Document Number: 002-00948 Rev. *C
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S29CD016J
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9.
Secured Silicon Sector Flash Memory Region
The Secured Silicon Sector provides an extra Flash memory region that enables permanent part identification through an Electronic
Serial Number (ESN). The Secured Silicon Sector is a 256-byte flash memory area that is either programmable at the customer, or
by Cypress at the request of the customer. See
for the Secured Silicon Sector address ranges.
All Secured Silicon reads outside of the 256-byte address range return invalid data.
The device allows Simultaneous Read/Write operation while the Secured Silicon Sector is enabled. However, several restrictions
are associated with Simultaneous Read/Write operation and device operation when the Secured Silicon Sector is enabled:
1. The Secured Silicon Sector is not available for reading while the Password Unlock, any PPB program/erase operation, or
Password programming are in progress. Reading to any location in the small bank will return the status of these
operations until these operations have completed execution.
2. Programming the DYB associated with the overlaid boot-block sector results in the DYB NOT being updated. This occurs
only when the Secured Silicon sector is not enabled.
3. Reading the DYB associated with the overlaid boot-block sector when the PPB Lock/DYB Verify command is issued,
causes the read command to return invalid data. This function occurs only when the Secured Silicon Sector is not
enabled.
4. All commands are available for execution when the Secured Silicon Sector is enabled, except the following:
a. Any Unlock Bypass command
b. CFI
c. Accelerated Program
d. Program and Sector Erase Suspend
e. Program and Sector Erase Resume
Issuing the above commands while the Secured Silicon Sector is enabled results in the command being ignored.
5. It is valid to execute the Sector Erase command on any sector other than the Secured Silicon Sector when the Secured
Silicon Sector is enabled. However, it is not possible to erase the Secured Silicon Sector using the Sector Erase
Command, as it is a one-time programmable (OTP) area that can not be erased.
6. Executing the Chip Erase command is permitted when the Secured Silicon Sector is enabled. The Chip Erase command
erases all sectors in the memory array, except for sector 0 in top-boot block configuration, or sector 45 in bottom-boot
block configuration. The Secured Silicon Sector is a one-time programmable memory area that cannot be erased.
7. Executing the Secured Silicon Sector Entry command during program or erase suspend mode is allowed. The Sector
Erase/Program Resume command is disabled when the Secured Silicon sector is enabled; the user cannot resume
programming of the memory array until the Exit Secured Silicon Sector command is written.
8. Address range 00040h–007FFh for the top bootblock, and FF00h–FFF7Fh return invalid data when addressed with the
Secured Silicon sector enabled.
9. The Secured Silicon Sector Entry command is allowed when the device is in either program or erase suspend modes. If
the Secured Silicon sector is enabled, the program or erase suspend command is ignored. This prevents resuming either
programming or erasure on the Secured Silicon sector if the overlayed sector was undergoing programming or erasure.
The host system must ensure that the device resume any suspended program or erase operation after exiting the
Secured Silicon sector.
Table 16. Secured Silicon Sector Addresses
Ordering Option
Sector Size (Bytes)
Address Range
Top Boot
256
00000h-0003Fh (16 Mb and 32 Mb)
Bottom Boot
256
FFFC0h–FFFFFh (32 Mb)
7FFC0h–7FFFFh (16 Mb)
