M58LT256JSB8ZA6 STMICROELECTRONICS [STMicroelectronics], M58LT256JSB8ZA6 Datasheet - Page 48

• Manufacturer Part Number: M58LT256JSB8ZA6
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Block protection
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Block protection
The M58LT256JST/B features an instant, individual block protection scheme that allows any
block to be protected or unprotected with no latency. This protection scheme has two levels
of protection.
The protection status of each block can be set to Protected and Unprotected.
Figure
Reading a block’s protection status
The protection status of every block can be read in the Read Electronic Signature mode of
the device. To enter this mode issue the Read Electronic Signature command. Subsequent
reads at the address specified in
The protection status is represented by DQ0. DQ0 indicates the Block Protect/Unprotect
status and is set by the Protect command and cleared by the Unprotect command.
The following sections explain the operation of the protection system.
Protected state
The default status of all blocks on power-up or after a hardware reset is Protected (state =
1). Protected blocks are fully protected from program or erase operations. Any program or
erase operations attempted on a protected block will return an error in the Status Register.
The status of a protected block can be changed to Unprotected using the appropriate
software commands. An Unprotected block can be protected by issuing the Protect
command.
Unprotected state
Unprotected blocks (state = 0), can be programmed or erased. All unprotected blocks return
to the Protected state after a hardware reset or when the device is powered-down. The
status of an unprotected block can be changed to Protected using the appropriate software
commands. A protected block can be unprotected by issuing the Unprotect command.
Protect/Unprotect - this first level allows software only control of block protection.
V
and erase on all blocks.
PP
25, shows a flowchart for the protection operations.
≤ V
PPLK
- the second level offers a complete hardware protection against program
Table
7, will output the protection status of that block.
M58LT256JST, M58LT256JSB
Appendix
C,