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EOL Data Sheet
Multi-Purpose Flash Plus + PSRAM ComboMemory
SST32HF64A2
©2009 Silicon Storage Technology, Inc. S71299-04-EOL 3/09
The SST32HF64A2 device is suited for applications that
use both flash memory and PSRAM memory to store code
or data, and is ideal for systems requiring low power and
small form factor. The SST32HF64A2 significantly
improves performance and reliability, while lowering power
consumption, when compared with multiple chip solutions.
The total energy consumed is a function of the applied volt-
age, current, and time of application. Since for any given
voltage range, the SuperFlash technology uses less cur-
rent to program and has a shorter erase time, the total
energy consumed during any Erase or Program operation
is less than alternative flash technologies.
The SuperFlash technology provides fixed Erase and Pro-
gram times, independent of the number of Erase/Program
cycles that have occurred. Therefore the system software
or hardware does not have to be modified or de-rated as is
necessary with alternative flash technologies, whose Erase
and Program times increase with accumulated Erase/Pro-
gram cycles.
Device Operation
The SST32HF64A2 uses BES1#, BES2 and BEF# to con-
trol operation of either the flash or the PSRAM memory
bank. When BEF# is low, the flash bank is activated for
Read, Program or Erase operation. When BES1# is low
and BES2 is high, the PSRAM is activated for Read and
Write operation. BEF# and BES1# cannot be at low level,
and BES2 cannot be at high level at the same time. If all
bank enable signals are asserted, bus contention will
result and the device may suffer permanent damage.
All address, data, and control lines are shared by flash and
PSRAM memory banks which minimizes power consump-
tion and loading. The device goes into standby when BEF#
and BES1# bank enables are raised to VIHC (Logic High) or
when BEF# is high and BES2 is low.
Concurrent Read/Write Operation
The SST32HF64A2 provides the unique benefit of being
able to read from or write to PSRAM, while simultaneously
erasing or programming the flash. This allows data alter-
ation code to be executed from PSRAM, while altering the
data in flash. See Figure 29 for a flowchart. The following
table lists all valid states.
The device will ignore all SDP commands when an Erase
or Program operation is in progress. Note that Product
Identification commands use SDP; therefore, these com-
mands will also be ignored while an Erase or Program
operation is in progress.
Flash Read Operation
The Read operation of the SST32HF64A2 is controlled by
BEF# and OE#. Both have to be low, with WE# high, for the
system to obtain data from the outputs. BEF# is used for
flash memory bank selection. When BEF# is high, the chip
is deselected and only standby power is consumed. OE# is
the output control and is used to gate data from the output
pins. The data bus is in high impedance state when OE# is
high. Refer to Figure 7 for further details.
Flash Word-Program Operation
The flash memory bank of the SST32HF64A2 is pro-
grammed on a word-by-word basis. Before Program opera-
tions, the memory must be erased first. The Program
operation consists of three steps.
1. Load the three-byte sequence for Software Data
Protection.
2. Load word address and word data. During the
Word-Program operation, the addresses are
latched on the falling edge of either BEF# or WE#,
whichever occurs last. The data is latched on the
rising edge of either BEF# or WE#, whichever
occurs first.
3. Initiate the internal Program operation after the
rising edge of the fourth WE# or BEF#, whichever
occurs first. The Program operation, once initi-
ated, will be completed, within 10 µs. See Figures
8 and 9 for WE# and BEF# controlled Program
operation timing diagrams, and Figure 24 for flow-
charts.
During the Program operation, the only valid flash Read
operations are Data# Polling and Toggle Bit. During the
internal Program operation, the host is free to perform addi-
tional tasks. During the command sequence, WP# should
be statically held high or low. Any SDP commands loaded
during the internal Program operation will be ignored.
Concurrent Read/Write State Table
Flash PSRAM
Program/Erase Read
Program/Erase Write
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