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SST34HF1621C Datasheet PDF : 38 Pages
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16 Mbit Concurrent SuperFlash + 2/4 Mbit SRAM ComboMemory
SST34HF1621C / SST34HF1641C
Data Protection
The SST34HF16x1C 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.
VDD Power Up/Down Detection: The Write operation is
inhibited when VDD 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.
Hardware Block Protection
The SST34HF16x1C provide a hardware block protection
which protects the outermost 8 KWord in Bank 1. The block
is protected when WP# is held low. See Figures 2 and 3 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. If WP# is left floating, it is inter-
nally held high via a pull-up resistor, and the Boot Block is
unprotected, enabling Program and Erase operations on
that block.
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 TRP, any in-progress operation will terminate and
return to Read mode, see Figure 21. When no internal Pro-
gram/Erase operation is in progress, a minimum period of
TRHR is required after RST# is driven high before a valid
Read can take place, see Figure 20.
The Erase operation that has been interrupted needs to be
reinitiated after the device resumes normal operation mode
to ensure data integrity. See Figures 20 and 21 for timing
diagrams.
Data Sheet
Software Data Protection (SDP)
The SST34HF16x1C provide the JEDEC standard Soft-
ware Data Protection scheme for all data alteration opera-
tions, 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 SST34HF16x1C are shipped with
the Software Data Protection permanently enabled. See
Table 5 for the specific software command codes. During
SDP command sequence, invalid commands will abort the
device to Read mode within TRC. The contents of DQ15-
DQ8 are “Don’t Care” during any SDP command
sequence.
Common Flash Memory Interface (CFI)
These devices also contain the CFI information to describe
the characteristics of the devices. In order to enter the CFI
Query mode, the system must write the three-byte
sequence same as the Software ID Entry command with
98H (CFI Query command) to address 555H in the last
byte sequence. For CFI Entry and Bead timing diagram,
See Figure 18. Once the device enters the CFI Query
mode, the system can read CFI data a t the addresses
given in Tables 7 and 9. The system must write the CFI Exit
command to return to Bead mode from the CFI Query
mode.
Security ID
The SST34HF16x1C devices offer a 256-bit Security ID
space. The Secure ID space is divided into two 128-bit seg-
ments—one factory programmed segment and one user
programmed segment. The first segment is programmed
and locked at SST with a unique, 128-bit number. The user
segment is left un-programmed for the customer to pro-
gram as desired. To program the user segment of the
Security ID, the user must use the Security ID Program
command. End-of-Write status is checked by reading the
toggle bits. Data# Polling is not used for Security ID End-of-
Write detection. Once programming is complete, the Sec
ID should be locked using the User-Sec-ID-Program-Lock-
Out. This disables any future corruption of this space. Note
that regardless of whether or not the Sec ID is locked, nei-
ther Sec ID segment can be erased. The Secure ID space
can be queried by executing a three-byte command
sequence with Query-Sec-ID command (88H) at address
555H in the last byte sequence. To exit this mode, the Exit-
Sec-ID command should be executed. Refer to Table 5 for
more details.
©2006 Silicon Storage Technology, Inc.
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S71252-03-000
8/06
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