16 Mbit Concurrent SuperFlash + 2 / 4 Mbit SRAM ComboMemory
SST34HF1621 / SST34HF1641
SST3 4HF16 21/ 164 116 Mb CSF (x1 6) + 2Mb / 4Mb SRAM (x8/x16 ) MCP Co mboMe morie s
Data Sheet
FEATURES:
• Flash Organization: 1M x16
• Dual-Bank Architecture for Concurrent
Read/Write Operation
– 16 Mbit: 12 Mbit + 4 Mbit
• SRAM Organization:
– 2 Mbit: 256K x8 or 128K x16
– 4 Mbit: 512K x8 or 256K x16
• Single 2.7-3.3V Read and Write Operations
• Superior Reliability
– Endurance: 100,000 Cycles (typical)
– Greater than 100 years Data Retention
• Low Power Consumption:
– Active Current: 25 mA (typical)
– Standby Current: 20 µA (typical)
• Hardware Sector Protection (WP#)
– Protects 4 outer most sectors (4 KWord) in the
larger bank by holding WP# low and unprotects
by holding WP# high
• Hardware Reset Pin (RST#)
– Resets the internal state machine to reading
data array
• Sector-Erase Capability
– Uniform 1 KWord sectors
• Block-Erase Capability
– Uniform 32 KWord blocks
• Read Access Time
– Flash: 70 and 90 ns
– SRAM: 70 and 90 ns
• Latched Address and Data
• Fast Erase and Word-Program:
– Sector-Erase Time: 18 ms (typical)
– Block-Erase Time: 18 ms (typical)
– Chip-Erase Time: 70 ms (typical)
– Word-Program Time: 14 µs (typical)
– Chip Rewrite Time: 8 seconds (typical)
• Automatic Write Timing
– Internal
V
P P
Generation
• End-of-Write Detection
– Toggle Bit
– Data# Polling
– Ready/Busy# pin
• CMOS I/O Compatibility
• JEDEC Standard Command Set
• Conforms to Common Flash Memory Interface
(CFI)
• Packages Available
– 56-ball LFBGA (8mm x 10mm)
PRODUCT DESCRIPTION
The SST34HF1621/1641 ComboMemory devices inte-
grate a 1M x16 CMOS flash memory bank with a 256K x8/
128K x16 or 512K x8/ 256K x16 CMOS SRAM memory
bank in a Multi-Chip Package (MCP). These devices are
fabricated using SST’s proprietary, high-performance
CMOS SuperFlash technology incorporating the split-gate
cell design and thick oxide tunneling injector to attain better
reliability and manufacturability compared with alternate
approaches. The SST34HF1621/1641 devices are ideal for
applications such as cellular phones, GPSs, PDAs and
other portable electronic devices in a low power and small
form factor system.
The SST34HF1621/1641 features dual flash memory bank
architecture allowing for concurrent operations between the
two flash memory banks and the SRAM. The devices can
read data from either bank while an Erase or Program
operation is in progress in the opposite bank. The two flash
memory banks are partitioned into 4 Mbit and 12 Mbit with
top or bottom sector protection options for storing boot
code, program code, configuration/parameter data and
user data.
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1
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/Program cycles. The SST34HF1621/1641 devices
offer a guaranteed endurance of 10,000 cycles. Data
retention is rated at greater than 100 years. With high per-
formance Word-Program, the flash memory banks provide
a typical Word-Program time of 14 µsec. The entire flash
memory bank can be erased and programmed word-by-
word in typically 8 seconds for the SST34HF1621/1641,
when using interface features such as T
oggle Bit or Data#
Polling to indicate the completion of Program operation. T
o
protect against inadvertent flash write, the SST34HF1621/
1641 devices contain on-chip hardware and software data
protection schemes.
The SST l ogo a nd Sup erFlash a re regi ste red trade marks of Si lico n Sto rage Te chno logy, Inc.
C oncu rrent Supe rFl ash, CSF, an d Comb oMemo ry are trade marks of Si lico n Sto rage Te chno logy, Inc.
Th ese spe cificatio ns are sub ject to ch ang e witho ut n otice.
16 Mbit Concurrent SuperFlash + 2 / 4 Mbit SRAM ComboMemory
SST34HF1621 / SST34HF1641
Data Sheet
The flash and SRAM operate as two independent memory
banks with respective bank enable signals. The memory
bank selection is done by two bank enable signals. The
SRAM bank enable signal, BES1# and BES2, selects the
SRAM bank. The flash memory bank enable sig nal, BEF#,
has to be used with Software Data Protection (SDP) com-
mand sequence when controlling the Erase and Program
operations in the flash memory bank. The memory banks
are superimposed in the same memory address space
where they share common address lines, data lines, WE#
and OE# which minimize power consumption and area.
Bus contention is elimin ated as the device will not recog-
nize both bank enables as being simultaneously active.
Designed, manufactured, and tested for applications requir-
ing low power and small form factor, the SST34HF1621/
1641 are offered in both commercial and extended temper-
atures and a small footprint package to meet board space
constraint requirements.
C
O NC U R R EN T
R
E A D
/W
R IT E
S
T A T E
T
A B L E
Flash
Bank 1
Read
Write
Write
No Operation
Write
No Operation
Bank 2
Write
Read
No Operation
Write
No Operation
Write
SRAM
No Operation
No Operation
Read
Read
Write
Write
Note:
For the purposes of this table, write means to Block-, Sector,
or Chip-Erase, or Word-Program as applicable to the
appropriate bank.
Flash Read Operation
The Read operation of the SST34HF1621/1641 is
controlled by BEF# and OE#, both have to be low for
the system to obtain data from the outputs. BEF# is
used for devic e selection. When BEF# is high, the
chip is deselected and only standby power is con-
sumed. OE# is the output control and is used to gate
data from the output pins. The data bus is in high
impedance state when either BEF# or OE# is high.
Refer to the Read cycle timing diagram for further
details (Figure 6).
Device Operation
The SST34HF1621/1641 uses BES1#, BES2 and BEF# to
control operation of either the flash or the SRAM memory
bank. When BEF# is low, the flash bank is activated for
Read, Program or Erase operation. When BES1# is low,
and BES2 is hig h the SRAM 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 SRAM
memory banks which minimizes power consumption and
loading. The device goes into standby when BEF# and
BES1# bank enables are raised to V
IHC
(Logic High) or
when BEF# is high and BES2 is low.
Flash Word-Program Operation
The SST34HF1621/1641 are programmed on a word-by-
word basis. Before Program operations, the memory must
be erased first. The Program operation consists of three
steps. The first step is the three-byte load sequence for
Software Data Protection. The second step is to load word
address and word data. During the Word-Program opera-
tion, 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. The third step is the internal Program operation
which is initiated after the rising edge of the fourth WE# or
BEF#, whichever occurs first. The Program operation, once
initiated, will be completed typically within 10 µs. See Fig-
ures 7 and 8 for WE# and BEF# controlled Program opera-
tion timing diagrams and Figure 21 for flowcharts. During
the Program operation, the only valid reads are Data# Poll-
ing and T
oggle Bit. During the internal Program operation,
the host is free to perform additional tasks. Any commands
issued during the internal Program operation are ignored.
Concurrent Read/Write Operation
Dual bank architecture of SST34HF1621/1641 devices
allows the Concurrent Read/Write operation whereby the
user can read from one bank while program or erase in the
other bank. This operation can be used when the user
needs to read system code in one bank while updating
data in the other bank. See Figure 1 for Dual-Bank Memory
Organization.
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16 Mbit Concurrent SuperFlash + 2 / 4 Mbit SRAM ComboMemory
SST34HF1621 / SST34HF1641
Data Sheet
Flash Sector/Block-Erase Operation
The Sector/Block-Erase operation allows the system to
erase the device on a sector-by-sector or block-by-block
basis. The SST34HF1621/1641 offer both Sector-Erase
and Block-Erase mode. The sector architecture is based
on uniform sector size of 1 KWord. The Block-Erase mode
is based on uniform block size of 32 KWord. The Sector-
Erase operation is initiated by executin g a six-byte com-
mand sequence with Sector-Erase command (30H) and
sector address (SA) in the last bus cycle. The Block-Erase
operation is initiated by executing a six-byte command
sequence with Blo ck-Erase command (50H) and blo ck
address (BA) in the last bus cycle . The sector or block
address is latched on the falling edge of the sixth WE#
pulse, while the command (30H or 50H) is latched on the
rising edge of the sixth WE# pulse. The in ternal Erase
operation begins after the sixth WE# pulse. See Figures 12
and 13 for timing waveforms. Any commands issued during
the Sector- or Block-Erase operation are ignored.
The actual completion of the nonvolatile write is asynchro-
nous with the system; therefore, either a Ready/Busy# (RY/
BY#), Data# Polling (DQ
7
) or Toggle Bit (DQ
6
) read may be
simultaneous with the completion of the Write cycle. If this
occurs, the system may possibly get an erroneous result,
i.e., valid data may appear to conflict with either DQ
7
or
DQ
6
. In order to prevent spurious rejection, if an erroneous
result occurs, the software routine should include a loop to
read the accessed location an additional two (2) times. If
both reads are valid, then the device has completed the
Write cycle, otherwise the rejection is valid.
Ready/Busy# (RY/BY#)
The SST34HF1621/1641 includes a Ready/Busy# (RY/
BY#) output signal. RY/BY# is actively pulled low during
internal Program/Erase operation. The status of RY/BY# is
valid after the rising edge of fourth WE# (or CE#) pulse for
Program operation. For Sector-, Block- or Bank-Erase, the
RY/BY# is valid after the rising edge of sixth WE# or (CE#)
pulse. RY/BY# is an open drain output that allows several
devices to be tied in parallel to V
DD
via an external pull up
resistor. Ready/Busy# is in high impedance whenever OE#
or CE# is high or RST# is low.
Flash Chip-Erase Operation
The SST34HF1621/1641 provide a Chip-Erase operation,
which allows the user to erase all unprotected sectors/
blocks to the “1” state. This is useful when the device must
be quickly erased.
The Chip-Erase operation is initiated by executing a six-
byte command sequence with Chip-Erase command (10H)
at address 5555H in the last byte sequence. The Erase
operation begins with the rising edge of the sixth WE# or
BEF#, whichever occurs first. Durin g the Erase operation,
the only valid read is T
oggle Bit or Data# Polling. See T
able
4 for the command sequence, Figure 11 for timing diagram,
and Figure 24 for the flo wchart. Any commands issued dur-
ing the Chip-Erase operation are ignored.
Flash Data# Polling (DQ
7
)
When the SST34HF1621/1641 are in the internal Program
operation, any attempt to read DQ
7
will produce the com-
plement of the true data. Once the Program operation is
completed, DQ
7
will produce true data. Note that even
though DQ
7
may have valid data immediately following the
completion of an internal Write operation, the remaining
data outputs may still be invalid: valid data on the entire
data bus will appear in subsequent successive Read
cycles after an interval of 1 µs. During internal Erase opera-
tion, any attempt to read DQ
7
will produce a ‘0’. Once the
internal Erase operation is completed, DQ
7
will produce a
‘1’. The Data# Polling (DQ
7
) is valid after the rising edge of
fourth WE# (or BEF#) pulse for Program operation. For
Sector-, Block- or Chip-Erase, the Data# Polling (DQ
7
) is
valid after the rising edge of sixth WE# (or BEF#) pulse.
After the completion of a Program operation, Data# Polling
on DQ
7
remains active and the device may not return to the
Read mode for approximately 1 µs. See Figure 9 for Data#
Polling (DQ
7
) timing diagram and Figure 22 for a flowchart.
Flash Write Operation Status Detection
The SST34HF1621/1641 provide one hardware and two
software means to detect the completion of a Write (Pro-
gram or Erase) cycle, in order to optimize the system
Write cycle time. The hardware detection uses the
Ready/Busy# (RY/BY#) pin. The software detection
includes two status bits: Data# Polling (DQ
7
) and T
oggle
Bit (DQ
6
). The End-of-Write detection mode is enabled
after the rising edge of WE#, which initiates the internal
Program or Erase operation.
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16 Mbit Concurrent SuperFlash + 2 / 4 Mbit SRAM ComboMemory
SST34HF1621 / SST34HF1641
Data Sheet
Flash Toggle Bit (DQ
6
)
During the internal Program or Erase operation, any con-
secutive attempts to read DQ
6
will produce alternating 1s
and 0s, i.e., toggling between 1 and 0. When the internal
Program or Erase operation is completed, the DQ
6
bit will
stop toggling. After the completion of a Program operation,
DQ
6
will stop toggling for approximately 1 µs. The device is
then ready for the next operation. The Toggle Bit (DQ
6
) is
valid after the rising edge of fourth WE# (or BEF#) pulse for
Program operation. For Sector-, Block- or Chip-Erase, the
T
oggle Bit (DQ
6
) is valid after the rising edge of sixth WE#
(or BEF#) pulse. See Figure 10 for Toggle Bit timing dia-
gram and Figure 22 for a flowchart.
Hardware Reset (RST#)
The RST# pin provides a hardware method of resetting the
device to read array data. When the RST# pin is held low
for at least T
RP,
any in-progress operation will terminate and
return to Read mode (see Figure 18). When no internal
Program/Erase operation is in progress, a minimum period
of T
RHR
is required after RST# is driven high before a valid
Read can take place (see Figure 17).
The Erase operation that has been interrupted needs to be
reinitiated after the device resumes normal operation mode
to ensure data integrity.
Software Data Protection (SDP)
The SST34HF1621/1641 provide the JEDEC standard
Software Data Protection scheme for all data alteration
operations, i.e., Program and Erase. Any Program operation
requires the inclusion of the three-byte sequence. The
three-byte load sequence is used to initiate the Program
operation, providing optimal protection from inadvertent
Write operations, e.g., during the system power-up or
power-down. Any Erase operation requires the inclusion of
six-byte sequence. The SST34HF1621/1641 are shipped
with the Software Data Protection permanently enabled.
See T
able 4 for the specific software command codes. Dur-
ing SDP command sequence, invalid commands will abort
the device to Read mode within T
RC.
The contents of DQ
15
-
DQ
8
are “Don’t Care” during any SDP command sequence.
Data Protection
The SST34HF1621/1641 provide both hardware
and software features to protect nonvolatile data
from inadvertent writes.
Hardware Data Protection
Noise/Glitch Protection: A WE# or BEF# pulse of less than
5 ns will not initiate a Write cycle.
V
DD
Power Up/Down Detection: The Write operation is
inhibited when V
D D
is less than 1.5V.
Write Inhibit Mode: Forcing OE# low, BEF# high, or WE#
high will inhibit the Write operation. This prevents inadvert-
ent writes during power-up or power-down.
Common Flash Memory Interface (CFI)
Hardware Block Protection
The SST34HF1621/1641 provide a hardware blo ck protec-
tion which protects the outermost 4 KWord in the larger
bank.The blo ck is protected when WP# is held low. See
Fig ure 1 for Block-Protection location.
A user can disable block protection by driving WP# high
thus allowing erase or program of data into the protected
sectors. WP# must be held high prior to issuing the write
command and remain stable until after the entire Write
operation has completed.
The SST34HF1621/1641 also contain the CFI information
to describe the characteristics of the device. In order to
enter the CFI Query mode, the system must write three-
byte sequence, same as Software ID Entry command with
98H (CFI Query command) to address 555H in the last byte
sequence. Once the device enters the CFI Query mode, the
system can read CFI data at the addresses given in T
ables
5 through 7. The system must write the CFI Exit command
to return to Read mode from the CFI Query mode.
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16 Mbit Concurrent SuperFlash + 2 / 4 Mbit SRAM ComboMemory
SST34HF1621 / SST34HF1641
Data Sheet
Product Identification
The Product Identification mode identifies the devices as
the SST34HF1621/1641 and manufacturer as SST. This
mode may be accessed by software operations only. The
hardware device ID Read operation, which is typically used
by programmers cannot be used on this device because of
the shared lines between flash and SRAM in the multi-chip
package. Therefore, application of high voltage to pin A
9
may damage this device. Users may use the software
Product Identification operation to identify the part (i.e.,
using the device ID) when using multiple manufacturers in
the same socket. For details, see Tables 3 and 4 for soft-
ware operation, Figure 14 for the software ID entry and
read timing diagram and Figure 23 for the ID entry com-
mand sequence flowchart.
TABLE
1: P
R OD U C T
I
DE N T IF IC A T IO N
ADDRESS
Manufacturer’s ID
Device ID
SST34HF1621
SST34HF1641
0001H
0001H
2761H
2761H
T1.2 523
SRAM Operation
With BES1# low, BES2 and BEF# high, the
SST34HF162x operates as 256K x8 or 128K x16 CMOS
SRAM, and the SST34HF164x operates as 512K x8 or
256K x16 CMOS SRAM, with fully static operation requir-
ing no external clocks or timing strobes. The CIOs pin
configures the SRAM for x8 or x16 SRAM operation
modes. The SST34HF162x SRAM is mapped into the
first 256 KByte/128 KWord address space of the device,
and the SST34HF164x SRAM is mapped into the first
512 KByte/256 KWord address space. When BES1#,
BEF# are high and BES2 is low, all memory banks are
deselected and the device enters standby. Read and
Write cycle times are equal. The control signals UBS#
and LBS# provide access to the upper data byte and
lower data byte. See T
able 3 for SRAM Read and Write
data byte control modes of operation.
DATA
00BFH
0000H
SRAM Read
The SRAM Read operation of the SST34HF1621/1641 is
controlled by OE# and BES1#, both have to be low with
WE# and BES2 high for the system to obtain data from the
outputs. BES1# and BES2 are used for SRAM bank selec-
tion. 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 the Read cycle timing diagram,
Figure 3, for further details.
Product Identification Mode Exit/
CFI Mode Exit
In order to return to the standard Read mode, the Software
Product Identification mode must be exited. Exit is accom-
plished by issuing the Software ID Exit command
sequence, which returns the device to the Read mode.
This command may also be used to reset the device to the
Read mode after any inadvertent transient condition that
apparently causes the device to behave abnormally, e.g.,
not read correctly. Please note that the Software ID Exit/
CFI Exit command is ignored during an internal Program or
Erase operation. See T
able 4 for software command
codes, Figure 16 for timing waveform and Figure 23 for a
flowchart.
SRAM Write
The SRAM Write operation of the SST34HF1621/1641 is
controlled by WE# and BES1#, both have to be low, BES2
have to be high for the system to write to the SRAM. During
the Word-Write operation, the addresses and data are ref-
erenced to the rising edge of either BES1#, WE#, or the
falling edge of BES2 whichever occurs first. The write time
is measured from the last falling edge of BES#1 or WE# or
the rising edge of BES2 to the first rising edge of BES1#, or
WE# or the falling edge of BES2. Refer to the Write cycle
timing diagram, Figures 4 and 5, for further details.
©200 2 Sili con Storag e Te chno log y, Inc.
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