M58LT128HST, M58LT128HSB
Block protection
9
Block protection
The M58LT128HST/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.
●
Protect/unprotect: this first level allows software only control of block protection.
≤V : the second level offers a complete hardware protection against Program
●
V
PP
PPLK
and Erase operations on all blocks.
The protection status of each block can be set to protected and unprotected. Appendix C,
Figure 25 shows a flowchart for the protection operations.
9.1
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 Table 7 output the protection status of that block.
The protection status is represented by DQ0. DQ0 indicates the block protect/unprotect
status. It is set by the Protect command and cleared by the Unprotect command.
The following sections explain the operation of the protection system.
9.2
9.3
Protected state
The default state 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 return an error in the Status Register. The
state 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 state
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.
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NUMONYX [ NUMONYX B.V ]
