1 of 18 REV: 042506
FEATURES
Integrated NV SRAM, Real-Time Clock,
Crystal, Power-Fail Control Circuit, and
Lithium Energy Source
Clock Registers are Accessed Identically to
the Static RAM. These Registers are Resident
in the Eight Top RAM Locations.
Century Byte Register (i.e., Y2K Compliant)
Totally Nonvolatile with Over 10 Years of
Operation in the Absence of Power
BCD-Coded Century, Year, Month, Date,
Day, Hours, Minutes, and Seconds with
Automatic Leap-Year Compensation Valid
Up to the Year 2100
Battery Voltage-Level Indicator Flag
Power-Fail Write Protection Allows for ±10%
VCC Power-Supply Tolerance
Lithium Energy Source is Electrically
Disconnected to Retain Freshness Until
Power is Applied for the First Time
DIP Module Only
Standard JEDEC Byte-Wide 32k x 8 Static
RAM Pinout
PowerCap Module Board Only
Surface-Mountable Package for Direct
Connection to PowerCap Containing
Battery and Crystal
Replaceable Battery (PowerCap)
Power-On Reset Output
Pin-for-Pin Compatible with Other Densities
of DS174xP Timekeeping RAM
Also Available in Industrial Temperature
Range: -40°C to +85°C
UL Recognized
PIN CONFIGURATIONS
PowerCap is a registered trademark of Dallas Semiconductor.
DS1744/DS1744P
Y2K-Compliant, Nonvolatile Timekeeping R
A
Ms
www.maxim-ic.com
1
N.C.
2
3
N.C.
N.C.
R
S
T
VCC
WE
OE
CE
DQ7
DQ6
DQ5
DQ4
DQ3
DQ2
DQ1
DQ0
GND
4
5
6
7
8
9
10
11
12
13
14
15
16
17
N.C.
A
14
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
A
13
A
12
A
11
A
10
A
9
A
8
A
7
A
6
A
5
A
4
A
3
A
2
A
1
A
0
34 N.C.
X1 GND VBAT X2
PowerCap MODULE BOARD
(Uses DS9034PCX PowerCap)
DS1744P
TOP VIEW
VCC
W
E
A
13
A
8
A
9
A
11
O
E
A
10
C
E
DQ7
DQ6
DQ5
DQ4
DQ3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
A14
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
GND
28
27
26
25
24
23
22
21
20
19
18
17
16
15
DS1744
EDIP
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
2 of 20
PIN DESCRIPTION
PIN
EDIP PowerCap NAME FUNCTION
1 32 A14
2 30 A12
3 25 A7
4 24 A6
5 23 A5
6 22 A4
7 21 A3
8 20 A2
9 19 A1
10 18 A0
21 28 A10
23 29 A11
24 27 A9
25 26 A8
26 31 A13
Address Input
11 16 DQ0
12 15 DQ1
13 14 DQ2
15 13 DQ3
16 12 DQ4
17 11 DQ5
18 10 DQ6
19 9 DQ7
Data Input/Output
14 17 GND Ground
20 8 CE Active-Low Chip-Enable Input
22 7 OE Active-Low Output-Enable Input
27 6 WE Active-Low Write-Enable Input
28 5 VCC Power-Supply Input
— 4 RST Active-Low Reset Output, Open Drain. Requires a pullup resistor for
proper operation.
— 1, 2, 3, 33,
34 N.C. No Connection
— X1, X2,
VBAT Crystal Connections, VBAT Battery Connection
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
3 of 20
ORDERING INFORMATION
PART VOLTAGE
(V) TEMP RANGE PIN-PACKAGE TOP MARK**
DS1744-70 5.0 0°C to +70°C 28 EDIP DS1744-70
DS1744-70+ 5.0 0°C to +70°C 28 EDIP DS1744+70
DS1744-70IND 5.0 -40°C to +85°C 28 EDIP DS1744-70IND
DS1744-100+ 5.0 0°C to +70°C 28 EDIP DS1744+100
DS1744W-120 3.3 0°C to +70°C 28 EDIP DS1744W-120
DS1744W-120+ 3.3 0°C to +70°C 28 EDIP DS1744W+120
DS1744W-120IND 3.3 -40°C to +85°C 28 EDIP DS1744W-120IND
DS1744P-70 5.0 0°C to +70°C 34 PowerCap* DS1744P-70
DS1744P-70+ 5.0 0°C to +70°C 34 PowerCap* DS1744P+70
DS1744P-70IND 5.0 -40°C to +85°C 34 PowerCap* DS1744P-70IND
DS1744P-100+ 5.0 0°C to +70°C 34 PowerCap* DS1744P+100
DS1744WP-120 3.3 0°C to +70°C 34 PowerCap* DS1744WP-120
DS1744WP-120+ 3.3 0°C to +70°C 34 PowerCap* DS1744WP+120
DS1744WP-120IND 3.3 -40°C to +85°C 34 PowerCap* DS1744WP-120IND
+ Denotes a lead-free/RoHS-compliant device.
*DS9034-PCX, DS9034I-PCX, DS9034-PCX+ required (must be ordered separately).
** A “+” anywhere in the top mark denotes a lead-free device. An “IND” denotes an industrial temperature grade device.
DESCRIPTION
The DS1744 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) and 32k x 8
NV SRAM. User access to all registers within the DS1744 is accomplished with a byte-wide interface as
shown in Figure 1. The RTC information and control bits reside in the eight uppermost RAM locations.
The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour
BCD format. Corrections for the date of each month and leap year are made automatically. The RTC clock
registers are double-buffered to avoid access of incorrect data that can occur during clock update cycles.
The double-buffered system also prevents time loss as the timekeeping countdown continues unabated by
access to time register data. The DS1744 also contains its own power-fail circuitry that deselects the
device when the VCC supply is in an out-of-tolerance condition. This feature prevents loss of data from
unpredictable system operation brought on by low VCC as errant access and update cycles are avoided.
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
4 of 20
Figure 1. DS1744/DS1744P Block Diagram
PACKAGES
The DS1744 is available in two packages (28-pin encapsulated DIP and 34-pin PowerCap module). The
28-pin EDIP module integrates the crystal, lithium energy source, and silicon all in one package. The 34-
pin PowerCap module board is designed with contacts for connection to a separate PowerCap
(DS9034PCX) that contains the crystal and battery. This design allows the PowerCap to be mounted on
top of the DS1744P after the completion of the surface-mount process. Mounting the PowerCap after the
surface-mount process prevents damage to the crystal and battery due to the high temperatures required
for solder reflow. The PowerCap is keyed to prevent reverse insertion. The PowerCap module board and
PowerCap are ordered separately and shipped in separate containers. The part number for the PowerCap is
DS9034PCX.
CLOCK OPERATIONS—READING THE CLOCK
While the double-buffered register structure reduces the chance of reading incorrect data, internal updates
to the DS1744 clock registers should be halted before clock data is read to prevent reading of data in
transition. However, halting the internal clock register updating process does not affect clock accuracy.
Updating is halted when a 1 is written into the read bit, bit 6 of the century register (Table 2). As long as a
1 remains in that position, updating is halted. After a halt is issued, the registers reflect the count, that is,
day, date, and time that was current at the moment the halt command was issued. However, the internal
clock registers of the double-buffered system continue to update so that the clock accuracy is not affected
by the access of data. All the DS1744 registers are updated simultaneously after the internal clock-register
updating process has been re-enabled. Updating is within a second after the read bit is written to 0. The
READ bit must be a 0 for a minimal of 500µs to ensure the external registers are updated.
DS1744/DS1744P
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
5 of 20
Table 1. Truth Table
VCC CE OE WE MODE DQ POWER
VIH X X Deselect High-Z Standby
VIL X VIL Write Data In Active
VIL V
IL V
IH Read Data Out Active
VCC > VPF
VIL V
IH V
IH Read High-Z Active
VSO < VCC < VPF X X X Deselect High-Z CMOS Standby
VCC < VSO < VPF X X X Deselect High-Z Data-Retention Mode
SETTING THE CLOCK
As shown in Table 2, bit 7 of the century register is the write bit. Setting the write bit to a 1, like the read
bit, halts updates to the DS1744 registers. The user can then load them with the correct day, date, and time
data in 24-hour BCD format. Resetting the write bit to a 0 then transfers those values to the actual clock
counters and allows normal operation to resume.
STOPPING AND STARTING THE CLOCK OSCILLATOR
The clock oscillator can be stopped at any time. To increase the shelf life, the oscillator can be turned off
to minimize current drain from the battery. The OSC bit is the MSB (bit 7) of the seconds registers (Table
2). Setting it to a 1 stops the oscillator.
FREQUENCY TEST BIT
As shown in Table 2, bit 6 of the day byte is the frequency test bit. When the frequency test bit is set to
logic 1 and the oscillator is running, the LSB of the seconds register toggles at 512Hz. When the seconds
register is being read, the DQ0 line toggles at the 512Hz frequency as long as conditions for access remain
valid (i.e., CE low, OE low, WE high, and address for seconds register remain valid and stable).
CLOCK ACCURACY (DIP MODULE)
The DS1744 is guaranteed to keep time accuracy to within ±1 minute per month at +25°C. The RTC is
calibrated at the factory by Dallas Semiconductor using nonvolatile tuning elements, and does not require
additional calibration. For this reason, methods of field clock calibration are not available and not
necessary. Clock accuracy is also affected by the electrical environment; caution should be taken to place
the RTC in the lowest-level EMI section of the PC board layout. For additional information, refer to
Application Note 58: Crystal Considerations with Dallas Real-Time Clocks.
CLOCK ACCURACY (PowerCap MODULE)
The DS1744 and DS9034PCX are individually tested for accuracy. Once mounted together, the module
typically keeps time accuracy to within ±1.53 minutes per month (35ppm) at +25°C. Clock accuracy is
also affected by the electrical environment and caution should be taken to place the RTC in the lowest-
level EMI section of the PC board layout. For additional information, refer to Application Note 58: Crystal
Considerations with Dallas Real-Time Clocks.
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
6 of 20
Table 2. Register Map
DATA
ADDRESS B7 B6 B5 B4 B3 B2 B1 B0
FUNCTION RANGE
7FFF 10 Year Year Year 00-99
7FFE X X X 10
Month Month Month 01-12
7FFD X X 10 Date Date Date 01-31
7FFC BF FT X X X Day Day 01-07
7FFB X X 10 Hour Hour Hour 00-23
7FFA X 10 Minutes Minutes Minutes 00-59
7FF9 OSC 10 Seconds Seconds Seconds 00-59
7FF8 W R 10 Century Century Century 00-39
OSC = Stop Bit R = Read Bit FT = Frequency Test
W = Write Bit X = See Note BF = Battery Flag
Note: All indicated “X” bits are not used but must be set to a “0” during write cycle to ensure proper
clock operation.
RETRIEVING DATA FROM RAM OR CLOCK
The DS1744 is in the read mode whenever OE (output enable) is low, WE (write enable) is high, and
CE (chip enable) is low. The device architecture allows ripple-through access to any of the address
locations in the NV SRAM. Valid data is available at the DQ pins within tAA after the last address input is
stable, providing that the CE and OE access times and states are satisfied. If CE or OE access times and
states are not met, valid data is available at the latter of chip-enable access (tCEA) or at output-enable access
time (tOEA). The state of the DQ pins is controlled by CE and OE . If the outputs are activated before tAA,
the data lines are driven to an intermediate state until tAA. If the address inputs are changed while CE and
OE remain valid, output data remains valid for output-data hold time (tOH) but then goes indeterminate
until the next address access.
WRITING DATA TO RAM OR CLOCK
The DS1744 is in the write mode whenever WE and CE are in their active state. The start of a write is
referenced to the latter occurring transition of WE or CE . The addresses must be held valid throughout
the cycle. CE or WE must return inactive for a minimum of tWR prior to the initiation of another read or
write cycle. Data in must be valid tDS prior to the end of write and remain valid for tDH afterward. In a
typical application, the OE signal is high during a write cycle. However, OE can be active provided that
care is taken with the data bus to avoid bus contention. If OE is low prior to WE transitioning low, the
data bus can become active with read data defined by the address inputs. A low transition on WE then
disables the output tWEZ after WE goes active.
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
7 of 20
DATA-RETENTION MODE
The 5V device is fully accessible and data can be written or read only when VCC is greater than V
PF.
However, when VCC is below the power-fail point, VPF (point at which write protection occurs), the
internal clock registers and SRAM are blocked from any access. At this time the power-fail reset-output
signal ( RST ) is driven active and remains active until VCC returns to nominal levels. When VCC falls
below the battery switch point VSO (battery supply level), device power is switched from the VCC pin to the
backup battery. RTC operation and SRAM data are maintained from the battery until VCC is returned to
nominal levels. The 3.3V device is fully accessible, and data can be written or read only when VCC is
greater than VPF. When VCC falls below VPF access to the device is inhibited. At this time the power-fail
reset-output signal ( RST ) is driven active and remains active until VCC returns to nominal levels. If VPF is
less than VSO, the device power is switched from VCC to the backup supply (VBAT) when VCC drops below
VPF. If VPF is greater than VSO, the device power is switched from VCC to the backup supply (VBAT) when
VCC drops below VSO. RTC operation and SRAM data are maintained from the battery until VCC is
returned to nominal levels. The RST signal is an open-drain output and requires a pullup. Except for the
RST , all control, data, and address signals must be powered down when VCC is powered down.
BATTERY LONGEVITY
The DS1744 has a lithium power source that is designed to provide energy for clock activity and clock and
RAM data retention when the VCC supply is not present. The capability of this internal power supply is
sufficient to power the DS1744 continuously for the life of the equipment in which it is installed. For
specification purposes, the life expectancy is 10 years at +25°C with the internal clock oscillator running
in the absence of VCC power. Each DS1744 is shipped from Dallas Semiconductor with its lithium energy
source disconnected, guaranteeing full energy capacity. When VCC is first applied at a level greater than
VPF, the lithium energy source is enabled for battery-backup operation. Actual life expectancy of the
DS1744 is much longer than 10 years since no lithium battery energy is consumed when VCC is present.
BATTERY MONITOR
The DS1744 constantly monitors the battery voltage of the internal battery. The battery flag bit (bit 7) of
the day register is used to indicate the voltage-level range of the battery. This bit is not writable and should
always be a 1 when read. If a 0 is ever present, an exhausted lithium energy source is indicated, and both
the contents of the RTC and RAM are questionable.
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
8 of 20
ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground……………………..…….…..……………..-0.3V to +6.0V
Operating Temperature Range………………...…………………………..-40°C to +85°C (noncondensing)
Storage Temperature Range……………………………………………….-40°C to +85°C (noncondensing)
Soldering Temperature………………………….See IPC/JEDEC J-STD-020 Specification (EDIP, Note 7)
This is a stress rating only and functional operation of the device at these or any other condition beyond those indicated in the operation
sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time can affect
reliability.
OPERATING RANGE
RANGE TEMP RANGE VCC
Commercial 0°C to +70°C, Noncondensing 3.3V ±10% or 5V±10%
Industrial -40°C to +85°C, Noncondesnsing 3.3V ±10% or 5V±10%
RECOMMENDED DC OPERATING CONDITIONS
(TA = Over the operating range)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
VIH 2.2 VCC + 0.3V V 1
Logic 1 Voltage (All Inputs)
VCC = 5V ±10%
VCC = 3.3V ±10% VIH 2.0 VCC + 0.3V V
VIL -0.3 0.8 V
Logic 0 Voltage (All Inputs)
VCC = 5V ±10%
VCC = 3.3V ±10% VIL 0.3 0.6 V 1
DC ELECTRICAL CHARACTERISTICS
(VCC = 5.0V ±10%, TA = Over the operating range.)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Active Supply Current ICC 75 mA 2, 3
TTL Standby Current
(CE = VIH) ICC1 6 mA 2, 3
CMOS Standby Current
(CE ≥ VCC - 0.2V) Icc2 4 mA 2, 3
Input Leakage Current (Any
Input) IIL -1 +1
µA
Output Leakage Current
(Any Output) IOL -1 +1
µA
Output Logic 1 Voltage
(IOUT = -1.0mA) VOH 2.4 1
Output Logic 0 Voltage
(IOUT = +2.1mA) VOL 0.4 1
Write Protection Voltage VPF 4.25 4.50 V 1
Battery Switchover Voltage VSO V
BAT 1, 4
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
9 of 20
DC ELECTRICAL CHARACTERISTICS
(VCC = 3.3V ±10%, TA = Over the operating range.)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Active Supply Current ICC 30 mA 2, 3
TTL Standby Current
(CE = VIH) ICC1 2 mA 2, 3
CMOS Standby Current
(CE ≥ VCC - 0.2V) ICC2 2 mA 2, 3
Input Leakage Current (Any
Input) IIL -1 +1
µA
Output Leakage Current
(Any Output) IOL -1 +1
µA
Output Logic 1 Voltage
(IOUT = -1.0mA) VOH 2.4 1
Output Logic 0 Voltage
(IOUT = +2.1mA) VOL 0.4 1
Write Protection Voltage VPF 2.80 2.97 V 1
Battery Switchover Voltage VSO
VBAT
or
VPF
V 1, 4
AC CHARACTERISTICS—READ CYCLE (5V)
(VCC = 5.0V ±10%, TA = Over the operating range.)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Read Cycle Time tRC 70 ns
Address Access Time tAA 70 ns
CE to DQ Low-Z tCEL 5 ns
CE Access Time tCEA 70 ns
CE Data Off Time tCEZ 25 ns
OE to DQ Low-Z tOEL 5 ns
OE Access Time tOEA 35 ns
OE Data Off Time tOEZ 25 ns
Output Hold from Address tOH 5 ns
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
10 of 20
AC CHARACTERISTICS—READ CYCLE (3.3V)
(VCC = 3.3V ±10%, TA = Over the operating range.)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Read Cycle Time tRC 120 ns
Address Access Time tAA 120 ns
CE to DQ Low-Z tCEL 5 ns
CE Access Time tCEA 120 ns
CE Data Off Time tCEZ 40 ns
OE to DQ Low-Z tOEL 5 ns
OE Access Time tOEA 100 ns
OE Data Off Time tOEZ 35 ns
Output Hold from Address tOH 5 ns
READ CYCLE TIMING DIAGRAM
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
11 of 20
AC CHARACTERISTICS—WRITE CYCLE (5V)
(VCC = 5.0V ±10%, TA = Over the operating range.)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Write Cycle Time tWC 70 ns
Address Setup Time tAS 0 ns
WE Pulse Width tWEW 50 ns
CE Pulse Width tCEW 60 ns
Data Setup Time tDS 30 ns
Data Hold Time tDH1 0 ns 8
Data Hold Time tDH2 0 ns 9
Address Hold Time tAH1 5 ns 8
Address Hold Time tAH2 5 ns 9
WE Data Off Time tWEZ 25 ns
Write Recovery Time tWR 5 ns
AC CHARACTERISTICS—WRITE CYCLE (3.3V)
(VCC = 3.3V ±10%, TA = Over the operating range.)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Write Cycle Time tWC 120
ns
Address Setup Time tAS 0
120 ns
WE Pulse Width tWEW 100 ns
CE Pulse Width tCEW 110 ns
CE and CE2 Pulse Width tCEW 110 ns
Data Setup Time tDS 80
ns
Data Hold Time tDH1 0
ns 8
Data Hold Time tDH2 0
ns 9
Address Hold Time tAH1 0
ns 8
Address Hold Time tAH2 10
ns 9
WE Data Off Time tWEZ 40 ns
Write Recovery Time tWR 10
ns
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
12 of 20
WRITE CYCLE TIMING DIAGRAM, WRITE-ENABLE CONTROLLED
WRITE CYCLE TIMING DIAGRAM, CHIP-ENABLE CONTROLLED
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
13 of 20
POWER-UP/DOWN AC CHARACTERISTICS (5V)
(VCC = 5.0V ±10%, TA = Over the operating range.)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
CE or WE at VIH Before Power-Down tPD 0
µs
VCC Fall Time: VPF(MAX) to VPF(MIN) t
F 300
µs
VCC Fall Time: VPF(MIN) to VSO t
FB 10
µs
VCC Rise Time: VPF(MIN) to VPF(MAX) t
R 0
µs
Power-Up Recover Time tREC 35 ms
Expected Data-Retention Time
(Oscillator ON) tDR 10 years 5, 6
POWER-UP/DOWN TIMING (5V DEVICE)
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
14 of 20
POWER-UP/DOWN CHARACTERISTICS (3.3V)
(VCC = 3.3V ±10%, TA = Over the operating range.)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
CE or WE at VIH, Before Power-
Down tPD 0
µs
VCC Fall Time: VPF(MAX) to VPF(MIN) t
F 300
µs
VCC Rise Time: VPF(MIN) to VPF(MAX) t
R 0
µs
VPF to RST High tREC 35 ms
Expected Data-Retention Time
(Oscillator ON) tDR 10 years 5, 6
POWER-UP/DOWN WAVEFORM TIMING (3.3V DEVICE)
CAPACITANCE
(TA = +25°C)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Capacitance On All Input Pins CIN 14 pF
Capacitance On All Output Pins CO 10 pF
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
15 of 20
AC TEST CONDITIONS
Output Load: 50pF + 1TTL Gate
Input Pulse Levels: 0 to 3.0V
Timing Measurement Reference Levels:
Input: 1.5V
Output: 1.5V
Input Pulse Rise and Fall Times: 5ns
NOTES:
1) Voltages are referenced to ground.
2) Typical values are at +25°C and nominal supplies.
3) Outputs are open.
4) Battery switchover occurs at the lower of either the battery terminal voltage or VPF.
5) Data-retention time is at +25°C.
6) Each DS1744 has a built-in switch that disconnects the lithium source until the user first applies VCC.
The expected tDR is defined for DIP modules and assembled PowerCap modules as a cumulative time
in the absence of VCC starting from the time power is first applied by the user.
7) RTC modules (DIP) can be successfully processed through conventional wave-soldering techniques as
long as temperature exposure to the lithium energy source contained within does not exceed +85°C.
Post-solder cleaning with water-washing techniques is acceptable, provided that ultrasonic vibration is
not used.
In addition, for the PowerCap:
a. ) Dallas Semiconductor recommends that PowerCap module bases experience one pass through
solder reflow oriented with the label side up (“live-bug”).
b.) Hand soldering and touch-up: Do not touch or apply the soldering iron to leads for more than
3 seconds. To solder, apply flux to the pad, heat the lead frame pad, and apply solder. To
remove the part, apply flux, heat the lead frame pad until the solder reflows, and use a solder
wick to remove solder.
8) tAH1, tDH1 are measured from WE going high.
9) tAH2, tDH2 are measured from CE going high.
DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs
20 of 20
Maxim/Dallas Semiconductor cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim/Dallas Semiconductor product.
No circuit patent licenses are implied. Maxim/Dallas Semiconductor reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2006 Maxim Integrated Products • Printed USA
The Maxim logo is a registered trademark of Maxim Integrated Products, Inc. The Dallas logo is a registered trademark of Dallas Semiconductor Corporation.
PACKAGE INFORMATION (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For
the latest package outline information, go to www.maxim-ic.com/DallasPackInfo.)
ENGLISH • ???? • ??? • ???
WHAT'S NEW
PRODUCTS
SOLUTIONS
DESIGN
APPNOTES
SUPPORT
BUY
COMPANY
MEMBERS
DS1744
Part Number Table
Notes:
See the DS1744 QuickView Data Sheet for further information on this product family or download the DS1744 full data sheet
(PDF, 864kB).
1.
Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.2.
Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.3.
Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt. More: See full data sheet or Part
Naming Conventions.
4.
* Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses.5.
Part Number
Notes
Free
Sample
Buy
Direct
Package:
TYPE PINS SIZE
DRAWING CODE/VAR *
Temp
RoHS/Lead-Free?
Materials Analysis
DS1744-70
5V,
70ns
MOD;28 pin;600
Dwg: 56-G0002-001A (PDF)
Use pkgcode/variation: MDF28-3*
0C to +70C
RoHS/Lead-Free: No
Materials Analysis
DS1744W-120+
MOD;28 pin;600
Dwg: 56-G0002-001A (PDF)
Use pkgcode/variation: MDF28+3*
0C to +70C
RoHS/Lead-Free: Yes
Materials Analysis
DS1744-70+
MOD;28 pin;600
Dwg: 56-G0002-001A (PDF)
Use pkgcode/variation: MDF28+3*
0C to +70C
RoHS/Lead-Free: Yes
Materials Analysis
DS1744W-120
3.3V,
120ns
MOD;28 pin;600
Dwg: 56-G0002-001A (PDF)
Use pkgcode/variation: MDF28-3*
0C to +70C
RoHS/Lead-Free: No
Materials Analysis
DS1744W-120IND
MOD;28 pin;600
Dwg: 56-G0002-001A (PDF)
Use pkgcode/variation: MDF28-3*
-40C to +85C
RoHS/Lead-Free: No
Materials Analysis
DS1744-70IND+
MOD;28 pin;600
Dwg: 56-G0002-001A (PDF)
Use pkgcode/variation: MDF28+3*
-40C to +85C
RoHS/Lead-Free: Yes
Materials Analysis
DS1744-70IND
MOD;28 pin;600
Dwg: 56-G0002-001A (PDF)
Use pkgcode/variation: MDF28-3*
-40C to +85C
RoHS/Lead-Free: No
Materials Analysis
DS1744W-120IND+
MOD;28 pin;600
Dwg: 56-G0002-001A (PDF)
Use pkgcode/variation: MDF28+3*
-40C to +85C
RoHS/Lead-Free: Yes
Materials Analysis
DS1744WP-120
3.3V,
120ns
PWRCP;34 pin;960
Dwg: 56-G0003-001A1 (PDF)
Use pkgcode/variation: PC2-2*
0C to +70C
RoHS/Lead-Free: No
Materials Analysis
DS1744WP-120+
PWRCP;34 pin;960
Dwg: 56-G0003-001A1 (PDF)
Use pkgcode/variation: PC2+2*
0C to +70C
RoHS/Lead-Free: Yes
Materials Analysis
DS1744WP-120IND
PWRCP;34 pin;960
Dwg: 56-G0003-001A1 (PDF)
Use pkgcode/variation: PC2-2*
-40C to +85C
RoHS/Lead-Free: No
Materials Analysis
DS1744WP-120IND+
PWRCP;34 pin;960
Dwg: 56-G0003-001A1 (PDF)
Use pkgcode/variation: PC2+2*
-40C to +85C
RoHS/Lead-Free: Yes
Materials Analysis
Didn't Find What You Need?
CONTACT US: SEND US AN EMAIL
Copyright 2007 by Maxim Integrated Products, Dallas Semiconductor • Legal Notices • Privacy Policy
