read Clock (RCLK) input and a Read
Enable (REN) input. Data is read from the FIFO on every rising and falling edge
of RCLK when REN is asserted and Read Single Data Rate (RSDR) pin held
HIGH. Data can be selected to read only on the rising edges of RCLK if RSDR
is asserted. To guarantee functionality of the device, REN must be a controlled
signal and not tied to ground. This is important because REN must be HIGH
during the time when the Master Reset (MRS) pulse is LOW. In addition, the
RSDR pin must be tied HIGH or LOW. It is not a controlled signal and cannot
be changed during FIFO operation.
Read operations can be selected for either Single or Double Data Rate mode.
Similar to the write operations, reading from the FIFO in single data rate requires
the Read Single Data Rate (RSDR) pin to be asserted. Data will be read from
the FIFO on the rising edge of RCLK when the Read Enable (REN) is asserted.
For Double Data Rate operations, reading into the FIFO requires RSDR to be
deasserted. Data will be read out of the FIFO on both rising and falling edge
of RCLK when and REN is asserted.
Both the input and output port can be selected for either 2.5V LVTTL or HSTL
operation. This can be achieved by tying the HSTL signal LOW for LVTTL or
HIGH for HSTL voltage operation. When the read port is setup for HSTL mode,
the Read Chip Select (RCS) input also has the benefit of disabling the read port
inputs, providing additional power savings.
There is the option of selecting different data rates on the input and output ports
of the device. There are a total of four combinations to choose from, Double Data
Rate to Double Data Rate (DDR to DDR), DDR to Single Data Rate (DDR to
SDR), SDR to DDR, and SDR to SDR. The rates can be set up using the WSDR
and RSDR pins. For example, to set up the input to output combination of DDR
to SDR, WSDR will be HIGH and RSDR will be LOW. Read and write operations
are initiated on the rising edge of RCLK and WCLK respectively, never on the
falling edge. If REN or WEN is asserted after a rising edge of clock, no read or
write operations will be possible on the falling edge of that same pulse.
An Output Enable (OE) input is provided for high-impedance control of the
outputs. A read Chip Select (RCS) input is also provided for synchronous
enable/disable of the read port control input, REN. The RCS input is synchro-
nized to the read clock, and also provides high-impedance controls to the Qn
data outputs. When RCS is disabled, REN will be disabled internally and the
data outputs will be in High-Impedance. Unlike the Read Chip Select signal
however, OE is not synchronous to RCLK. Outputs are high-impedanced
shortly after a delay time when the OE transitions from LOW to HIGH.
The Echo Read Enable (EREN) and Echo Read Clock (ERCLK) outputs
are used to provide tighter synchronization between the data being transmitted
from the Qn outputs and the data being received by the input device. These
output signals from the read port are required for high-speed data communi-
cations. Data read from the read port is available on the output bus with respect
to EREN and ERCLK, which is useful when data is being read at high-speed
operations where synchronization is important.
The frequencies of both the RCLK and WCLK signals may vary from 0 to fMAX
with complete independence. There are no restrictions on the frequency of one
clock input with respect to another.
There are two possible timing modes of operation with these devices: IDT
Standard mode and First Word Fall Through (FWFT) mode.
In IDT Standard mode, the first word written to an empty FIFO will not appear
on the data output lines unless a specific read operation is performed. A read
operation, which consists of activating REN and enabling a rising RCLK edge,
will shift the word from internal memory to the data output lines. Be aware that
in Double Data Rate (DDR) mode only the IDT Standard mode is available.
In FWFT mode, the first word written to an empty FIFO is clocked directly to
the data output lines after three transitions of RCLK. A read operation does not
have to be performed to access the first word written to the FIFO. However,
subsequent words written to the FIFO do require a LOW on REN for access.
The state of the FWFT input during Master Reset determines the timing mode
in use.
For applications requiring more data storage capacity than a single FIFO can
provide, the FWFT timing mode permits depth expansion by chaining FIFOs
in series (i.e. the data outputs of one FIFO are connected to the corresponding
data inputs of the next). No external logic is required.
These FIFOs have four flag pins, EF/OR (Empty Flag or Output Ready), FF/
IR (Full Flag or Input Ready), PAE (Programmable Almost-Empty flag), and
PAF (Programmable Almost-Full flag). The EF and FF functions are selected
in IDT Standard mode. The IR and OR functions are selected in FWFT mode.
PAE and PAF are always available for use, irrespective of timing mode.
4
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
DESCRIPTION (CONTINUED)
PAE and PAF flags can be programmed independently to switch at any point
in memory. Programmable offsets mark the location within the internal memory
that activates the PAE and PAF flags and can only be programmed serially. To
program the offsets, set SEN active and data can be loaded via the Serial Input
(SI) pin at the rising edge of SCLK. To read out the offset registers serially, set
SREN active and data can be read out via the Serial Output (SO) pin at the rising
edge of SCLK. Four default offset settings are also provided, so that PAE can
be marked at a predefined number of locations from the empty boundary and
the PAF threshold can also be marked at similar predefined values from the full
boundary. The default offset values are set during Master Reset by the state
of the FSEL0 and FSEL1 pins.
During Master Reset (MRS), the following events occur: the read and write
pointers are set to the first location of the internal FIFO memory, the FWFT pin
selects IDT Standard mode or FWFT mode, the bus width configuration of the
read and write port is determined by the state of IW and OW, and the default offset
values for the programmable flags are set.
The Partial Reset (PRS) also sets the read and write pointers to the first
location of the memory. However, the timing mode and the values stored in the
programmable offset registers before Partial Reset remain unchanged. The
flags are updated according to the timing mode and offsets in effect. PRS is useful
for resetting a device in mid-operation, when reprogramming programmable
flags would be undesirable.
The timing of the PAE and PAF flags are synchronous to RCLK and WCLK,
respectively . The PAE flag is asserted upon the rising edge of RCLK only and
not WCLK. Similarly the PAF is asserted and updated on the rising edge of
WCLK only and not RCLK.
This device includes a Retransmit from Mark feature that utilizes two control
inputs, MARK and RT (Retransmit). If the MARK input is enabled with respect
to the RCLK, the memory location being read at the point will be marked. Any
subsequent retransmit operation (when RT goes LOW), will reset the read
pointer to this “marked” location.
The device can be configured with different input and output bus widths as
previously stated. These rates are: x40 to x40, x40 to x20,x40 to x10, x20 to
x40, and x10 to x40.
If, at any time, the FIFO is not actively performing an operation, the chip will
automatically power down. Once in the power down state, the standby supply
current consumption is minimized. Initiating any operation (by activating control
inputs) will immediately take the device out of the power down state.
A JTAG test port is provided, here the FIFO has fully functional boundary
Scan feature, compliant with IEEE 1449.1 Standard Test Access Port and
Boundary Scan Architecture.
The Double Data Rate FIFO has the capability of operating in either LVTTL
or HSTL mode. HSTL mode can be selected by enabling the HSTL pin. Both
input and output ports will operate in either HSTL or LVTTL mode, but cannot
be selected independent of one another.
The IDT72T4088/72T4098/72T40108/72T40118 are fabricated using
IDT’s high-speed submicron CMOS technology.
5
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
BM IW OW Write Port Width Read Port Width
L L L x40 x40
H L L x40 x20
H L H x40 x10
H H L x20 x40
H H H x10 x40
TABLE 1 — BUS-MATCHING CONFIGURATION MODES
NOTE:
1. Pin status during Master Reset.
Figure 1. Single Device Configuration Signal Flow Diagram
(x40, x20, x10) DATA OUT (Q
0
- Q
n
)(x40, x20, x10) DATA IN (D
0
- D
n
)
MASTER RESET (MRS)
READ CLOCK (RCLK)
READ ENABLE (REN)
OUTPUT ENABLE (OE)
EMPTY FLAG/OUTPUT READY (EF/OR)
PROGRAMMABLE ALMOST-EMPTY (PAE)
WRITE CLOCK (WCLK)
WRITE ENABLE (WEN)
WRITE SINGLE DATA RATE (WSDR)
FULL FLAG/INPUT READY (FF/IR)
PROGRAMMABLE ALMOST-FULL (PAF)
IDT
72T4088
72T4098
72T40108
72T40118
PARTIAL RESET (PRS)
FIRST WORD FALL THROUGH (FWFT) RETRANSMIT (RT)
5995 drw03
SERIAL ENABLE(SEN)
INPUT WIDTH (IW) OUTPUT WIDTH (OW)
SERIAL CLOCK (SCLK)
MARK
READ CHIP SELECT (RCS)
RCLK ECHO (ERCLK)
REN ECHO (EREN)
WRITE CHIP SELECT (WCS)
READ SINGLE DATA RATE (RSDR)
SERIAL OUTPUT (SO)
SERIAL INPUT (SI)
SERIAL READ ENABLE(SREN)
WSDR RSDR Write Port Width Read Port Width
H H Double Data Rate Double Data Rate
H L Double Data Rate Single Data Rate
L H Single Data Rate Double Data Rate
L L Single Data Rate Single Data Rate
TABLE 2 — DATA RATE-MATCHING CONFIGURATION MODES
NOTE:
1. Pin status during Master Reset.
2. Data Rate Matching can be used in conjunction with Bus-Matching modes.
6
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
PIN DESCRIPTION
BM(1) Bus-Matching LVTTL During Master Reset, this pin along with IW and OW selects the bus sizes for both write and read
(K2) INPUT ports.
D0-D39 Data Inputs HSTL-LVTTL Data inputs for a 40-, 20-, or 10-bit bus. When in 20- or 10- bit mode, the unused input pins are in a don’t
(See Pin No. INPUT care state. The data bus is sampled on both rising and falling edges of WCLK when WEN is enabled and
table for details) DDR Mode is enabled or on the rising edges of WCLK only in SDR Mode.
EF/OR Empty Flag/ HSTL-LVTTL In the IDT Standard mode, the EF function is selected. EF indicates whether or not the FIFO memory
(M14) Output Ready OUTPUT is empty. In FWFT mode, the OR function is selected. OR indicates whether or not there is valid data
available at the outputs.
ERCLK Echo Read HSTL-LVTTL Read Clock Echo output, must be equal to or faster than the Qn data outputs.
(L16) Clock OUTPUT
EREN Echo Read HSTL-LVTTL Read Enable Echo output, used in conjunction with ERCLK.
(K16) Enable OUTPUT
FF/IR Full Flag/ HSTL-LVTTL In the IDT Standard mode, the FF function is selected. FF indicates whether or not the FIFO memory is
(H3) Input Ready OUTPUT empty. In FWFT mode, the IR function is selected. IR indicates whether or not there is space available
for writing to the FIFO memory.
FSEL0(1) Flag Select Bit 0 LVTTL During Master Reset, this input along with FSEL1 will select the default offset values for the programmable
(J3) INPUT flags PAE and PAF. There are four possible settings available.
FSEL1(1) Flag Select Bit 1 L VTTL During Master Reset, this input along with FSEL0 will select the default offset values for the programmable
(J2) INPUT flags PAE and PAF. There are four possible settings available.
FWFT First Word Fall LVTTL During Master reset, selects First Word Fall Through or IDT Standard mode. FWFT is not available in
(G2) Through INPUT DDR mode. In SDR mode, the first word will always fall through on the rising edge.
HSTL(1) HSTL Select LVTTL This input pin is used to select HSTL or 2.5V LVTTL device operation. If HSTL inputs are required, this
(B7) INPUT input must be tied HIGH, otherwise it must be tied LOW and cannot toggle during operation.
IW(1) Input Width LVTTL During Master Reset, this pin along with OW and BM, selects the bus width of the read and write port.
(K1) INPUT
MARK Mark Read HSTL-LVTTL When this pin is asserted the current location of the read pointer will be marked. Any subsequent Retransmit
(E14) Pointer for INPUT operation will reset the read pointer to this position. There is an unlimited number to times to set the mark
Retransmit location, but only the most recent location marked will be acknowledged.
MRS Master Reset HSTL-LVTTL MRS initializes the read and write pointers to zero and sets the output registers to all zeros. During Master
(J1) INPUT Reset, the FIFO is configured for either FWFT or IDT Standard mode, Bus-Matching configurations, and
programmable flag default settings.
OE Output Enable HSTL-LVTTL When HIGH, data outputs Q0-Q39 are in high impedance. When LOW, the data outputs Q0-Q39 are enabled.
(G15) INPUT No other outputs are affected by OE.
OW(1) Output Width LVTTL During Master Reset, this pin along with IW and BM, selects the bus width of the read and write port.
(L3) INPUT
PAE Programmable HSTL-LVTTL PAE goes HIGH if the number of words in the FIFO memory is greater than or equal to offset n, which is
(L15) Almost-Empty OUTPUT stored in the Empty Offset register. PAE goes LOW if the number of words in the FIFO memory is less than
Flag offset n.
PAF Programmable HSTL-LVTTL PAF goes HIGH if the number of free locations in the FIFO memory is more than offset m, which is stored
(G3) Almost-Full Flag OUTPUT in the Full Offset register. PAF goes LOW if the number of free locations in the FIFO memory is less than
or equal to m.
PRS Partial Reset HSTL-LVTTL PRS initializes the read and write pointers to zero and sets the output registers to all zeros. During Partial
(K3) INPUT Reset, the existing mode (IDT standard or FWFT) and programmable flag settings are not affected.
Q0-Q39 Data Outputs HSTL-LVTTL Data outputs for a 40-, 20-, or 10-bit bus. When in 20- or 10- bit mode, the unused output pins should not
(See Pin No. OUTPUT be connected. The output data is clocked on both rising and falling edges of RCLK when REN is enabled
table for details) and DDR Mode is enabled or on the rising edges of RCLK only in SDR Mode.
RCLK Read Clock HSTL-LVTTL Input clock when used in conjunction with REN for reading data from the FIFO memory and output register.
(G16) INPUT
Symbol & Name I/O TYPE Description
Pin No.
7
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
PIN DESCRIPTION (CONTINUED)
RCS Read Chip Select HSTL-LVTTL RCS provides synchronous enable/disable control of the read port and High-Impedance control of the
(F14) INPUT Qn data outputs, synchronous to RCLK. When using RCS the OE pin must be tied LOW. During Master
or Partial Reset the RCS input is don’t care, if OE is LOW the data outputs will be Low-Impedance
regardless of RCS.
REN Read Enable HSTL-LVTTL When LOW and in DDR mode, REN along with a rising and falling edge of RCLK will send data in FIFO
(F16) INPUT memory to the output register and read the current data in output register. In SDR mode data will only be
read on the rising edge of RCLK only.
RSDR(1) Read Single Data LVTTL When LOW, this input pin sets the read port to Single Data Clock mode. When HIGH, the read port will operate
(L2) Rate INPUT in Double Data Clock mode. This pin must be tied either HIGH or LOW and cannot toggle during operation.
RT Retransmit HSTL-LVTTL RT asserted on the rising edge of RCLK initializes the read pointer to the first location in memory. EF flag
(F15) INPUT is set to LOW (OR to HIGH in FWFT mode). The write pointer, offset registers, and flag settings are not
affected. If a mark has been set via the MARK input pin, then the read pointer will initialize to the mark location
when RT is asserted.
SCLK Serial Clock LVTTL A rising edge of SCLK will clock the serial data present on the SI input into the offset registers provided
(H15) INPUT that SEN is enabled. A rising edge of SCLK will also read data out of the offset registers provided that SREN
is enabled.
SEN Serial Input HSTL-LVTTL SEN used in conjunction with SI and SCLK enables serial loading of the programmable flag offsets.
(J15) Enable INPUT
SREN Serial Read HSTL-LVTTL SREN used in conjunction with SO and SCLK enables serial reading of the programmable flag offsets.
(J16) Enable INPUT
SI Serial Input HSTL-LVTTL This input pin is used to load serial data into the programmable flag offsets. Used in conjunction with SEN
(H16) INPUT and SCLK.
SO Serial Output HSTL-LVTTL This output pin is used to read data from the programmable flag offsets. Used in conjunction with SREN
(K15) OUTPUT and SCLK.
TCK(2) JTAG Clock HSTL-LVTTL Clock input for JTAG function. One of four terminals required by IEEE Standard 1149.1-1990. Test
(F1) INPUT operations of the device are synchronous to TCK. Data from TMS and TDI are sampled on the rising edge
of TCK and outputs change on the falling edge of TCK. If the JTAG function is not used this signal needs
to be tied to GND.
TDI(2) JTAG Test Data HSTL-LVTTL One of four terminals required by IEEE Standard 1149.1-1990. During the JTAG boundary scan operation,
(E2) Input INPUT test data serially loaded via the TDI on the rising edge of TCK to either the Instruction Register, ID Register
and Bypass Register. An internal pull-up resistor forces TDI HIGH if left unconnected.
TDO(2) JTAG Test Data HSTL-LVTTL One of four terminals required by IEEE Standard 1149.1-1990. During the JTAG boundary scan operation,
(F3) Output OUTPUT test data serially loaded output via the TDO on the falling edge of TCK from either the Instruction Register,
ID Register and Bypass Register. This output is high impedance except when shifting, while in SHIFT-
DR and SHIFT-IR controller states.
TMS(2) JTAG Mode HSTL-LVTTL TMS is a serial input pin. One of four terminals required by IEEE Standard 1149.1-1990. TMS directs the
(F2) Select INPUT the device through its TAP controller states. An internal pull-up resistor forces TMS HIGH if left unconnected.
TRST(2) JTAG Reset HSTL-LVTTL TRST is an asynchronous reset pin for the JTAG controller. The JTAG TAP controller does not
(E3) INPUT automatically reset upon power-up, thus it must be reset by either this signal or by setting TMS= HIGH for
five TCK cycles. If the TAP controller is not properly reset then the FIFO outputs will always be in high-
impedance. If the JTAG function is used but the user does not want to use TRST, then TRST can be tied
with MRS to ensure proper FIFO operation. If the JTAG function is not used then this signal needs to be
tied to GND. An internal pull-up resistor forces TRST HIGH if left unconnected.
WCLK Write Clock HSTL-LVTTL Input clock when used in conjunction with WEN for writing data into the FIFO memory.
(G1) INPUT
WCS Write Chip Select HSTL-LVTTL The WCS pin can be regarded as a second WEN input, enabling/disabling write operations.
(H2) INPUT
WEN Write Enable HSTL-LVTTL When LOW and in DDR mode, WEN along with a rising and falling edge of WCLK will write data into the
(H1) INPUT FIFO memory. In SDR mode data will only be read on the rising edge of RCLK only.
Symbol & Name I/O TYPE Description
Pin No.
8
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
PIN DESCRIPTION (CONTINUED)
Symbol & Name I/O TYPE Description
Pin No.
WSDR(1) Write Single Data LVTTL When LOW, this input pin sets the write port to Single Data Clock mode. When HIGH, the write port will
(L1) Rate INPUT operate in Double Data Clock mode. This pin must be tied either HIGH or LOW and cannot toggle
during operation.
VCC +2.5V Supply INPUT There are Vcc supply inputs and must be connected to the 2.5V supply rail.
(See below)
VDDQ O/P Rail Voltage INPUT This pin should be tied to the desired voltage rail for providing power to the output drivers. Nominally 1.5V
(See below) or 1.8V for HSTL, 2.5V for LVTTL.
GND Core Ground Pin INPUT These are Ground pins are for the core device and must be connected to the GND rail.
(See below)
Vref Reference INPUT This is a Voltage Reference input and must be connected to a voltage level determined in the
(T3) Voltage Recommended DC Operating Conditions section. This provides the reference voltage when using HSTL
class inputs. If HSTL class inputs are not being used, this pin must be connected to GND.
PIN NUMBER TABLE
Symbol Name I/O TYPE Pin Number
D0-39 Data Inputs HSTL-LVTTL D0-C3, D1-A4, D2-B4, D3-C4, D4-A5, D5-B5, D6-C5, D7-A6, D8-B6, D9-A7, D10-R7, D11-T7,
INPUT D12-R6, D13-T6, D14-R5, D15-T5, D16-R4, D17-T4, D18-P3, D19-R3, D20-N2, D21-P2, D22-R2,
D23-N1, D24-P1, D25-R1, D26-N3, D(27-29)-M(1-3), D30-E1, D(31-33)-D(3-1), D34-C1,
D(35,36)-B(1,2), D37-C2, D38-A3, D39-B3
Q0-39 Data Outputs HSTL-LVTTL Q0-B10, Q1-A10, Q2-B11, Q3-A11, Q4-B12, Q5-A12, Q6-B13, Q7-A13, Q8-B14, Q9-A14, Q10-T14
OUTPUT Q11-R14, Q12-T13, Q13-R13, Q14-T12, Q15-R12, Q16-T11, Q17-R11, Q18-T10, Q19-R10,
Q(20,21)-C(14,15), Q(22,23)-B(15,16), Q24-C16, Q(25-27)-D(16-14), Q(28,29)-E(16,15),
Q(30,31)-M(15,16), Q(32-34)- N(14-16), Q(35-37)-P(14-16), Q(38,39)-R(15,16)
VCC +2.5V Supply INPUT A(1,2), C(6,7), D(4-7), K4, L4, M4, N(4-7), P(5-7), T(1,2)
VDDQ O/P Rail Voltage INPUT A(15,16), C(10-13), D(10-13), E13, F(4,13), G(4,14), H(4,14), J14, K14, L14, M13, N(10-13),
P(10-13), T(15,16)
GND Ground Pin INPUT A(8,9), B(8,9), C(8,9), D(8,9), E4, G(7-10,13), H(7-10,13), J(4,7-10,13), K(7-10,13), L13, N(8,9),
P(4,8,9), R(8,9), T(8,9)
NOTES:
1. Inputs should not change state after Master Reset.
2. These pins are for the JTAG port. Please refer to pages 25-28 and Figures 5-7.
9
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Symbol Rating Commercial Unit
VTERM Terminal Voltage –0.5 to +3.6(2) V
with respect to GND
TSTG Storage Temperature –55 to +125 °C
IOUT DC Output Current –50 to +50 mA
DC ELECTRICAL CHARACTERISTICS
(Commercial: VCC = 2.5V ± 0.125V, TA = 0°C to +70°C;Industrial: VCC = 2.5V ± 0.125V, T A = -40°C to +85°C)
Symbol Parameter Min. Max. Unit
ILI Input Leakage Current –10 10 µA
ILO Output Leakage Current –10 10 µA
VOH(5) Output Logic “1” Voltage, IOH = –8 mA @VDDQ = 2.5V ± 0.125V (LVTTL) VDDQ -0.4 — V
IOH = –8 mA @VDDQ = 1.8V ± 0.1V (eHSTL) VDDQ -0.4 — V
IOH = –8 mA @VDDQ = 1.5V ± 0.1V (HSTL) VDDQ -0.4 — V
VOL Output Logic “0” Voltage, IOL = 8 mA @VDDQ = 2.5V ± 0.125V (LVTTL) — 0.4V V
IOL = 8 mA @VDDQ = 1.8V ± 0.1V (eHSTL) — 0.4V V
IOL = 8 mA @VDDQ = 1.5V ± 0.1V (HSTL) — 0.4V V
ICC1(1,2) Active VCC Current (VCC = 2.5V) I/O = LVTTL — 20 mA
I/O = HSTL — 60 mA
I/O = eHSTL — 60 mA
ICC2(1) Standby VCC Current (VCC = 2.5V) I/O = LVTTL — 1 0 mA
I/O = HSTL — 50 mA
I/O = eHSTL — 50 mA
ABSOLUTE MAXIMUM RATINGS
RECOMMENDED DC OPERATING CONDITIONS
NOTES:
1. Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause
permanent damage to the device. This is a stress rating only and functional operation
of the device at these or any other conditions above those indicated in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect reliability.
2. Compliant with JEDEC JESD8-5. VCC terminal only.
Symbol Parameter(1) Conditions Max. Unit
CIN(2,3) Input VIN = 0V 10(3) pF
Capacitance
COUT(1,2) Output VOUT = 0V 10 pF
Capacitance
CAPACITANCE (TA = +25°C, f = 1.0MHz)
NOTES:
1. With output deselected, (OE ≥ VIH).
2. Characterized values, not currently tested.
3. CIN for Vref is 20pF.
NOTES:
1 . Both WCLK and RCLK toggling at 20MHz. Data inputs toggling at 10MHz. WCS = HIGH, REN or RCS = HIGH.
2. Typical ICC1 calculation:for LVTTL I/O ICC1 (mA) = 0.6mA x fs, fs = WCLK frequency = RCLK frequency (in MHz)
for HSTL or eHSTL I/O ICC1 (mA) = 38mA + (0.7mA x fs), fs = WCLK frequency = RCLK frequency (in MHz)
3. Typical IDDQ calculation: With Data Outputs in High-Impedance: IDDQ (mA) = 0.15mA x fs
With Data Outputs in Low-Impedance: IDDQ (mA) = (CL x VDDQ x fs x 2N)/2000
fs = WCLK frequency = RCLK frequency (in MHz), VDDQ = 2.5V for LVTTL; 1.5V for HSTL; 1.8V for eHSTL, N = Number of outputs switching.
tA = 25°C, CL = capacitive load (pf)
4. Total Power consumed: PT = [(VCC x ICC) + (VDDQ x IDDQ)].
5. Outputs are not 3.3V tolerant.
NOTE:
1. VREF is only required for HSTL or eHSTL inputs. VREF should be tied LOW for LVTTL operation.
Symbol Parameter Min. Typ. Max. Unit
VCC Supply Voltage 2.375 2.5 2.625 V
VDDQ Output Rail Voltage for I/Os 2.375 2.5 2.625 V
GND Supply Voltage 0 0 0 V
VIH Input High Voltage ⎯ LVTTL 1.7 — 3.45 V
⎯ eHSTL VREF+0.2 — — V
⎯ HSTL VREF+0.2 — — V
VIL Input Low Voltage ⎯ LVTTL -0.3 — 0.7 V
⎯ eHSTL — — VREF-0.2 V
⎯ HSTL — — VREF-0.2 V
VREF Voltage Reference Input ⎯ eHSTL 0 .8 0 .9 1.0 V
(HSTL only) ⎯ HSTL 0.68 0.75 0.9 V
TAOperating Temperature Commercial 0 — 70 °C
TAOperating Temperature Industrial -40 — 85 °C
10
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
AC ELECTRICAL CHARACTERISTICS(1)
(Commercial: VCC = 2.5V ± 5%, TA = 0°C to +70°C;Industrial: VCC = 2.5V ± 5%, TA = -40 °C to +85°C)
Commercial Commercial Com’l & Ind’l(2) Commercial
IDT72T4088L4 IDT72T4088L5 IDT72T4088L6-7 IDT72T4088L10
IDT72T4098L4 IDT72T4098L5 IDT72T4098L6-7 IDT72T4098L10
IDT72T40108L4 IDT72T40108L5 IDT72T40108L6-7 IDT72T40108L10
IDT72T40118L4 IDT72T40118L5 IDT72T40118L6-7 IDT72T40118L10
Symbol Parameter Min. Max. Min. Max. Min. Max. Min. Max. Unit
fS1 Clock Cycle Frequency SDR — 250 — 200 — 150 — 100 MH z
fS2 Clock Cycle Frequency DDR — 110 — 100 — 75 — 50 MHz
tAData Access Time 0.6 3.2 0.6 3.6 0.6 3.8 0.6 4.5 ns
tASO Data Access Serial Output Time 0.6 3.2 0.6 3.6 0.6 3.8 0.6 4.5 ns
tCLK1 Clock Cycle Time SDR 4 — 5 — 6.7 — 10 — ns
tCLK2 Clock Cycle Time DDR 9.1 — 10 — 13 — 20 — ns
tCLKH1 Clock High Time SDR 1 . 8 — 2 .3 — 2. 8 — 4.5 — n s
tCLKH2 Clock High Time DDR 4 .0 — 4 . 5 — 6 .0 — 9 . 5 — n s
tCLKL1 Clock Low Time SDR 1 .8 — 2. 3 — 2.8 — 4.5 — n s
tCLKL2 Clock Low Time DDR 4 . 0 — 4. 5 — 6 . 0 — 9 . 5 — ns
tDS Data Setup Time 1.2 — 1.5 — 2.0 — 3.0 — ns
tDH Data Hold Time 0.5 — 0.5 — 0.5 — 0.5 — ns
tENS Enable Setup Time 1.2 — 1.5 — 2.0 — 3.0 — ns
tENH Enable Hold Time 0.5 — 0.5 — 0.5 — 0.5 — ns
tWCSS WCS setup time 1.2 — 1.5 — 2.0 — 3.0 — ns
tWCSH WCS hold time 0.5 — 0.5 — 0.5 — 0.5 — ns
fCClock Cycle Frequency (SCLK) — 10 — 10 — 10 — 10 M Hz
tSCLK Serial Clock Cycle 100 — 100 — 100 — 100 — ns
tSCKH Serial Clock High 45 — 45 — 45 — 45 — ns
tSCKL Serial Clock Low 45 — 45 — 45 — 45 — ns
tSDS Serial Data In Setup 15 — 15 — 15 — 15 — ns
tSDH Serial Data In Hold 5 — 5 — 5 — 5 — ns
tSENS Serial Enable Setup 5 — 5 — 5 — 5 — ns
tSENH Serial Enable Hold 5 — 5 — 5 — 5 — ns
tRS Reset Pulse Width(3) 30 — 30 — 30 — 30 — ns
tRSS Reset Setup Time 15 — 15 — 15 — 15 — ns
tHRSS HSTL Reset Setup Time 4 — 4 — 4 — 4 — µs
tRSR Reset Recovery Time 10 — 10 — 10 — 10 — ns
tRSF Reset to Flag and Output Time — 10 — 12 — 15 — 15 ns
tOLZ Output Enable to Output in Low Z(4) 0—0—0—0—ns
tOE Output Enable to Output Valid — 3.2 — 3.6 — 3.8 — 4.5 ns
tOHZ Output Enable to Output in High Z(4) — 3.2 — 3.6 — 3.8 — 4.5 ns
tWFF Write Clock to FF or IR — 3.2 — 3.6 — 3.8 — 4.5 ns
tREF Read Clock to EF or OR — 3.2 — 3.6 — 3.8 — 4.5 ns
tPAFS Write Clock to Programmable Almost-Full Flag — 3.2 — 3.6 — 3.8 — 4.5 ns
tPAES Read Clock to Programmable Almost-Empty Flag — 3.2 — 3.6 — 3.8 — 4.5 ns
tERCLK RCLK to Echo RCLK output — 3 .6 — 4 — 4 .3 — 5 ns
tCLKEN RCLK to Echo REN output — 3. 2 — 3. 6 — 3. 8 — 4 .5 n s
tRCSLZ RCLK to Active from High-Z — 3. 2 — 3. 6 — 3 .8 — 4 .5 n s
tRCSHZ RCLK to High-Z(4) — 3.2 — 3.6 — 3.8 — 4.5 ns
tSKEW1 Skew time between RCLK and WCLK for EF/OR and FF/IR 3.5—4—5—7—ns
tSKEW2 Skew time between RCLK & WCLK for EF/OR & FF/IR in DDR mode 3.5—4—5—7—ns
tSKEW3 Skew time between RCLK and WCLK for PAE and PAF 4—5—6—8—ns
NOTES:
1. All AC timings apply to both IDT Standard mode and First Word Fall Through mode.
2. Industrial temperature range product for the 6-7ns speed grade is available as a standard device. All other speed grades are available by special order.
3. Pulse widths less than minimum values are not allowed.
4. Values guaranteed by design, not currently tested.
11
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Input Pulse Levels 0.25 to 1.25V
Input Rise/Fall Times 0.4ns
Input Timing Reference Levels 0.75V
Output Reference Levels 0.75V
HSTL
1.5V AC TEST CONDITIONS
Figure 2b. Lumped Capacitive Load, Typical Derating
AC TEST LOADS
Figure 2a. AC Test Load
Input Pulse Levels 0.4 to 1.4V
Input Rise/Fall Times 0.4ns
Input Timing Reference Levels 0.9V
Output Reference Levels 0.9V
EXTENDED HSTL
1.8V AC TEST CONDITIONS
Input Pulse Levels GND to 2.5V
Input Rise/Fall Times 1ns
Input Timing Reference Levels 1.25V
Output Reference Levels 1.25V
2.5V LVTTL
2.5V AC TEST CONDITIONS
NOTE:
1. VDDQ = 1.5V±.
NOTE:
1. VDDQ = 1.8V±.
NOTE:
1. For LVTTL VCC = VDDQ.
5995 drw04
50
Ω
VDDQ/2
I/O Z
0
= 50
Ω
10pF
5995 drw04a
6
5
4
3
2
1
20 30 50 80 100 200
Ca
p
acitance
(p
F
)
tCD
(Typical, ns)
12
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
OUTPUT ENABLE & DISABLE TIMING
V
IH
OE
V
IL
t
OE &
t
OLZ
V
CC
2
V
CC
2
100mV
100mV
t
OHZ
100mV
100mV
Output
Normally
LOW
Output
Normally
HIGH
V
OL
V
OH
V
CC
2
V
CC
2
5995 drw04b
Output
Enable
Output
Disable
READ CHIP SELECT ENABLE & DISABLE TIMING
V
IH
RCS
V
IL
t
ENS
t
ENH
t
RCSLZ
RCLK
V
CC
2
V
CC
2
100mV
100mV
t
RCSHZ
100mV
100mV
Output
Normally
LOW
Output
Normally
HIGH
V
OL
V
OH
V
CC
2
V
CC
2
5995 drw04c
NOTES:
1. REN is HIGH.
2. RCS is LOW.
NOTES:
1. REN is HIGH.
2. OE is LOW.
13
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
FUNCTIONAL DESCRIPTION
TIMING MODES: IDT STANDARD vs FIRST WORD FALL THROUGH
(FWFT) MODE
The IDT72T4088/72T4098/72T40108/72T40118 support two different
timing modes of operation: IDT Standard mode or First Word Fall Through
(FWFT) mode. The selection of which mode will operate is determined during
Master Reset, by the state of the FWFT input.
During Master Reset, if the FWFT pin is LOW, then IDT Standard mode will
be selected. This mode uses the Empty Flag (EF) to indicate whether or not there
are any words present in the FIFO. It also uses the Full Flag function (FF) to
indicate whether or not the FIFO has any free space for writing. In IDT Standard
mode, every word read from the FIFO, including the first, must be requested
using the Read Enable (REN) and RCLK.
If the FWFT pin is HIGH during Master Reset, then FWFT mode will be
selected. This mode uses Output Ready (OR) to indicate whether or not there
is valid data at the data outputs (Qn). It also uses Input Ready (IR) to indicate
whether or not the FIFO has any free space for writing. In the FWFT mode, the
first word written to an empty FIFO goes directly to Qn after three RCLK rising
edges, applying REN = LOW is not necessary. However, subsequent words
must be accessed using the Read Enable (REN) and RCLK.
Various signals, in both inputs and outputs operate differently depending on
which timing mode is in effect.
IDT ST ANDARD MODE
In this mode, the status flags FF, PAF, PAE, and EF operate in the manner
outlined in Table 4. To write data into the FIFO, Write Enable (WEN) must be
LOW. Data presented to the DATA IN lines will be clocked into the FIFO on
subsequent transitions of the Write Clock (WCLK). After the first write is
performed, the Empty Flag (EF) will go HIGH. Subsequent writes will continue
to fill up the FIFO. The Programmable Almost-Empty flag (PAE) will go HIGH
after n + 1 words have been loaded into the FIFO, where n is the empty offset
value. The default setting for these values are listed in Table 3. This parameter
is also user programmable. See section on Programmable Flag Offset Loading.
Continuing to write data into the FIFO without performing read operations will
cause the Programmable Almost-Full flag (PAF) to go LOW. Again, if no reads
are performed, the PAF will go LOW after (16,384-m) writes for the IDT72T4088,
(32,768-m) writes for the IDT72T4098, (65,536-m) writes for the IDT72T40108
and (131,072-m) writes for the IDT72T40118. The offset “m” is the full offset
value. The default setting for these values are listed in Table 3. This parameter
is also user programmable. See the section on Programmable Flag Offset
Loading.
When the FIFO is full, the Full Flag (FF) will go LOW, inhibiting further write
operations. If no reads are performed after a reset, FF will go LOW after D writes
to the FIFO. D = 16,384 writes for the IDT72T4088, 32,768 writes for the
IDT72T4098, 65,536 writes for the IDT72T40108 and 131,072 writes for the
IDT72T40118, respectively.
If the FIFO is full, the first read operation will cause FF to go HIGH. Subsequent
read operations will cause PAF to go HIGH at the conditions described in Table
4 If further read operations occur, without write operations, PAE will go LOW
when there are n words in the FIFO, where n is the empty offset value.
Continuing read operations will cause the FIFO to become empty. Then the last
word has been read from the FIFO, the EF will go LOW inhibiting further read
operations. REN is ignored when the FIFO is empty.
When configured in IDT Standard mode, the EF and FF outputs are double
register-buffered outputs. IDT Standard mode is available when the device is
configured in both Single Data Rate and Double Data Rate mode.
Relevant timing diagrams for IDT Standard mode can be found in Figure 10,
11, 12, 13, 14, 15, 16, 17, 18 and 23.
FIRST WORD FALL THROUGH MODE (FWFT)
In this mode, the status flags OR, IR, PAE, and PAF operate in the manner
outlined in Table 5. To write data into to the FIFO, WEN must be LOW. Data
presented to the DATA IN lines will be clocked into the FIFO on subsequent
transitions of WCLK. After the first write is performed, the Output Ready (OR)
flag will go LOW. Subsequent writes will continue to fill up the FIFO. PAE will go
HIGH after n + 2 words have been loaded into the FIFO, where n is the empty
offset value. The default setting for these values are listed in Table 3. This
parameter is also user programmable. See section on Programmable Flag
Offset Loading.
Continuing to write data into the FIFO without performing read operations will
cause the Programmable Almost-Full flag (PAF) to go LOW. Again, if no reads
are performed, the PAF will go LOW after (16,385-m) writes for the IDT72T4088,
(32,769-m) writes for the IDT72T4098, (65,537-m) writes for the IDT72T40108
and (131,073-m) writes for the IDT72T40118. The offset “m” is the full offset
value. The default setting for these values are listed in Table 3. This parameter is
also user programmable. See the section on Programmable Flag Offset Loading.
When the FIFO is full, the Input Ready (IR) will go LOW, inhibiting further write
operations. If no reads are performed after a reset, IR will go LOW after D writes
to the FIFO. D = 16,385 writes for the IDT72T4088, 32,769 writes for the
IDT72T4098, 65,537 writes for the IDT72T40108 and 131,073 writes for the
IDT72T40118, respectively. Note that the additional word in FWFT mode is due
to the capacity of the memory plus output register.
If the FIFO is full, the first read operation will cause IR to go HIGH. Subsequent
read operations will cause PAF to go HIGH at the conditions described in Table
5. If further read operations occur, without write operations, PAE will go LOW
when there are n words in the FIFO, where n is the empty offset value.
Continuing read operations will cause the FIFO to become empty. Then the last
word has been read from the FIFO, the OR will go HIGH inhibiting further read
operations. REN is ignored when the FIFO is empty.
When configured in FWFT mode, the OR flag output is triple register-buffered
and the IR flag output is double register-buffered. FWFT mode is only available
when the device is configured in Single Data Rate mode.
Relevant timing diagrams for IDT Standard mode can be found in Figure 19,
20, 21, 22 and 24.
14
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
IDT72T4088, 72T4098, 72T40108, 72T401 18
FSEL1 FSEL0 Offsets n,m
H H 255
L H 127
HL63
LL7
TABLE 3 — DEFAULT PROGRAMMABLE
FLAG OFFSETS
NOTES:
1. n = empty offset for PAE.
2 . m = full offset for PAF.
PROGRAMMING FLAG OFFSETS
Full and Empty Flag offset values are user programmable. The IDT72T4088/
72T4098/72T40108/72T40118 have internal registers for these offsets. There
are four selectable default offset values during Master Reset. These offset values
are shown in Table 3. The offset values can also be programmed serially into
the FIFO. To load offset values, set SEN LOW and the rising edge of SCLK will
IDT72T4088 IDT72T4098
00
1 to n (1)
(16,384-m) to 16,383
16,384
IDT72T40118
0
TABLE 4 ⎯ STATUS FLAGS FOR IDT STANDARD MODE
TABLE 5 ⎯ STATUS FLAGS FOR FWFT MODE
FF PAF PAE EF
HHLL
HHLH
HHHH
HL HH
LLHH
Number of
Words in
FIFO
5995 drw05
IDT72T40108
0
(8,193) to (16,384-(m+1))
(32,768-m) to 32,767
32,768
(16,385) to (32,768-(m+1))
(65,536-m) to 65,535
65,536
(32,769) to (65,536-(m+1))
(131,072-m) to 131,071
131,072
(65,537) to (131,072-(m+1))
IDT72T4088 IDT72T4098
00
1 to n+1 (1)
(16,385-m) to 16,384
16,385
IDT72T40118
0
IR PAF PAE OR
LHLH
LHLL
L HHL
LLHL
HLHL
Number of
Words in
FIFO
IDT72T40108
0
(8,194) to (16,385-(m+1))
(32,769-m) to 32,768
32,769
(16,386) to (32,769-(m+1))
(65,537-m) to 65,536
65,537
(32,770) to (65,537-(m+1))
(131,073-m) to 131,072
131,073
(65,538) to (131,073-(m+1))
1 to n (1) 1 to n (1) 1 to n (1)
1 to n+1 (1) 1 to n+1 (1) 1 to n+1 (1)
NOTE:
1. See table 3 for values for n, m.
NOTE:
1. See table 3 for values for n, m.
2. FWFT mode available only in Single Data Rate mode.
load data from the SI input into the offset registers. SCLK runs at a nominal speed
of 10MHz at the maximum. The programming sequence starts with one bit for
each SCLK rising edge, starting with the Empty Offset LSB and ending with the
Full Offset MSB. The total number of bits per device is listed in Figure 3,
Programmable Flag Offset Programming Sequence. See Figure 25, Loading
of Programmable Flag Registers, for the timing diagram for this mode. The PAE
and PAF can show a valid status only after the complete set of bits (for all offset
registers) has been entered. The registers can be reprogrammed as long as
the complete set of new offset bits is entered.
In addition to loading offset values into the FIFO, it is also possible to read
the current offset values. Similar to loading offset values, set SREN LOW and
the rising edge of SCLK will send data from the offset registers out to the SO output
port. When initializing a read to the offset registers, data will be read starting from
the first location in the register, regardless of where it was last read.
Figure 3, Programmable Flag Offset Programming Sequence, summarizes
the control pins and sequence for programming offset registers and reading and
writing into the FIFO.
The offset registers may be programmed (and reprogrammed) any time
after Master Reset. V alid programming ranges are from 0 to D-1.
15
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 3. Programmable Flag Offset Programming Sequence
NOTES:
1. The programming sequence applies to both IDT Standard and FWFT modes.
2. When the input or output ports are in DDR mode, the depth is reduced by half but the overall density remains the same. For example, the IDT72T4088 in SDR mode is
16,384 x 40 = 655,360, in DDR mode the configuration becomes 8,192 x 80 = 655,360. In both cases, the total density are the same.
WCLK RCLK
X
WSDR
X
X
RSDR
X
X
SEN
0
1X
SREN
1
0
IDT72T4088
IDT72T4098
IDT72T40108
IDT72T40118
SCLK
X
5995 drw06
X
WEN
1
1
REN
1
1
In SDR Mode
X11 XX Write Memory (DDR)
X01
X01 XX Write Memory (SDR)
X01
X11 XX Read Memory (DDR)
X10
X10 XX Read Memory (SDR)
X10
XXX No Operation
X11 XXX
1 bit for each rising SCLK edge
Starting with Empty Offset
(LSB) Ending with Full Offset
(MSB)
Serial write to registers:
28 bits for the IDT72T4088
30 bits for the IDT72T4098
32 bits for the IDT72T40108
34 bits for the IDT72T40118
Serial write to registers:
In DDR Mode
26 bits for the IDT72T4088
28 bits for the IDT72T4098
30 bits for the IDT72T40108
32 bits for the IDT 72T40118
1 bit for each rising SCLK edge
Starting with Empty Offset
(LSB) Ending with Full Offset
(MSB)
In SDR Mode
1 bit for each rising SCLK edge
Starting with Empty Offset
(LSB) Ending with Full Offset
(MSB)
Serial read from registers:
28 bits for the IDT72T4088
30 bits for the IDT72T4098
32 bits for the IDT72T40108
34 bits for the IDT72T40118
In DDR Mode
1 bit for each rising SCLK edge
Starting with Empty Offset
(LSB) Ending with Full Offset
(MSB)
Serial read from registers:
26 bits for the IDT72T4088
28 bits for the IDT72T4098
30 bits for the IDT72T40108
32 bits for the IDT72T40118
16
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
RETRANSMIT FROM MARK OPERA TION
The Retransmit from Mark feature allows FIFO data to be read repeatedly
starting at a user-selected position. The FIFO is first put into retransmit mode
that will “mark” a beginning word and also set a pointer that will prevent
ongoing FIFO write operations from over-writing retransmit data. The retrans-
mit data can be read repeatedly any number of times from the “marked”
position. The FIFO can be taken out of retransmit mode at any time to allow
normal device operation. The “mark” position can be selected any number of
times, each selection over-writing the previous mark location.
In Double Data Rate, data is always marked in pairs. That is, the unit of data
read on the rising and falling edge of WCLK. If the data marked was read on
the falling edge of RCLK, then the marked data will be the unit of data read from
the rising and falling edge of that particular RCLK edge. Refer to Figure 23,
Retransmit from Mark in Double Data Rate Mode, for the timing diagram in
this mode. Retransmit operation is available in both IDT standard and FWFT
modes.
During IDT standard mode the FIFO is put into retransmit mode by a Low-
to-High transition on RCLK when the MARK input is HIGH and EF is HIGH.
The rising RCLK edge marks the data present in the FIFO output register as
the first retransmit data. Again, the data is marked in pairs. Thus if the data
marked was read on the falling edge of RCLK, the first part of retransmit will
read out the data read on the rising edge of RCLK, followed by the data on the
falling edge (the marked data). The FIFO remains in retransmit mode until a
rising edge on RCLK occurs while MARK is LOW .
Once a marked location has been set, a retransmit can be initiated by a
rising edge on RCLK while the Retransmit input (RT) is LOW . REN must be
HIGH (reads disabled) before bringing RT LOW. The device indicates the start
of retransmit setup by setting EF LOW, also preventing reads. When EF goes
HIGH, retransmit setup is complete and read operations may begin starting
with the first unit of data at the MARK location. Since IDT standard mode is
selected, every word read including the first “marked” word following a re-
transmit setup requires a LOW on REN.
Note, write operations may continue as normal during all retransmit functions,
however write operations to the “marked” location will be prevented. See Figure
23, Retransmit from Mark in Double Data Rate Mode, for the relevant timing
diagram.
During FWFT mode the FIFO is put into retransmit mode by a rising RCLK
edge when the MARK input is HIGH and OR is LOW. The rising RCLK edge
marks the data present in the FIFO output register as the first retransmit data.
The data is marked in pairs. The FIFO remains in retransmit mode until a
rising RCLK edge occurs while MARK is LOW .
Once a marked location has been set, a retransmit can be initiated by a
rising RCLK edge while the Retransmit input (RT) is LOW. REN must be
HIGH (reads disabled) before bringing RT LOW . The device indicates the
start of retransmit setup by setting OR HIGH, preventing read operations.
When OR goes LOW , retransmit setup is complete and on the next rising
RCLK edge (RT goes HIGH), the contents of the first retransmit location are
loaded onto the output register . Since FWFT mode is selected, the first word
appears on the outputs regardless of REN, a LOW on REN is not required for
the first word. Reading all subsequent words requires a LOW on REN to
enable the rising RCLK edge. See Figure 24, Retransmit from Mark (FWFT
mode) for the relevant timing diagram.
Before a retransmit can be performed, there must be at least 1280 bits
(or 160 bytes) of data between the write pointer and mark location.
That is, 40 bits x32 for the x40 mode, 20 bits x64 for the x20 mode, and 10 bits
x128 for the x10 mode. Also, once the Mark is set, the write pointer will not
increment past the marked location, preventing overwrites of retransmit data.
HSTL/LVTTL I/O
This device supports both LVTTL and HSTL logic levels on the input and
output signals. If LVTTL is desired, a LOW on the HSTL pin will set the inputs
and outputs to LVTTL mode. If HSTL is desired, a HIGH on the HSTL pin will
set the inputs and outputs to HSTL mode. VREF is the input voltage reference
used in HSTL mode. Typically a logic HIGH in HSTL would be Vref + 0.2V and
a logic LOW would be VREF – 0.2V. Table 6 illustrates which pins are and are
not associated with this feature. Note that all “Static Pins” must be tied to Vcc or
GND. These pins are LVTTL only and are purely device configuration pins.
HSTL SELECT STATIC PINS
HIGH = HSTL L VTTL ONL Y
LOW = L VTTL
Write Port Read Port Signal Pins Static Pins
Dn (I/P) Qn (O/P) EF/OR (O/P) SCLK (I/P) TRST (I/P) IW (I/P)
WCLK (I/P) RCLK (I/P) PAF (O/P) SI (I/P) TDI (I/P) OW (I/P)
WEN (I/P) REN (I/P) PAE (O/P) SO (O/P) TDO (O/P) BM ((I/P)
WCS (I/P) RCS (I/P) FF/IR (O/P) MRS (I/P) SEN (I/P) HSTL (I/P)
MARK (I/P) ERCLK (O/P) PRS (I/P) SREN (I/P) FSEL1 (I/P)
OE (I/P) EREN (O/P) TCK (I/P) FSEL0 (I/P)
RT (I/P) TMS (I/P) FWFT (I/P)
WSDR (I/P)
RSDR (I/P)
TABLE 6 — I/O CONFIGURATION
17
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
SIGNAL DESCRIPTION
INPUTS:
DATA IN (D0 – Dn)
(D0 – D39) are data inputs for the 40-bit wide data, (D0 – D19) are data
inputs for the 20-bit wide data, or (D0 – D9) are data inputs for 10-bit wide data.
CONTROLS:
MASTER RESET (MRS)
A Master Reset is accomplished whenever the MRS input is taken to a LOW
state. This operation sets the internal read and write pointers to the first location
of the RAM array . PAE will go LOW and PAF will go HIGH.
If FWFT is LOW during Master Reset then IDT Standard mode along with
EF and FF are selected. EF will go LOW and FF will go HIGH, If FWFT is
HIGH, then the First Word Fall Through (FWFT) mode, along with IR and OR
are selected. OR will go HIGH and IR will go LOW.
All control settings such as OW, IW, BM, WSDR, RSDR, FSEL0 and FSEL1
are defined during the Master Reset cycle.
During a Master Reset the output register is initialized to all zeros. A Master
Reset is required after power up before a write operation can take place. MRS
is asynchronous.
See Figure 8, Master Reset Timing, for the relevant timing diagram.
P ARTIAL RESET (PRS)
A Partial Reset is accomplished whenever the PRS input is taken to a LOW
state. As in the case of the Master Reset, the internal read and write pointers
are set to the first location of the RAM array . PAE goes LOW and PAF goes
HIGH.
Whichever mode was active at the time of Partial Reset will remain active
after Partial Reset. If IDT Standard Mode is active, then FF will go HIGH and
EF will go LOW. If the First Word Fall Through mode is active, then OR will go
HIGH and IR will go LOW .
Following Partial Reset, all values held in the offset registers remain un-
changed. The output register is initialized to all zeroes. PRS is asynchronous.
Partial Reset is useful for resetting the read and write pointers to zero without
affecting the values of the programmable flag offsets and the timing mode of the
FIFO.
See Figure 9, Partial Reset Timing, for the relevant timing diagram.
RETRANSMIT (RT)
The Retransmit (RT) input is used in conjunction with the MARK input.
T ogether they provide a means by which data previously read out of the FIFO
can be reread any number of times. When the retransmit operation is selected
(i.e. after data has been marked), a rising edge on RCLK while RT is LOW will
reset the read pointer back to the memory location set by the user via the
MARK input.
If IDT Standard mode has been selected, the EF flag will go LOW on the
rising edge of RCLK that retransmit was initiated (i.e. rising edge of RCLK
while RT is LOW). EF will go back to HIGH on the next rising edge of RCLK,
which signifies that retransmit setup is complete. The next read operation will
access data from the “marked” memory location.
Subsequent retransmit operations may be performed, each time the read
pointer returning to the “marked” location. See Figure 23, Retransmit from
Mark in Double Data Rate Mode (IDT Standard Mode) for the relevant timing
diagram.
If FWFT mode has been selected, the OR flag will go HIGH on the rising
edge of RCLK that retransmit was initiated. OR will return LOW on the next
rising edge of RCLK, which signifies that retransmit setup is complete. Under
FWFT mode, the contents in the marked memory location will be loaded onto
the output register on the next rising edge of RCLK. To access all subsequent
data, a read operation will be required.
Subsequent retransmit operations may be performed, each time the read
pointer returning to the “marked” location. See Figure 24, Retransmit from
Mark (FWFT Mode) for the relevant timing diagram.
MARK
The MARK input is used to select Retransmit mode of operation. On a rising
edge of RCLK while MARK is HIGH will mark the memory location of the data
currently present on the output register, in addition placing the device in
retransmit mode. Note, there must be a minimum of 1280 bits (or 160 bytes) of
data between the write pointer and mark location. That is, 40 bits x32 for the
x40 mode, 20 bits x64 for the x20 mode, and 10 bits x128 for the x10 mode.
Also, once the MARK is set, the write pointer will not increment past the
“marked” location until the MARK is deasserted. This prevents “overwriting” of
retransmit data.
The MARK input must remain HIGH during the whole period of retransmit
mode, a rising edge of RCLK while MARK is LOW will take the device out of
retransmit mode and into normal mode. Any number of MARK locations can
be set during FIFO operation, only the last marked location taking effect. Once
a mark location has been set the write pointer cannot be incremented past this
marked location. During retransmit mode write operations to the device may
continue without hindrance.
FIRST WORD FALL THROUGH (FWFT)
During Master Reset, the state of the FWFT input determines whether the
device will operate in IDT Standard mode or First Word Fall Through (FWFT)
mode.
If, at the time of Master Reset, FWFT is LOW , then IDT Standard mode will
be selected. This mode uses the Empty Flag (EF) to indicate whether or not
there are any words present in the FIFO memory . It also uses the Full Flag
function (FF) to indicate whether or not the FIFO memory has any free space
for writing. In IDT Standard mode, every word read from the FIFO, including
the first, must be requested using the Read Enable (REN) and RCLK.
If, at the time of Master Reset, FWFT is HIGH, then FWFT mode will be
selected. This mode uses Output Ready (OR) to indicate whether or not there
is valid data at the outputs (Qn) to be read. It also uses Input Ready (IR) to
indicate whether or not the FIFO memory has any free space for writing. In the
FWFT mode, the first word written to an empty FIFO goes directly to Qn after
three RCLK rising edges, bringing REN LOW is not necessary . Subsequent
words must be accessed using the Read Enable (REN) and RCLK. Note that
FWFT mode can only be used when the device is configured to Single Data
Rate (SDR) mode.
WRITE CLOCK (WCLK)
A write cycle is initiated on the rising and/or falling edge of the WCLK input.
If the Write Single Data Rate (WSDR) pin is selected, data will be written only
on the rising edge of WCLK, provided that WEN and WCS are LOW . If the
WSDR is not selected, data will be written on both the rising and falling edge of
WCLK, provided that WEN and WCS are LOW . Data setup and hold times
must be met with respect to the LOW-to-HIGH transition of the WCLK. It is
permissible to stop the WCLK. Note that while WCLK is idle, the FF, IR, and
PAF flags will not be updated. The write and read clocks can either be
independent or coincident.
18
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
WRITE ENABLE (WEN)
When the WEN input is LOW, data may be loaded into the FIFO RAM array
on the rising edge of every WCLK cycle if the device is not full. Data is stored
in the RAM array sequentially and independently of any ongoing read opera-
tion.
When WEN is HIGH, no new data is written in the RAM array on each
WCLK cycle.
To prevent data overflow in the IDT Standard mode, FF will go LOW,
inhibiting further write operations. Upon the completion of a valid read cycle,
FF will go HIGH, allowing a write to occur . The FF is updated by two WCLK
cycles + tSKEW after the RCLK cycle.
To prevent data overflow in the FWFT mode, IR will go HIGH, inhibiting
further write operations. Upon the completion of a valid read cycle, IR will go
LOW , allowing a write to occur. The IR flag is updated by two WCLK cycles +
tSKEW after the valid RCLK cycle.
WEN is ignored when the FIFO is full in either IDT Standard mode or
FWFT.
WRITE SINGLE DA TA RA TE (WSDR)
When the Write Single Data Rate pin is LOW , the write port will be set to
Single Data Rate mode. In this mode, all write operations are based only on
the rising edge of WCLK, provided that WEN and WCS are LOW. When
WSDR is HIGH, the read port will be set to Double Data Rate mode. In this
mode, all write operations are based on both the rising and falling edge of
WCLK, provided that WEN and WCS are LOW, on the rising edge of WCLK.
READ CLOCK (RCLK)
A read cycle is initiated on the rising and/or falling edge of the RCLK input.
If the Read Single Data Rate (RSDR) pin is selected, data will be read only on
the rising edge of RCLK, provided that REN and RCS are LOW . If the RSDR
is not selected, data will be read on both the rising and falling edge of WCLK,
provided that REN and RCS are LOW, on the rising edge of RCLK. Setup and
hold times must be met with respect to the LOW-to-HIGH transition of the
RCLK. It is permissible to stop the RCLK. Note that while RCLK is idle, the EF/
OR and PAE flags will not be updated. Write and Read Clocks can be inde-
pendent or coincident.
READ ENABLE (REN)
When Read Enable is LOW , data is loaded from the RAM array into the
output register on the rising edge of every RCLK cycle if the device is not
empty.
When the REN input is HIGH, the output register holds the previous data
and no new data is loaded into the output register . The data outputs Q0-Qn
maintain the previous data value.
In IDT Standard mode, every word accessed at Qn, including the first word
written to an empty FIFO, must be requested using REN provided that the
Read Chip Select (RCS) is LOW. When the last word has been read from the
FIFO, the Empty Flag (EF) will go LOW , inhibiting further read operations.
REN is ignored when the FIFO is empty . Once a write is performed, EF will go
HIGH allowing a read to occur . Both RCS and REN must be active LOW for
data to be read out on the rising edge of RCLK.
In FWFT mode, the first word written to an empty FIFO automatically goes
to the outputs Qn, on the third valid LOW-to-HIGH transition of RCLK + tSKEW
after the first write. REN and RCS do not need to be asserted LOW for the First
Word to fall through to the output register . All subsequent words require that a
read operation to be executed using REN and RCS. The LOW-to-HIGH
transition of RCLK after the last word has been read from the FIFO will make
Output Ready (OR) go HIGH with a true read (RCLK with REN and RCS
LOW), inhibiting further read operations. REN is ignored when the FIFO is
empty.
READ SINGLE DATA RATE (RSDR)
When the Read Single Data Rate pin is LOW , the read port will be set to
Single Data Rate mode. In this mode, all read operations are based only on
the rising edge of RCLK, provided that REN and RCS are LOW. When RSDR
is HIGH, the read port will be set to Double Data Rate mode. In this mode, all
read operations are based on both the rising and falling edge of RCLK,
provided that REN and RCS are LOW , on the rising edge of RCLK.
SERIAL CLOCK (SCLK)
The serial clock is used to load and read data in the programmable offset
registers. Data from the Serial Input (SI) can be loaded into the offset registers
on the rising edge of SCLK provided that SEN is LOW . Data can be read from
the offset registers via the Serial Output (SO) on the rising edge of SCLK
provided that SREN is LOW. The serial clock can operate at a maximum
frequency of 10MHz and its parameters are different than the FIFO system
clock.
SERIAL ENABLE (SEN)
The SEN input is an enable used for serial programming of the program-
mable offset registers. It is used in conjunction with SI and SCLK when pro-
gramming the offset registers. When SEN is LOW , data at the Serial In (SI)
input can be loaded into the offset register, one bit for each LOW-to-HIGH
transition of SCLK.
When SEN is HIGH, the offset registers retain the previous settings and no
offsets are loaded. SEN functions the same way in both IDT Standard and
FWFT modes.
SERIAL READ ENABLE (SREN)
The SREN output is an enable used for reading the value of the program-
mable offset registers. It is used in conjunction with SI and SCLK when reading
from the offset registers. When SREN is LOW , data can be read out of the offset
register from the SO output, one bit for each LOW-to-HIGH transition of SCLK.
When SREN is HIGH, the reading of the offset registers will stop. When-
ever SREN is activated values in the offset registers are read starting from the
first location in the offset registers and not from where the last offset value was
read. SREN functions the same way in both IDT Standard and FWFT modes.
SERIAL IN (SI)
This pin acts as a serial input for loading PAE and PAF offsets into the
programmable offset registers. It is used in conjunction with the Serial Clock
(SCLK) and the Serial Enable (SEN). Data from this input can be loaded into
the offset register , one bit for each LOW-to-HIGH transition of SCLK provided
that SEN is LOW.
SERIAL OUT (SO)
This pin acts as a serial output for reading the values of the PAE and PAF
offsets in the programmable offset registers. It is used in conjunction with the
Serial Clock (SCLK) and the Serial Enable Output (SREN). Data from the
offset register can be read out using this pin, one-bit for each LOW-to-HIGH
transition of SCLK provided that SREN is LOW.
19
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
OUTPUT ENABLE (OE)
When Output Enable is LOW , the parallel output buffers receive data from
the output register . When OE is HIGH, the output data bus (Qn) goes into a
high-impedance state. During Master or Partial Reset the OE is the only input
that can place the output data bus into high-impedance. During reset the RCS
input can be HIGH or LOW and has no effect on the output data bus.
READ CHIP SELECT (RCS)
The Read Chip Select input provides synchronous control of the Read
output port. When RCS goes LOW , the next rising edge of RCLK causes the
Qn outputs to go to the low-impedance state. When RCS goes HIGH, the next
RCLK rising edge causes the Qn outputs to return to high-impedance. During
a Master or Partial Reset the RCS input has no effect on the Qn output bus, OE
is the only input that provides high-impedance control of the Qn outputs. If OE
is LOW, the Qn data outputs will be low-impedance regardless of RCS until the
first rising edge of RCLK after a reset is complete. Then if RCS is HIGH the
data outputs will go to high-impedance.
The RCS input does not effect the operation of the flags. For example, when
the first word is written to an empty FIFO, the EF will still go from LOW to HIGH
based on a rising edge of RCLK, regardless of the state of the RCS input.
Also, when operating the FIFO in FWFT mode the first word written to an
empty FIFO will still be clocked through to the output register based on RCLK,
regardless of the state of RCS. For this reason the user should pay extra
attention when a data word is written to an empty FIFO in FWFT mode. If RCS
is HIGH when an empty FIFO is written into, the first word will fall through to the
output register but will not be available on the Qn outputs because they are in
high-impedance. The user must take RCS active LOW to access this first word,
placing the output bus in low-impedance. REN must remain HIGH for at least
one cycle after RCS has gone LOW . A rising edge of RCLK with RCS and
REN LOW will read out the next word. Care must be taken so as not to lose the
first word written to an empty FIFO when RCS is HIGH. Refer to Figure 22,
RCS and REN Read Operation (FWFT Mode). The RCS pin must also be
active (LOW) in order to perform a Retransmit. See Figure 18 for Read Cycle
and Read Chip Select Timing (IDT Standard Mode). See Figure 21 for Read
Cycle and Read Chip Select Timing (FWFT Mode).
WRITE CHIP SELECT (WCS)
The WCS disables all Write Port inputs (data only) if it is held HIGH. To
perform normal operations on the write port, the WCS must be enabled.
HSTL SELECT (HSTL)
The inputs that were listed in Table 6 can be setup to be either HSTL or
LVTTL. If HSTL is HIGH, then HSTL operation of those signals will be se-
lected. If HSTL is LOW , then LVTTL will be selected.
BUS-MATCHING (BM, IW, OW)
The pins BM, IW, and OW are used to define the input and output bus
widths. During Master Reset, the state of these pins is used to configure the
device bus sizes. See Table 1 for control settings. All flags will operate on the
word/byte size boundary as defined by the selection of bus width. See Table
7 for Bus-Matching Write to Read Ratio.
FLAG SELECT BITS (FSEL0 and FSEL1)
These pins will select the four default offset values for the PAE and PAF flags
during Master Reset. The four possible settings are listed on T able 3. Note that
the status of these inputs should not change after Master Reset.
OUTPUTS:
DA T A OUT (Q0-Q39)
(Q0 – Q39) are data outputs for 40-bit wide data, (Q0 – Q19) are data
outputs for 20-bit wide data, or (Q0 – Q9) are data outputs for 10-bit wide data.
FULL FLAG (FF/IR)
This is a dual-purpose pin. In IDT Standard mode, the Full Flag (FF) function
is selected. When the FIFO is full, FF will go LOW, inhibiting further write
operations. When FF is HIGH, the FIFO is not full. If no reads are performed
after a reset (either MRS or PRS), FF will go LOW after D writes to the FIFO
(D = 16,384 for the IDT72T4088, 32,768 for the IDT72T4098, 65,536 for the
IDT72T40108, 131,072 for the IDT72T40118. See Figure 10, Write Cycle and
Full Flag Timing (IDT Standard Mode), for the relevant timing information.
In FWFT mode, the Input Ready (IR) function is selected. IR goes LOW when
memory space is available for writing in data. When there is no longer any free
space left, IR goes HIGH, inhibiting further write operations. If no reads are
performed after a reset (either MRS or PRS), IR will go HIGH after D writes to
the FIFO (D = 16,385 for the IDT72T4088, 32,769 for the IDT72T4098, 65,537
for the IDT72T40108, 131,073 for the IDT72T40118). See Figure 19, Write
Timing (FWFT Mode), for the relevant timing information.
The IR status not only measures the contents of the FIFO memory , but also
counts the presence of a word in the output register. Thus, in FWFT mode, the
total number of writes necessary to deassert IR is one greater than needed to
assert FF in IDT Standard mode.
FF/IR is synchronous and updated on the rising edge of WCLK. FF/IR are
double register-buffered outputs.
Note, when the device is in Retransmit mode, this flag is a comparison of the
write pointer to the “marked” location. This differs from normal mode where this
flag is a comparison of the write pointer to the read pointer.
EMPTY FLAG (EF/OR)
This is a dual-purpose pin. In the IDT Standard mode, the Empty Flag (EF)
function is selected. When the FIFO is empty, EF will go LOW, inhibiting further
read operations. When EF is HIGH, the FIFO is not empty. See Figure 12, Read
Cycle, Empty Flag and First Word Latency Timing (IDT Standard Mode), for
the relevant timing information.
In FWFT mode, the Output Ready (OR) function is selected. OR goes LOW
at the same time that the first word written to an empty FIFO appears valid on
the outputs. OR stays LOW after the RCLK LOW to HIGH transition that shifts the
last word from the FIFO memory to the outputs. OR goes HIGH only with a true
read (RCLK with REN = LOW). The previous data stays at the outputs, indicating
the last word was read. Further data reads are inhibited until OR goes LOW
again. See Figure 20, Read Timing (FWFT Mode), for the relevant timing
information.
EF/OR is synchronous and updated on the rising edge of RCLK.
In IDT Standard mode, EF is a double register-buffered output. In FWFT
mode, OR is a triple register-buffered output.
PROGRAMMABLE ALMOST-FULL FLAG (PAF)
The Programmable Almost-Full flag (PAF) will go LOW when the FIFO
reaches the almost-full condition. In IDT Standard mode, if no reads are
performed after reset (MRS), PAF will go LOW after (D - m) words are written
to the FIFO. The PAF will go LOW after (16,384-m) writes for the IDT72T4088,
(32,768-m) writes for the IDT72T4098, (65,536-m) writes for the IDT72T40108,
(131,072-m) writes for the IDT72T40118. The offset “m” is the full offset
value. The default setting for this value is listed in T able 3.
20
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
In FWFT mode, the PAF will go LOW after (16,385-m) writes for the
IDT72T4088, (32,769-m) writes for the IDT72T4098, (65,537-m) writes for the
IDT72T40108, (131,073-m) writes for the IDT72T40118. where m is the full
offset value. The default setting for this value is listed in Table 3.
See Figure 29, Programmable Almost-Full Flag Timing (IDT Standard and
FWFT Mode), for the relevant timing information.
Note, when the device is in Retransmit mode, this flag is a comparison of the
write pointer to the “marked” location. This differs from normal mode where this
flag is a comparison of the write pointer to the read pointer.
PROGRAMMABLE ALMOST-EMPTY FLAG (PAE)
The Programmable Almost-Empty flag (PAE) will go LOW when the FIFO
reaches the almost-empty condition. In IDT Standard mode, PAE will go LOW
when there are n words or less in the FIFO. The offset “n” is the empty offset
value. The default setting for this value is stated in the footnote of Table 3.
In FWFT mode, the PAE will go LOW when there are n+1 words or less in
the FIFO. The default setting for this value is stated in Table 3.
See Figure 30, Programmable Almost-Empty Flag Timing (IDT Standard
and FWFT Mode), for the relevant timing information.
ECHO READ CLOCK (ERCLK)
The Echo Read Clock output is provided in both HSTL and L VTTL mode,
selectable via HSTL. The ERCLK is a free-running clock output, it will always
follow the RCLK input regardless of REN and RCS.
The ERCLK output follows the RCLK input with an associated delay . This
delay provides the user with a more effective read clock source when reading
data from the Qn outputs. This is especially helpful at high speeds when
variables within the device may cause changes in the data access times.
These variations in access time maybe caused by ambient temperature, sup-
ply voltage, or device characteristics. The ERCLK output also compensates
for any trace length delays between the Qn data outputs and receiving de-
vices inputs.
Any variations effecting the data access time will also have a corresponding
effect on the ERCLK output produced by the FIFO device, therefore the
ERCLK output level transitions should always be at the same position in time
relative to the data outputs. Note, that ERCLK is guaranteed by design to be
slower than the slowest Qn, data output. Refer to Figure 4, Echo Read Clock
and Data Output Relationship, Figure 27, Echo Read Clock & Read Enable
Operation in Double Data Rate Mode and Figure 28, Echo RCLK & Echo
REN Operation for timing information.
ECHO READ ENABLE (EREN)
The Echo Read Enable output is provided in both HSTL and LVTTL mode,
selectable via HSTL.
The EREN output is provided to be used in conjunction with the ERCLK
output and provides the reading device with a more effective scheme for
reading data from the Qn output port at high speeds. The EREN output is
controlled by internal logic that behaves as follows: The EREN output is active
LOW for the RCLK cycle that a new word is read out of the FIFO. That is, a
rising edge of RCLK will cause EREN to go active, LOW if both REN and RCS
are active, LOW and the FIFO is NOT empty .
Figure 4. Echo Read Clock and Data Output Relationship
NOTES:
1. REN is LOW.
2. tERCLK > tA, guaranteed by design.
3. Qslowest is the data output with the slowest access time, tA.
4. Time, tD is greater than zero, guaranteed by design.
5. REN = RCS = OE = 0.
5995 drw07
ERCLK
tA
QSLOWEST
(3)
RCLK
tERCLK
tERCLK
tAtDtD
21
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
TABLE 7 — BUS-MATCHING WRITE TO READ RATIO
ONE WRITE TO ONE READ (1:1)
Configuration
WSDR RSDR BM IW OW
HHLLL
DDR Write Clock x40 Data In DDR Read Clock x40 Data Out
Positive Edge 1 D[39:0] <= L W1 Positive Edge 1 Q[39:0] <= L W1
Negative Edge 1 D[39:0] <= L W2 Negative Edge 1 Q[39:0] <= L W2
x40 DDR Input to x40 DDR Output Configuration
WSDR RSDR BM IW OW
LLLLL
SDR Write Clock x40 Data In SDR Read Clock x40 Data Out
Positive Edge 1 D[39:0] <= L W1 Positive Edge 1 Q[39:0] <= L W1
x40 SDR Input to x40 SDR Output
Configuration
WSDR RSDR BM IW OW
LHHLL
x40 SDR Input to x20 DDR Output x20 DDR Input to x40 SDR Output
ONE WRITE TO TWO READ (1:2)
Configuration
WSDR RSDR BM IW OW
HLLLL
x40 DDR Input to x40 SDR Output
Configuration
WSDR RSDR BM IW OW
HHHLL
DDR Write Clock x40 Data In DDR Read Clock x20 Data Out
Positive Edge 1 D[39:20] <= L W1 Positive Edge 1 Q[19:0] <= L W1
D[19:0] <= L W2 Negative Edge 1 Q[19:0] <= L W2
Negative Edge 1 D[39:20] <= L W3 Positive Edge 2 Q[19:0] <= L W3
D[19:0] <= L W4 Negative Edge 2 Q[19:0] <= L W4
x40 DDR Input to x20 DDR Output
SDR Write Clock x40 Data In DDR Read Clock x20 Data Out
Positive Edge 1 D[39:20] <= W1 Positive Edge 1 Q[19:0] <= W1
D[19:0] <= W2 Negative Edge 1 Q[19:0] <= W2
DDR Write Clock x20 Data In SDR Read Clock x40 Data Out
Positive Edge 1 D[19:0] <= W1 Positive Edge 1 Q[39:20] <= W1
Negative Edge 1 D[19:0] <= W2 Q[19:0] <= W2
DDR Write Clock x40 Data In SDR Read Clock x40 Data Out
Positive Edge 1 D[39:0] <= L W1 Positive Edge 1 Q[39:0] <= L W1
Negative Edge 1 D[39:0] <= L W2 Positive Edge 2 Q[39:0] <= L W1
Configuration
WSDR RSDR BM IW OW
LLHLL
x40 SDR Input to x20 SDR Output
SDR Write Clock x40 Data In SDR Read Clock x20 Data Out
Positive Edge 1 D[39:20] <= L W1 Positive Edge 1 Q[19:0] <= L W1
D[19:0] <= L W2 Positive Edge 2 Q[19:0] <= L W2
Configuration
WSDR RSDR BM IW OW
LHHLH
SDR Write Clock x40 Data In DDR Read Clock x10 Data Out
Positive Edge 1 D[39:30] <= B1 Positive Edge 1 Q[9:0] <= B1
D[29:20] <= B2 Negative Edge 1 Q[9:0] <= B2
D[19:10] <= B3 Positive Edge 2 Q[9:0] <= B3
D[9:0] <= B4 Negative Edge 2 Q[9:0] <= B4
x40 SDR Input to x10 DDR Output
Configuration
WSDR RSDR BM IW OW
HLHHL
22
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
TABLE 7 — BUS-MATCHING WRITE TO READ RATIO (CONTINUED)
ONE WRITE TO FOUR READ (1:4)
Configuration
WSDR RSDR BM IW OW
HLHLL
x40 DDR Input to x20 SDR Output
ONE WRITE TO EIGHT READ (1:8)
Configuration
WSDR RSDR BM IW OW
HLHLH
x40 DDR Input to x10 SDR Output
DDR Write Clock x40 Data In SDR Read Clock x20 Data Out
Positive Edge 1 D[39:20] <= L W1 Positive Edge 1 Q[19:0] <= L W1
D[19:0] <= L W2 Positive Edge 2 Q[19:0] <= L W2
Negative Edge 1 D[39:20] <= L W3 Positive Edge 3 Q[19:0] <= L W3
D[19:0] <= L W4 Positive Edge 4 Q[19:0] <= L W4
Configuration
WSDR RSDR BM IW OW
LLHLH
x40 SDR Input to x10 SDR Output
SDR Write Clock x40 Data In SDR Read Clock x10 Data Out
Positive Edge 1 D[39:30] <= B1 Positive Edge 1 Q[9:0] <= B1
D[29:20] <= B2 Positive Edge 2 Q[9:0] <= B2
D[19:10] <= B3 Positive Edge 3 Q[9:0] <= B3
D[9:0] <= B4 Positive Edge 4 Q[9:0] <= B4
Configuration
WSDR RSDR BM IW OW
HHHLH
x40 DDR Input to x10 DDR Output
DDR Write Clock x40 Data In SDR Read Clock x10 Data Out
Positive Edge 1 D[39:30] <= B1 Positive Edge 1 Q[9:0] <= B1
D[29:20]<= B2 Negaitive Edge 1 Q[9:0] <= B2
D[19:10] <= B3 Positive Edge 2 Q[9:0] <= B3
D[9:0] <= B4 Negaitive Edge 2 Q[9:0] <= B4
Negative Edge 1 D[39:30] <= B5 Positive Edge 3 Q[9:0] <= B5
D[29:20]<= B6 Negaitive Edge 3 Q[9:0] <= B6
D[19:10] <= B7 Positive Edge 4 Q[9:0] <= B7
D[9:0] <= B8 Negaitive Edge 4 Q[9:0] <= B8
DDR Write Clock x40 Data In SDR Read Clock x10 Data Out
Positive Edge 1 D[39:30] <= B1 Positive Edge 1 Q[9:0] <= B1
D[29:20]<= B2 Positive Edge 2 Q[9:0] <= B2
D[19:10] <= B3 Positive Edge 3 Q[9:0] <= B3
D[9:0] <= B4 Positive Edge 4 Q[9:0] <= B4
Negative Edge 1 D[39:30] <= B5 Positive Edge 5 Q[9:0] <= B5
D[29:20]<= B6 Positive Edge 6 Q[9:0] <= B6
D[19:10] <= B7 Positive Edge 7 Q[9:0] <= B7
D[9:0] <= B8 Positive Edge 8 Q[9:0] <= B8
23
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
TABLE 7 — BUS-MATCHING WRITE TO READ RATIO (CONTINUED)
TWO WRITE TO ONE READ (2:1)
Configuration
WSDR RSDR BM IW OW
LHLLL
x40 SDR Input to x40 DDR Output
SDR Write Clock x40 Data In DDR Read Clock x40 Data Out
Positive Edge 1 D[39:0] <= L W1 Positive Edge 1 Q[39:0] <= L W1
Positive Edge 2 D[39:0] <= L W2 Negative Edge 1 Q[39:0] <= L W2
Configuration
WSDR RSDR BM IW OW
HHHHL
x20 DDR Input to x40 DDR Output
DDR Write Clock x20 Data In DDR Read Clock x40 Data Out
Positive Edge 1 D[19:0] <= W1 Positive Edge 1 Q[39:20] <= W1
Negative Edge 1 D[19:0] <= W2 Q[19:0] <= W2
Positive Edge 2 D[19:0] <= W3 Negative Edge 1 Q[39:20] <= W3
Negative Edge 2 D[19:0] <= W4 Q[19:0] <= W4
Configuration
WSDR RSDR BM IW OW
LLHHL
x20 SDR Input to x40 SDR Output
SDR Write Clock x20 Data In SDR Read Clock x40 Data Out
Positive Edge 1 D[19:0] <= W1 Positive Edge 1 Q[39:20] <= W1
Positive Edge 2 D[19:0] <= W2 Q[19:0] <= W2
Configuration
WSDR RSDR BM IW OW
HLHHH
x10 DDR Input to x40 SDR Output
DDR Write Clock x10 Data In SDR Read Clock x40 Data Out
Positive Edge 1 D[9:0] <= B1 Positive Edge 1 Q[39:30] <= B1
Negative Edge 1 D[9:0] <= B2 Q[29:20] <= B2
Positive Edge 2 D[9:0] <= B3 Q[19:10] <= B3
Negative Edge 2 D[9:0] <= B4 Q[9:0] <= B4
FOUR WRITE TO ONE READ (4:1)
Configuration
WSDR RSDR BM IW OW
LHHHL
x20 SDR Input to x40 DDR Output
SDR Write Clock x20 Data In DDR Read Clock x40 Data Out
Positive Edge 1 D[19:0] <= W1 Positive Edge 1 Q[39:20] <= W1
Positive Edge 2 D[19:0] <= W2 Q[19:0] <= W2
Positive Edge 3 D[19:0] <= W3 Negative Edge 1 Q[39:20] <= W3
Positive Edge 4 D[19:0] <= W4 Q[19:0] <= W4
Configuration
WSDR RSDR BM IW OW
HHHHH
x10 DDR Input to x40 DDR Output
DDR Write Clock x10 Data In DDR Read Clock x40 Data Out
Positive Edge 1 D[9:0] <= B1 Positive Edge 1 Q[39:30] <= B1
Negative Edge 1 D[9:0] <= B2 Q[29:20] <= B2
Positive Edge 2 D[9:0] <= B3 Q[19:10] <= B3
Negative Edge 2 D[9:0] <= B4 Q[9:0] <= B4
Positive Edge 3 D[9:0] <= B5 Negative Edge 2 Q[39:30] <= B5
Negative Edge 3 D[9:0] <= B6 Q[29:20] <= B6
Positive Edge 4 D[9:0] <= B7 Q[19:10] <= B7
Negative Edge 4 D[9:0] <= B8 Q[9:0] <= B8
Configuration
WSDR RSDR BM IW OW
LLHHH
x10 SDR Input to x40 SDR Output
SDR Write Clock x10 Data In SDR Read Clock x40 Data Out
Positive Edge 1 D[9:0] <= B1 Positive Edge 1 Q[39:30] <= B1
Positive Edge 2 D[9:0] <= B2 Q[29:20] <= B2
Positive Edge 3 D[9:0] <= B3 Q[19:10] <= B3
Positive Edge 4 D[9:0] <= B4 Q[9:0] <= B4
24
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
TABLE 7 — BUS-MATCHING WRITE TO READ RATIO (CONTINUED)
EIGHT WRITE TO ONE READ (8:1)
Configuration
WSDR RSDR BM IW OW
LHHHH
x10 SDR Input to x40 DDR Output
SDR Write Clock x10 Data In DDR Read Clock x40 Data Out
Positive Edge 1 D[9:0] <= B1 Positive Edge Q[39:30] <= B1
Positive Edge 2 D[9:0] <= B2 Q[29:20] <= B2
Positive Edge 3 D[9:0] <= B3 Q[19:10] <= B3
Positive Edge 4 D[9:0] <= B4 Q[9:0] <= B4
Positive Edge 5 D[9:0] <= B5 Negative Edge Q[39:30] <= B5
Positive Edge 6 D[9:0] <= B6 Q[29:20] <= B6
Positive Edge 7 D[9:0] <= B7 Q[19:10] <= B7
Positive Edge 8 D[9:0] <= B8 Q[9:0] <= B8
TABLE 8 — TSKEW MEASUREMENT
Data Port Status Flags TSKEW Measurement
Configuration
DDR Input EF & PAE Negative Edge WCLK to
t o Positive Edge RCLK
DDR Output FF & PAF Negative Edge RCLK to
Positive Edge WCLK
DDR Input EF & PAE Negative Edge WCLK to
t o Positive Edge RCLK
SDR Output FF & PAF Positive Edge RCLK to
Positive Edge WCLK
SDR Input EF & PAE Positive Edge WCLK to
t o Positive Edge RCLK
DDR Output FF & PAF Negative Edge RCLK to
Positive Edge WCLK
SDR Input EF & PAE Positive Edge WCLK to
t o Positive Edge RCLK
SDR Output FF & PAF Positive Edge RCLK to
Positive Edge WCLK
25
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 5. Standard JTAG Timing
SYSTEM INTERFACE PARAMETERS
Parameter Symbol Test
Conditions Min. Max. Units
JTAG Clock Input Period tTCK - 100 - ns
JTAG Clock HIGH tTCKHIGH -40-ns
JTAG Clock Low tTCKLOW -40-ns
JTAG Clock Rise Time tTCKRISE --5
(1) ns
JTAG Clock Fall Time tTCKFALL --5
(1) ns
JTAG Reset tRST -50-ns
JTAG Reset Recovery tRSR -50-ns
JTAG
AC ELECTRICAL CHARACTERISTICS
(vcc = 2.5V ± 5%; Tcase = 0°C to +85°C)
IDT72T4088
IDT72T4098
IDT72T40108
IDT72T40118
Parameter Symbol Test Conditions Min. Max. Units
Data Output tDO(1) -20ns
Data Output Hold tDOH(1) 0-ns
Data Input tDS trise=3ns 10 - ns
tDH tfall=3ns 10 -
NOTE:
1. 50pf loading on external output signals.
JTAG TIMING SPECIFICATION
NOTE:
1. Guaranteed by design.
t4
t3
TDO
TDO
TDI/
TMS
TCK
TRST
t
DO
Notes to diagram:
t1 =
t
TCKLOW
t2 =
t
TCKHIGH
t3 =
t
TCKFALL
t4 = t
TCKRISE
t5 =
tRST
(reset pulse width)
t6 = tRSR (reset recovery)
5995 drw08
t5
t6
t1t2
t
TCK
t
DH
t
DS
26
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
JTAG INTERFACE
Five additional pins (TDI, TDO, TMS, TCK and TRST) are provided to
support the JTAG boundary scan interface. The IDT72T4088/72T4098/
72T40108/72T40118 incorporates the necessary tap controller and modified
pad cells to implement the JTAG facility.
Note that IDT provides appropriate Boundary Scan Description Language
program files for these devices.
The Standard JTAG interface consists of four basic elements:
•Test Access Port (TAP)
•TAP controller
•Instruction Register (IR)
•Data Register Port (DR)
The following sections provide a brief description of each element. For a
complete description refer to the IEEE Standard Test Access Port Specification
(IEEE Std. 1149.1-1990).
The Figure below shows the standard Boundary-Scan Architecture
Figure 6. Boundary Scan Architecture
TEST ACCESS PORT (TAP)
The Tap interface is a general-purpose port that provides access to the
internal of the processor. It consists of four input ports (TCLK, TMS, TDI, TRST)
and one output port (TDO).
THE TAP CONTROLLER
The Tap controller is a synchronous finite state machine that responds to
TMS and TCLK signals to generate clock and control signals to the Instruction
and Data Registers for capture and update of data.
T
A
P
TAP
Cont-
roller
Mux
DeviceID Reg.
Boundary Scan Reg.
Bypass Reg.
clkDR, ShiftDR
UpdateDR
TDO
TDI
TMS
TCLK
TRST
clklR, ShiftlR
UpdatelR
Instruction Register
Instruction Decode
Control Signals
5995 drw09
27
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 7. TAP Controller State Diagram
Test-Logic
Reset
Run-Test/
Idle
1
0
0
Select-
DR-Scan
Select-
IR-Scan
111
Capture-IR
0
Capture-DR
0
0
EXit1-DR
1
Pause-DR
0
Exit2-DR
1
Update-DR
1
Exit1-IR
1
Exit2-IR
1
Update-IR
1
10
1
1
1
5995 drw10
0
Shift-DR
0
0
0
Shift-IR
0
0
Pause-IR
0
1
Input = TMS
0
01
Refer to the IEEE Standard Test Access Port Specification (IEEE Std.
1149.1) for the full state diagram
All state transitions within the TAP controller occur at the rising edge of the
TCLK pulse. The TMS signal level (0 or 1) determines the state progression
that occurs on each TCLK rising edge. The TAP controller takes precedence
over the FIFO memory and must be reset after power up of the device. See
TRST description for more details on TAP controller reset.
Test-Logic-Reset All test logic is disabled in this controller state enabling the
normal operation of the IC. The TAP controller state machine is designed in such
a way that, no matter what the initial state of the controller is, the Test-Logic-Reset
state can be entered by holding TMS at high and pulsing TCK five times. This
is the reason why the Test Reset (TRST) pin is optional.
Run-Test-Idle In this controller state, the test logic in the IC is active only if
certain instructions are present. For example, if an instruction activates the self
test, then it will be executed when the controller enters this state. The test logic
in the IC is idles otherwise.
Select-DR-Scan This is a controller state where the decision to enter the
Data Path or the Select-IR-Scan state is made.
Select-IR-Scan This is a controller state where the decision to enter the
Instruction Path is made. The Controller can return to the Test-Logic-Reset state
other wise.
Capture-IR In this controller state, the shift register bank in the Instruction
Register parallel loads a pattern of fixed values on the rising edge of TCK. The
last two significant bits are always required to be “01”.
Shift-IR In this controller state, the instruction register gets connected
between TDI and TDO, and the captured pattern gets shifted on each rising edge
of TCK. The instruction available on the TDI pin is also shifted in to the instruction
register.
Exit1-IR This is a controller state where a decision to enter either the Pause-
IR state or Update-IR state is made.
Pause-IR This state is provided in order to allow the shifting of instruction
register to be temporarily halted.
Exit2-DR This is a controller state where a decision to enter either the Shift-
IR state or Update-IR state is made.
Update-IR In this controller state, the instruction in the instruction register is
latched in to the latch bank of the Instruction Register on every falling edge of
TCK. This instruction also becomes the current instruction once it is latched.
Capture-DR In this controller state, the data is parallel loaded in to the data
registers selected by the current instruction on the rising edge of TCK.
Shift-DR, Exit1-DR, Pause-DR, Exit2-DR and Update-DR These
controller states are similar to the Shift-IR, Exit1-IR, Pause-IR, Exit2-IR and
Update-IR states in the Instruction path.
NOTES:
1. Five consecutive TCK cycles with TMS = 1 will reset the TAP.
2. TAP controller does not automatically reset upon power-up. The user must provide a reset to the TAP controller (either by TRST or TMS).
3. TAP controller must be reset before normal FIFO operations can begin.
28
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
THE INSTRUCTION REGISTER
The Instruction register allows an instruction to be shifted in serially into the
processor at the rising edge of TCLK.
The Instruction is used to select the test to be performed, or the test data
register to be accessed, or both. The instruction shifted into the register is latched
at the completion of the shifting process when the TAP controller is at Update-
IR state.
The instruction register must contain 4 bit instruction register-based cells
which can hold instruction data. These mandatory cells are located nearest the
serial outputs they are the least significant bits.
TEST DATA REGISTER
The Test Data register contains three test data registers: the Bypass, the
Boundary Scan register and Device ID register.
These registers are connected in parallel between a common serial input
and a common serial data output.
The following sections provide a brief description of each element. For a
complete description, refer to the IEEE Standard Test Access Port Specification
(IEEE Std. 1149.1-1990).
TEST BYPASS REGISTER
The register is used to allow test data to flow through the device from TDI
to TDO. It contains a single stage shift register for a minimum length in serial path.
When the bypass register is selected by an instruction, the shift register stage
is set to a logic zero on the rising edge of TCLK when the TAP controller is in
the Capture-DR state.
The operation of the bypass register should not have any effect on the
operation of the device in response to the BYPASS instruction.
THE BOUNDARY-SCAN REGISTER
The Boundary Scan Register allows serial data TDI be loaded in to or read
out of the processor input/output ports. The Boundary Scan Register is a part
of the IEEE 1149.1-1990 Standard JTAG Implementation.
THE DEVICE IDENTIFICATION REGISTER
The Device Identification Register is a Read Only 32-bit register used to
specify the manufacturer, part number and version of the processor to be
determined through the TAP in response to the IDCODE instruction.
IDT JEDEC ID number is 0xB3. This translates to 0x33 when the parity
is dropped in the 11-bit Manufacturer ID field.
For the IDT72T4088/72T4098/72T40108/72T40118, the Part Number
field contains the following values:
IDT72T4088/4098/40108/40118 JTAG Device Identification Register
31(MSB) 28 27 12 11 1 0(LSB)
V ersion (4 bits) Part Number (16-bit) Manufacturer ID (1 1-bit)
0X0 0X33 1
JTAG INSTRUCTION REGISTER
The Instruction register allows instruction to be serially input into the device
when the TAP controller is in the Shift-IR state. The instruction is decoded to
perform the following:
•Select test data registers that may operate while the instruction is
current. The other test data registers should not interfere with chip
operation and the selected data register.
•Define the serial test data register path that is used to shift data between
TDI and TDO during data register scanning.
The Instruction Register is a 4 bit field (i.e.IR3, IR2, IR1, IR0) to decode 16
different possible instructions. Instructions are decoded as follows.
Hex Instruction Function
Value
0x02 IDCODE Select Chip Identification data register
0x01 SAMPLE/PRELOAD Select Boundary Scan Register
0x03 HI-IMPEDANCE JTAG
0x0F BYPASS Select Bypass Register
Table 8. JTAG Instruction Register Decoding
The following sections provide a brief description of each instruction. For
a complete description refer to the IEEE Standard Test Access Port Specification
(IEEE Std. 1149.1-1990).
IDCODE
The optional IDCODE instruction allows the IC to remain in its functional mode
and selects the optional device identification register to be connected between
TDI and TDO. The device identification register is a 32-bit shift register containing
information regarding the IC manufacturer, device type, and version code.
Accessing the device identification register does not interfere with the operation
of the IC. Also, access to the device identification register should be immediately
available, via a TAP data-scan operation, after power-up of the IC or after the
TAP has been reset using the optional TRST pin or by otherwise moving to the
Test-Logic-Reset state.
SAMPLE/PRELOAD
The required SAMPLE/PRELOAD instruction allows the IC to remain in a
normal functional mode and selects the boundary-scan register to be connected
between TDI and TDO. During this instruction, the boundary-scan register can
be accessed via a date scan operation, to take a sample of the functional data
entering and leaving the IC.
HIGH-IMPEDANCE
The optional High-Impedance instruction sets all outputs (including two-state
as well as three-state types) of an IC to a disabled (high-impedance) state and
selects the one-bit bypass register to be connected between TDI and TDO.
During this instruction, data can be shifted through the bypass register from TDI
to TDO without affecting the condition of the IC outputs.
BYPASS
The required BYPASS instruction allows the IC to remain in a normal
functional mode and selects the one-bit bypass register to be connected
between TDI and TDO. The BYPASS instruction allows serial data to be
transferred through the IC from TDI to TDO without affecting the operation of
the IC.
EXTEST
The required EXTEST instruction is not available for this device.
Device Part# Field
IDT72T4088 04A3
IDT72T4098 04A2
IDT72T40108 04A1
IDT72T40118 04A0
29
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 8. Master Reset Timing
NOTES:
1 . During Master Reset the High-Impedance control of the Qn data outputs is provided by OE only, RCS can be HIGH or LOW until the first rising edge of RCLK after Master Reset
is complete.
2. The status of these pins are latched in when the Master Reset pulse is LOW.
5995 drw11
RT
SEN
t
RSF
t
RSF
OE = HIGH
OE = LOW
PAE
PAF
Q
0
- Q
n
t
RSF
EF/OR
FF/IR
t
RSF
t
RSF
If FWFT = HIGH, OR = HIGH
If FWFT = LOW, EF = LOW
If FWFT = LOW, FF = HIGH
If FWFT = HIGH, IR = LOW
t
RSS
t
RSS
SREN
t
RSS
t
RS
MRS
t
RSR
REN
t
RSS
FWFT
(2)
t
RSR
t
RSR
WEN
FSEL0
(2)
,
FSEL1
OW
(2)
,
IW, BM
t
RSS
t
RSS
t
RSS
t
RSS
t
HRSS
HSTL
(2)
WSDR
(2)
t
RSR
t
RSS
RSDR
(2)
t
RSR
t
RSS
30
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 9. Partial Reset Timing
NOTE:
1 . During Partial Reset the High-Impedance control of the Qn data outputs is provided by OE only, RCS can be HIGH or LOW until the first rising edge of RCLK after Master Reset
is complete.
t
RS
PRS
t
RSR
REN
t
RSS
5995 drw12
t
RSR
WEN
RT
SEN
t
RSF
t
RSF
OE = HIGH
OE = LOW
PAE
PAF
Q
0
- Q
n
t
RSF
EF/OR
FF/IR
t
RSF
t
RSF If FWFT = HIGH, OR = HIGH
If FWFT = LOW, EF = LOW
If FWFT = LOW, FF = HIGH
If FWFT = HIGH, IR = LOW
t
RSS
t
RSS
t
RSS
SREN
t
RSS
31
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 10. Write Cycle and Full Flag Timing (IDT Standard Mode)
NOTES:
1. tSKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that FF will go HIGH (after one WCLK cycle plus tWFF). If the time between the
rising edge of the RCLK and the rising edge of the WCLK is less than tSKEW1, then the FF deassertion may be delayed one extra WCLK cycle.
2. OE = LOW, EF = HIGH.
3. WCS = LOW.
4. WCLK must be free running for FF to update.
D
0
- D
39
WEN
RCLK
REN
t
ENH
t
ENH
Q
0
- Q
39 DATA READ NEXT DATA READ
t
SKEW1
(1)
5995 drw13
WCLK
NO WRITE
1212
NO WRITE
t
WFF
t
A
t
ENS
t
ENS
(1)
t
DS
t
A
D
X
t
DH
t
CLK1
t
CLKH1
FF
RCS
t
ENS
t
RCSLZ
t
WFF
t
SKEW1
t
CLKL1
D
X+1
t
WFF
t
WFF
t
DS
t
DH
32
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 11. Write Cycle and Full Flag Timing in Double Data Rate Mode (IDT Standard Mode)
NOTES:
1. tSKEW2 is the minimum time between a falling RCLK edge and a rising WCLK edge to guarantee that FF will go HIGH (after one WCLK cycle plus tWFF). If the time between the falling edge of the RCLK and the rising edge of WCLK
is less than tSKEW2, then FF deassertion may be delayed one extra WCLK cycle.
2. OE = LOW, EF = HIGH.
3. WCS = LOW, RCS = LOW, WSDR = HIGH and RSDR = HIGH.
4. WCLK must be free running for FF to update.
Data Read
Q
0
-Q39
5995 drw14
t
A
12
NO WRITE
D
0-
D39
RCLK
WCLK
WEN
FF
t
CLKL2
t
CLKH2
t
CLK2
t
SKEW2
(1)
12
t
SKEW2
(1)
REN
NO WRITE
Dx
t
DS
t
DS
t
DH
Dx+1
t
DH
Dx+2 Dx+3
t
WFF
t
WFF
t
WFF
t
WFF
t
ENH
t
ENS
t
ENH
t
ENS
t
A
Data in Output Register Next Data Read Next Data
t
A
t
A
Next Data Read
33
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 12. Read Cycle, Output Enable, Empty Flag and First Data Word Latency (IDT Standard Mode)
NOTES:
1. tSKEW1 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that EF will go HIGH (after one RCLK cycle plus tREF). If the time between the
rising edge of WCLK and the rising edge of RCLK is less than tSKEW1, then EF deassertion may be delayed one extra RCLK cycle.
2. First data word latency = tSKEW1 + 1*TRCLK + tREF.
3. RCS is LOW.
4. RCLK must be free running for EF to update.
5995 drw15
D
0
- D
39
t
DS
t
DH
D
0
D
1
t
DS
t
DH
NO OPERATION
RCLK
REN
EF
t
CLK1
t
ENH
t
REF
t
A
t
OLZ
Q
0
- Q
39
OE
WCLK
(1)
tSKEW1
WEN
t
ENS
t
ENS
t
ENH
12
t
OLZ
NO OPERATION
LAST WORD D
0
D
1
t
ENS
t
ENH
t
OHZ
LAST WORD
t
REF
t
ENH
t
ENS
t
A
t
A
t
REF
t
ENS
t
ENH
WCS
t
OE
t
WCSS
t
WCS
H
t
CLKH1
t
CLKL1
34
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 13. Read Cycle, Output Enable, Empty Flag and First Data Word Latency in Double Data Rate Mode (IDT Standard Mode)
NOTES:
1. tSKEW2 is the minimum time between a falling WCLK edge and a rising RCLK edge to guarantee that EF will go HIGH (after one RCLK cycle plus tREF). If the time between the falling edge of WCLK and the rising edge of RCLK
is less than tSKEW2, then EF deassertion may be delayed one extra RCLK cycle.
2. REN = LOW.
3. First data word latency = tSKEW1 + 1*tRCLK + tREF.
4. RCS = LOW, WSDR = HIGH and RSDR = HIGH.
5. RCLK must be free running for EF to update.
t
OLZ
tREF tREF
D
n
D
n
D
0
tA
D
1
tOHZ tOLZ
Q0-Q39
EF
OE
WCLK
WEN
D0-D39
5995 drw16
D
0
D
1
tDH tDS
tDS tDH
tENS tENH
tREF
tA
RCLK
12
tSKEW2
(1)
tCLK2
tCLKH2
tOE
tA
WCS
tWCSS tWCSH
tA
D
n
-
1
NO Read NO Read NO Read NO Read
tCLKL2
35
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 14. Read Cycle, Empty Flag and First Data Word Latency in x40DDR to x10SDR with Bus-Matching and Rate-Matching (IDT Standard Mode)
RCLK
EF
WEN
REN
WCS
tENS
tSKEW2(1)
D0-D39
tDS
W0 - W3
Q0-Q9
WCLK tENH
twcSH
tWCSS
W4 - W7
tDH tDS tDH
12
tREF
tENS
tAtAtAtAtA
W0 W1 W2
tAtAtA
W3 W4 W5 W6 W7
tENH
tREF
Previous Data in Ouput Register
5995 drw17
NOTES:
1. tSKEW2 is the minimum time between a falling WCLK edge and a rising RCLK edge to guarantee that EF will go HIGH (after one RCLK cycle plus tREF). If the time between the falling edge of WCLK and the rising edge of RCLK
is less than tSKEW2, then EF deassertion may be delayed one extra RCLK cycle.
2. REN = LOW.
3. First data word latency = tSKEW1 + 1*tRCLK + tREF.
4. RCS = LOW, WSDR = HIGH and RSDR = HIGH.
5. RCLK must be free running for EF to update.
36
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 15. Read Cycle and Empty Flag in x20SDR to x40DDR with Bus-Matching and Rate-Matching (IDT Standard Mode)
NOTES:
1. tSKEW1 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that EF will go HIGH (after one RCLK cycle plus tREF). If the time between the rising edge of WCLK and the rising edge of RCLK is
less than tSKEW1, then EF deassertion may be delayed one extra RCLK cycle.
2. OE = LOW.
3. First data word latency = tSKEW1 + 1*tRCLK + tREF.
4. RCS = LOW, WCS = LOW, WSDR = LOW and RSDR = HIGH.
5. RCLK must be free running for EF to update.
Q
0-
Q
39
t
SKEW
(1)
WCLK
RCLK
REN
12
WEN
t
REF
EF
D
0
-D
19
5995 drw18
t
REF
t
REF
Last Word Last 40-bit Word
t
ENS
t
ENH
W
0
W
1
W
2
W
3
t
ENH
t
ENS
W
0
-W
1
t
A
t
A
t
A
t
A
t
DS
t
DH
t
DS
t
DH
t
DS
t
DH
t
DH
t
DS
t
CLK2
t
CLKH2
t
CLKL2
Previous Data
t
ENH
NO Read
W
2
-W
3
37
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 16. Write Cycle and Full Flag Timing in x20DDR to x40SDR with Bus-Matching and Rate-Matching (IDT Standard Mode)
WCLK
FF
WEN
RCS
tENS
tSKEW1(1)
Q0-Q39
RCLK
tENH
tENS
12
tWFF
D0-D19
REN
tRCSLZ
tA
tDS tDStDH tDH
tWFF
tSKEW1(1)
tENS tENH
tA
12
tWFF
tDS tDStDH tDH
tCLK2
tCLKH2 tCLKL2
NO WRITE
NO WRITE
tWFF
DATA READ NEXT DATA READ
Wx Wx+1 Wx+2 Wx+3
5995 drw19
NOTES:
1. tSKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that FF will go HIGH (after one WCLK cycle plus tWFF). If the time between the rising edge of the RCLK and the rising edge of the
WCLK is less than tSKEW1, then the FF deassertion may be delayed one extra WCLK cycle.
2. LD = HIGH, OE = LOW, EF = HIGH.
3. WCS = LOW.
4. WCLK must be free running for FF to update.
38
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 17. Write Cycle and Full Flag in x40SDR to x20DDR with Bus-Matching and Rate-Matching (IDT Standard Mode)
WCLK
FF
WEN
RCS
t
ENS
Q0-Q19
RCLK
t
ENH
t
ENS
12
t
WFF
D0-D39
REN
t
RCSLZ
t
A
t
DS
t
DH
t
ENS
t
ENH
t
A
12
t
DS
t
DS
t
DH
t
DH
t
CLK1
NO WRITE
NO WRITE
t
WFF
DATA READ NEXT DATA READ
Wx Wx+2 Wx+3
t
A
t
DS
t
DH
Wx+1
t
CLKH1
t
CLKH1
t
WFF
t
A
t
SKEW2(1)
t
WFF
t
ENS
t
RCSHZ
DATA
READ
NEXT DATA
READ
5995 drw20
t
SKEW2(1)
NOTES:
1. tSKEW2 is the minimum time between a falling RCLK edge and a rising WCLK edge to guarantee that FF will go HIGH (after one WCLK cycle plus tWFF). If the time between the falling edge of the RCLK and the rising edge of WCLK
is less than tSKEW2, then FF deassertion may be delayed one extra WCLK cycle.
2. OE = LOW, EF = HIGH.
3. WCS = LOW, RCS = LOW, WSDR = HIGH and RSDR = HIGH.
4. WCLK must be free running for FF to update.
39
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 18. Read Cycle and Read Chip Select (IDT Standard Mode)
NOTES:
1. tSKEW1 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that EF will go HIGH (after one RCLK cycle plus tREF). If the time between the
rising edge of WCLK and the rising edge of RCLK is less than tSKEW1, then EF deassertion may be delayed one extra RCLK cycle.
2. First data word latency = tSKEW1 + 1*TRCLK + tREF.
3. OE is LOW.
4. RCLK must be free running for EF to update.
RCLK
REN
12
5995 drw21
RCS
Q0 - Qn
WCLK
WEN
Dn
t
ENS
LAST DATA
D
x
t
ENS
t
ENS
t
ENS
EF
t
A
t
REF
t
REF
t
RCSLZ
LAST DATA-1
t
RCSHZ
t
RCSLZ
t
A
t
RCSHZ
t
SKEW1
(1)
t
ENH
t
ENS
t
DH
t
DS
t
ENH
40
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 19. Write Timing (FWFT Mode)
NOTES:
1. tSKEW1 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that OR will go LOW after two RCLK cycles plus tREF. If the time between the rising edge of WCLK and the rising edge of RCLK
is less than tSKEW1, then OR assertion may be delayed one extra RCLK cycle.
2. tSKEW2 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that PAE will go HIGH after one RCLK cycle plus tPAES. If the time between the rising edge of WCLK and the rising edge of RCLK
is less than tSKEW2, then the PAE deassertion may be delayed one extra RCLK cycle.
3. OE = LOW
4. n = PAE offset, m = PAF offset and D = maximum FIFO depth.
5. D = 16,385 for IDT72T4088, 32,769 for IDT72T4098, 65,537 for IDT72T40108, 131,073 for IDT72T40118.
6. First data word latency = tSKEW1 + 2*TRCLK + tREF.
W
1
W
2
W
4
W
[n +2]
W
[D-m-1]
W
[D-m-2]
W
[D-1]
W
D
W
[n+3]
W
[n+4]
W
[D-m]
W
[D-m+1]
WCLK
WEN
D0 - Dn
RCLK
t
DH
t
DS
t
SKEW1
(1)
REN
Q0 - Qn
PAF
PAE
IR
t
DS
t
DS
t
DS
t
SKEW2
t
A
t
REF
OR
t
PAES
t
PAFS
t
WFF
W
[D-m+2]
W
1
t
ENH
5995 drw22
PREVIOUS DATA IN OUTPUT REGISTER
(2)
W
3
123
1
D-1
2+1
][
W
D-1
+2
][
W
2
D-1
+3
][
W
2
12
t
ENS
RCS
t
RCSLZ
t
ENS
41
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 20. Read Timing (FWFT Mode)
NOTES:
1. tSKEW1 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that OR will go LOW after two RCLK cycles plus tREF. If the time between the rising edge of WCLK and the rising edge of RCLK
is less than tSKEW1, then OR assertion may be delayed one extra RCLK cycle.
2. tSKEW2 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that PAE will go HIGH after one RCLK cycle plus tPAES. If the time between the rising edge of WCLK and the rising edge of RCLK
is less than tSKEW2, then the PAE deassertion may be delayed one extra RCLK cycle.
3. OE = LOW
4. n = PAE offset, m = PAF offset and D = maximum FIFO depth.
5. D = 16,385 for IDT72T4088, 32,769 for IDT72T4098, 65,537 for IDT72T40108, 131,073 for IDT72T40118.
6. First data word latency = tSKEW1 + 2*TRCLK + tREF.
WCLK 12
WEN
D0 - Dn
RCLK
t
ENS
REN
Q0 - Qn
PAF
PAE
IR
OR
W
1
W
1
W
2
W
3
W
m+2
W
[m+3]
t
OHZ
t
SKEW1
t
ENH
t
DS
t
DH
t
OE
t
A
t
A
t
A
t
PAFS
t
WFF
t
WFF
t
ENS
OE
t
SKEW2
W
D
5995 drw23
t
PAES
W
[D-n]
W
[D-n-1]
t
A
t
A
t
REF
W
[D-1]
W
D
t
A
W
[D-n+1]
W
[m+4]
W
[D-n+2]
(1) (2)
t
ENS
D-1 + 1
][
W
2D-1 + 2
][
W
2
1
42
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 21. Read Cycle and Read Chip Select Timing (FWFT Mode)
NOTES:
1. tSKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that IR will go LOW after one WCLK cycle plus tWFF. If the time between the rising edge of RCLK and the rising edge of WCLK is
less than tSKEW1, then the IR assertion may be delayed one extra WCLK cycle.
2. tSKEW2 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that PAF will go HIGH after one WCLK cycle plus tPAFS. If the time between the rising edge of RCLK and the rising edge of WCLK
is less than tSKEW2, then the PAF deassertion may be delayed one extra WCLK cycle.
3. n = PAE Offset, m = PAF offset and D = maximum FIFO depth.
4. D = 16,385 for IDT72T4088, 32,769 for IDT72T4098, 65,537 for IDT72T40108, 131,073 for IDT72T40118.
5. OE = LOW.
6. RCLK must be free running for EF to update.
WCLK
12
WEN
D0 - Dn
RCLK
REN
Q0 - Qn
PAF
PAE
IR
OR
W
1
W
2
W
3
W
m+2
W
[m+3]
t
RCSHZ
t
SKEW1
t
ENH
t
DS
t
DH
t
A
t
A
t
PAFS
t
WFF
t
WFF
t
ENS
RCS
t
SKEW2
W
D
5995 drw24
t
PAES
W
[D-n]
W
[D-n-1]
t
A
t
A
W
[D-1]
W
D
t
A
W
[D-n+1]
W
[m+4]
W
[D-n+2]
(1) (2)
t
ENS
1
t
ENS
t
RCSLZ
t
ENS
t
REF
D-1
+ 1
][
W
2
D-1
+ 2
][
W
2
t
ENH
43
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 22 .
RCSRCS
RCSRCS
RCS
and
RENREN
RENREN
REN
Read Operation (FWFT Mode)
NOTES:
1. It is very important that the REN be held HIGH for at least one cycle after RCS has gone LOW. If REN goes LOW on the same cycle as RCS or earlier, then Word, W1 will be lost, Word, W2 will be read on the output when the
bus goes to LOW-Z.
2. The 1st Word will fall through to the output register regardless of REN and RCS. However, subsequent reads require that both REN and RCS be active, LOW.
3. RCS functions similarly to OE, when RCS is HIGH the read pointer will not increment.
WCLK
RCLK
REN
Qn
12
WEN
3
t
ENS
t
ENH
t
ENS
t
ENS
t
ENS
t
ENH
t
ENS
t
REF
t
REF
RCS
OR
t
RCSLZ
W1 W2
t
RCSHZ
t
RCSLZ
t
A
W2
t
SKEW
t
ENS
t
ENH
W2
Dn
t
DH
t
DS
t
DH
t
DS
W1
1st Word falls through to
O/P register on this cycle
5995 drw25
HIGH-Z
44
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 23 . Retransmit from MARK in Double Data Rate Mode (IDT Standard Mode)
NOTES:
1. Retransmit setup is complete when EF returns HIGH.
2. OE = LOW;RCS = LOW.
3. RT must be HIGH when reading from FIFO.
4. Once MARK is set, the write pointer will not increment past the ‘marked’ location, preventing overwrites of Retransmit data.
5. Before a “MARK” can be set there must be at least 160 bytes of data between the Write Pointer and Read Pointer locations. (160 bytes = 16 words = 8 long words).
6. RCLK must be free running for EF to update.
7. A transition in the PAE flag may not occur until one RCLK cycle later than shown.
8. In DDR mode the MARK function will “MARK” words only on even word boundaries (i.e. Rising edge of RCLK).
Q
0-
Qn
WCLK
RCLK
REN
PAF
t
CLKL2
t
CLKH2
t
CLK2
t
A
WMK
MARK
t
A
t
A
t
A
WMK+2
t
A
t
A
WMK+3 WMK+4 WMK+5 WMK+6 WMK+n
RT
EF
PAE
t
ENS
t
ENH
t
REF
t
REF
t
ENS
12
t
A
t
PAES
(7)
t
A
t
A
t
A
WMK WMK+1 WMK+2
t
SKEW2
12
t
PAFS
5995 drw26
t
ENH
t
ENS
t
ENS
WMK+1
45
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 24. Retransmit from Mark (FWFT Mode)
NOTES:
1. Retransmit setup is complete when OR returns LOW.
2. OE = LOW;RCS = LOW.
3. RT must be HIGH when reading from FIFO.
4. Once MARK is set, the write pointer will not increment past the ‘marked’ location, preventing overwrites of Retransmit data.
5. Before a “MARK” can be set there must be at least 160 bytes of data between the Write Pointer and Read Pointer locations. (160 bytes = 16 words = 8 long words).
6. RCLK must be free running for EF to update.
7. A transition in the PAE flag may not occur until one RCLK cycle later than shown.
t
REF
t
ENS
t
ENH
5995 drw27
t
ENS
W
MK-1
WCLK
RCLK
REN
RT
OR
PAF
PAE
Q
n
12
1
t
PAFS
t
REF
2
WEN
t
ENS
t
A
t
ENS
W
MK
W
MK+1
t
A
t
A
W
MK+n
t
A
W
MK+1
W
MK+2
t
A
t
ENS
MARK
t
ENH
t
ENS
t
PAES
(7)
t
A
t
SKEW2
W
MK
t
A
46
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 25. Loading of Programmable Flag Registers (IDT Standard and FWFT Modes)
NOTE:
1 . In SDR mode, X = 14 for the IDT72T4088, X = 15 for the IDT72T4098, X = 16 for the IDT72T40108, X = 17 for the IDT72T40118.
2 . In DDR mode, X = 13 for the IDT72T4088, X = 14 for the IDT72T4098, X = 15 for the IDT72T70108, X = 16 for the IDT72T40118.
SCLK
SEN
SI
5995 drw28
EMPTY OFFSET
FULL OFFSET
BIT X
(1)
tSENS
tSDS
tSENH
BIT X
(1)
BIT 1
tENH
tSDH
tSCLK
tSCKH tSCKL
BIT 1
Figure 26. Reading of Programmable Flag Registers (IDT Standard and FWFT Modes)
NOTE:
1 . In SDR mode, X = 14 for the IDT72T4088, X = 15 for the IDT72T4098, X = 16 for the IDT72T40108, X = 17 for the IDT72T40118.
2 . In DDR mode, X = 13 for the IDT72T4088, X = 14 for the IDT72T4098, X = 15 for the IDT72T40108, X = 16 for the IDT72T40118.
3. Offset register values are always read starting from the first location in the offset register upon initiating SREN.
SCLK
SREN
SO
5995 drw29
BIT 0
EMPTY OFFSET
FULL OFFSET
BIT X
(1)
t
SENS
t
SOA
t
SENH
BIT X
(1)
t
ENH
t
SOA
t
SCLK
t
SCKH
t
SCKL
BIT 0
47
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 27. Echo Read Clock & Read Enable Operation in Double Data Rate Mode (IDT Standard Mode Only)
NOTES:
1. The EREN output is “or gated” to RCS and REN and will follow these inputs provided that the FIFO is not empty. If the FIFO is empty, EREN will go HIGH to indicate that there is no new word available.
2. The EREN output is synchronous to RCLK.
3. OE = LOW.
4. The truth table for EREN is shown below:
RCLK
REN
EREN
ERCLK
EF
RCS
t
ENS
t
REF
t
ERCLK
t
ENH
Qn
t
ENS
t
ENH
t
CLKEN
t
CLKEN
t
CLKEN
t
CLKEN
t
OLZ
t
A
t
A
t
CLKEN
t
A
t
OLZ
t
OLZ
t
A
t
A
t
A
t
A
t
A
WD-10 WD-9 WD-8 WD-6 WD-5 WD-4 WD-3 WD-2 Last Word WD
5995 drw30
t
CLKEN
t
A
WD-7 WD-6
t
A
WD-1
t
ENS
NO Read NO Read
RCLK EF RCS REN EREN
↑1000
↑1011
↑1101
↑1111
↑0XX1
48
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
Figure 28. Echo RCLK and Echo
RENREN
RENREN
REN
Operation (FWFT Mode Only)
NOTE:
1. The O/P Register is the internal output register. Its contents are available on the Qn output bus only when RCS and OE are both active, LOW, that is the bus is not in High-
Impedance state.
2. OE is LOW.
Cycle:
a&b. At this point the FIFO is empty, OR is HIGH.
RCS and REN are both disabled, the output bus is High-Impedance.
c. Word Wn+1 falls through to the output register, OR goes active, LOW.
RCS is HIGH, therefore the Qn outputs are High-Impedance. EREN goes LOW to indicate that a new word has been placed on the output register.
d. EREN goes HIGH, no new word has been placed on the output register on this cycle.
e. No Operation.
f. RCS is LOW on this cycle, therefore the Qn outputs go to Low-Impedance and the contents of the output register (Wn+1) are made available.
NOTE: In FWFT mode is important to take RCS active LOW at least one cycle ahead of REN, this ensures the word (Wn+1) currently in the output register is made
available for at least one cycle.
g. REN goes active LOW, this reads out the second word, Wn+2.
EREN goes active LOW to indicate a new word has been placed into the output register.
h. Word Wn+3 is read out, EREN remains active, LOW indicating a new word has been read out.
NOTE: Wn+3 is the last word in the FIFO.
i. This is the next enabled read after the last word, Wn+3 has been read out. OR flag goes HIGH and EREN goes HIGH to indicate that there is no new word available.
3. OE is LOW.
4. The truth table for EREN is shown below:
Qn
O/P
Reg.
t
A
t
REF
OR
5995 drw31
t
RCSLZ
REN t
ENS
t
ENH
RCS
t
ENS
RCLK
abcdefghi
W
n+1
WCLK
WEN
D0 - Dn
t
SKEW1
t
ENS
t
DS
t
ENH
W
n+2
W
n+3
ERCLK
EREN
t
CLKEN
t
CLKEN
t
CLKEN
t
CLKEN
W
n+1
W
n+2
W
n+3
t
A
t
REF
W
n+1
W
n+2
W
n+3
t
A
W
n
Last Word
t
A
t
A
t
DH
t
DH
t
DH
t
DS
t
DS
12
t
ERCLK
HIGH-Z
RCLK OR RCS REN EREN
↑0000
↑0011
↑0101
↑0111
↑1XX1
49
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
NOTES:
1. m = PAF offset.
2. D = maximum FIFO Depth.
In IDT Standard Mode:
D=16,384 for the IDT72T4088, 32,768 for the IDT72T4098, 65,536 for the IDT72T40108, 131,072 for the IDT72T40118.
In FWFT Mode: D=16,385 for the IDT72T4088, 32,769 for the IDT72T4098, 65,537 for the IDT72T40108, 131,073 for the IDT72T40118.
3. PAF is asserted and updated on the rising edge of WCLK only.
4. tSKEW3 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that PAF will go HIGH (after one WCLK cycle plus tPAFS). If the time between the
rising edge of RCLK and the rising edge of WCLK is less than tSKEW3, then the PAF deassertion time may be delayed one extra WCLK cycle.
5. RCS = LOW.
Figure 29. Programmable Almost-Full Flag Timing (IDT Standard and FWFT Modes)
NOTES:
1 . n = PAE offset.
2. For IDT Standard Mode.
3. For FWFT Mode.
4. PAE is asserted and updated on the rising edge of RCLK only.
5.
tSKEW3 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that PAE will go HIGH (after one RCLK cycle plus tPAES). If the time between the
rising edge of WCLK and the rising edge of RCLK is less than tSKEW3, then the PAE deassertion may be delayed one extra RCLK cycle.
5. PAE is asserted and updated on the rising edge of RCLK only.
6. RCS = LOW.
Figure 30. Programmable Almost-Empty Flag Timing (IDT Standard and FWFT Modes)
WCLK
WEN
PAF
RCLK
REN 5995 drw32
1212
D-(m+1) words
in FIFO(2)
D - m words in FIFO(2)
D - (m +1) words in FIFO(2)
t
ENH
t
ENS
t
PAFS
t
ENS
t
ENH
t
CLKL1
t
SKEW3
(3)
t
PAFS
t
CLKH1
WCLK
WEN
PAE
RCLK
12 12
REN 5995 drw33
n + 1 words in FIFO
(2)
,
n + 2 words in FIFO
(3)
t
ENS
t
SKEW3
(4)
t
ENH
t
PAES
n words in FIFO
(2)
,
n + 1 words in FIFO
(3)
t
PAES
n words in FIFO
(2)
,
n + 1 words in FIFO
(3)
t
ENS
t
ENH
t
CLKH1
t
CLKL1
50
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
OPTIONAL CONFIGURATIONS
WIDTH EXPANSION CONFIGURATION
Word width may be increased simply by connecting together the control
signals of multiple devices. Status flags can be detected from any one device.
The exceptions are the EF and FF functions in IDT Standard mode and the IR
and OR functions in FWFT mode. Because of variations in skew between RCLK
and WCLK, it is possible for EF/FF deassertion and IR/OR assertion to vary
by one cycle between FIFOs. In IDT Standard mode, such problems can be
avoided by creating composite flags, that is, ANDing EF of every FIFO, and
separately ANDing FF of every FIFO. In FWFT mode, composite flags can
be created by ORing OR of every FIFO, and separately ORing IR of every
FIFO.
Figure 31 demonstrates a width expansion using two IDT72T4088/
72T4098/72T40108/72T40118 devices. D0 - D40 from each device form a 80-
bit wide input bus and Q0-Q39 from each device form a 80-bit wide output bus.
Any word width can be attained by adding additional IDT72T4088/72T4098/
72T40108/72T40118 devices.
NOTES:
1. Use an AND gate in IDT Standard mode, an OR gate in FWFT mode.
2. Do not connect any output control signals directly together.
3. FIFO #1 and FIFO #2 must be the same depth, but may be different word widths.
Figure 31. Block Diagram of 16,384 x 80, 32,768 x 80, 65,536 x 80, 131,072 x 80 Width Expansion
WRITE CLOCK (WCLK)
m + n
mn
MASTER RESET (MRS)
READ CLOCK (RCLK)
DATA OUT
n
m + n
WRITE ENABLE (WEN)
FULL FLAG/INPUT READY (FF/IR)
PROGRAMMABLE (PAF)
PROGRAMMABLE (PAE)
EMPTY FLAG/OUTPUT READY (EF/OR) #2
OUTPUT ENABLE (OE)
READ ENABLE (REN)
m
IDT
72T4088
72T4098
72T40108
72T40118
EMPTY FLAG/OUTPUT READY (EF/OR) #1
PARTIAL RESET (PRS)
5995 drw34
FULL FLAG/INPUT READY (FF/IR) #2
FIRST WORD FALL THROUGH
(FWFT)
RETRANSMIT (RT)
#1
FIFO
#2
GATE
(1)
GATE
(1)
D0 - Dm
DATA IN
Dm+1 - Dn
Q
0
- Qm
Qm+1
- Q
n
FIFO
#1
IDT
72T4088
72T4098
72T40108
72T40118
READ CHIP SELECT (RCS)
SERIAL CLOCK (SCLK)
51
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72T4088/98/108/118 2.5V HIGH-SPEED TeraSync™ DDR/SDR FIFO 40-BIT
CONFIGURATION 16,384 x 40, 32,768 x 40, 65,536 x 40 and 131,072 x 40
FEBRUARY 13, 2009
DEPTH EXPANSION CONFIGURATION IN SINGLE DATA RATE
(FWFT MODE ONLY)
The IDT72T4088 can easily be adapted to applications requiring depths
greater than 16,384, 32,768 for the IDT72T4098, 65,536 for the IDT72T40108,
131,072 for the IDT72T40118 with an 40-bit bus width. In FWFT mode, the
FIFOs can be connected in series (the data outputs of one FIFO connected to
the data inputs of the next) with no external logic necessary. The resulting
configuration provides a total depth equivalent to the sum of the depths
associated with each single FIFO. Figure 32 shows a depth expansion using
two IDT72T4088/72T4098/72T40108/72T40118 devices.
Care should be taken to select FWFT mode during Master Reset for all FIFOs
in the depth expansion configuration. Also, the devices must be operating in
Single Data Rate mode since that is the only mode available in FWFT. The first
word written to an empty configuration will pass from one FIFO to the next ("ripple
down") until it finally appears at the outputs of the last FIFO in the chain – no read
operation is necessary but the RCLK of each FIFO must be free-running. Each
time the data word appears at the outputs of one FIFO, that device's OR line goes
LOW, enabling a write to the next FIFO in line.
For an empty expansion configuration, the amount of time it takes for OR of
the last FIFO in the chain to go LOW (i.e. valid data to appear on the last FIFO's
outputs) after a word has been written to the first FIFO is the sum of the delays
for each individual FIFO:
(N – 1)*(4*transfer clock) + 3*TRCLK
where N is the number of FIFOs in the expansion and TRCLK is the RCLK period.
Note that extra cycles should be added for the possibility that the tSKEW1
specification is not met between WCLK and transfer clock, or RCLK and transfer
clock, for the OR flag.
The "ripple down" delay is only noticeable for the first word written to an empty
depth expansion configuration. There will be no delay evident for subsequent
words written to the configuration.
The first free location created by reading from a full depth expansion
configuration will "bubble up" from the last FIFO to the previous one until it finally
moves into the first FIFO of the chain. Each time a free location is created in one
FIFO of the chain, that FIFO's IR line goes LOW, enabling the preceding FIFO
to write a word to fill it.
For a full expansion configuration, the amount of time it takes for IR of the first
FIFO in the chain to go LOW after a word has been read from the last FIFO is
the sum of the delays for each individual FIFO:
(N – 1)*(3*transfer clock) + 2 TWCLK
where N is the number of FIFOs in the expansion and TWCLK is the WCLK
period. Note that extra cycles should be added for the possibility that the tSKEW1
specification is not met between RCLK and transfer clock, or WCLK and transfer
clock, for the IR flag.
The Transfer Clock line should be tied to either WCLK or RCLK, whichever
is faster. Both these actions result in data moving, as quickly as possible, to the
end of the chain and free locations to the beginning of the chain.
Figure 32. Block Diagram of 32,768 x 40, 65,536 x 40, 131,072 x 40, 262,144 x 40 Depth Expansion in Single Data Rate Mode
Dn
INPUT READY
WRITE ENABLE
WRITE CLOCK
WEN
WCLK
IR
DATA IN
RCLK READ CLOCK
RCLK
REN
OE OUTPUT ENABLE
OUTPUT READY
Qn
Dn
IR
GND
WEN
WCLK
OR
REN
OE
Qn
READ ENABLE
OR
DATA OUT
TRANSFER CLOCK
5995 drw35
n
n n
FWFT FWFT
FWFT
IDT
72T4088
72T4098
72T40108
72T40118
RCS READ CHIP SELECT
RCS
IDT
72T4088
72T4098
72T40108
72T40118
CORPORATE HEADQUARTERS for SALES: for Tech Support:
6024 Silver Creek Valley Road 800-345-7015 or 408-284-8200 408-360-1753
San Jose, CA 95138 fax: 408-284-2775 email: FIFOhelp@idt.com
www.idt.com
52
ORDERING INFORMATION
Plastic Ball Grid Array (PBGA, BB208-1)
Low Power
5995 drw36
Commercial Only
Commercial Only
Commercial and Industrial
Commercial Only
4
5
6-7
10
72T4088 16,384 x 40 ⎯ 2.5V High-Speed TeraSync
TM
DDR/SDR FIFO
72T4098 32,768 x 40 ⎯ 2.5V High-Speed TeraSync
TM
DDR/SDR FIFO
72T40108 65,536 x 40 ⎯ 2.5V High-Speed TeraSync
TM
DDR/SDR FIFO
72T40118 131,072 x 40 ⎯ 2.5V High-Speed TeraSync
TM
DDR/SDR FIFO
Clock Cycle Time (t
CLK
)
Speed in Nanoseconds
BB
L
Commercial (0°C to +70°C)
Industrial (-40°C to +85°C)
XXXXX
Device Type
X
Power
XX
Speed
X
Package
X
Process /
Temperature
Range
BLANK
I
(1)
Green
G
X
NOTES:
1. Industrial temperature range product is available for 6-7ns as a standard product. All other speed grades are available by special order.
2. Green parts are available. For specific speeds and packages contact your sales office.
DATASHEET DOCUMENT HISTORY
03/01/2002 pgs. 1, 4, 6, 8, 9, and 23.
04/08/2002 pgs. 1, 8, 9, 11, 33-37, 42, 46-48, and 51.
04/24/2002 pgs. 19, and 28.
05/24/2002 pgs. 6-9, and 12.
11/21/2002 pgs. 1, and 10.
02/11/2003 pgs. 7, 8, and 27.
03/20/2003 pgs. 25, 27, 28, and 44.
12/17/2003 pgs. 10, 31-34, 36-38, 44, and 49.
09/21/2004 pgs. 1, 3, 9-11, 17, and 28.
02/13/2009 pgs. 1 and 52.
