M28W160CT, M28W160CB
The Protection Register Program cannot be sus-
pended. See Appendix C, Figure 23, Protection
Register Program Flowchart and Pseudo Code,
for the flowchart for using the Protection Register
Program command.
■ The first bus cycle sets up the Block Unlock
command.
■ The second Bus Write cycle latches the block
address.
The lock status can be monitored for each block
using the Read Electronic Signature command.
Table. 10 shows the protection status after issuing
a Block Unlock command. Refer to the section,
Block Locking, for a detailed explanation.
Block Lock Command
The Block Lock command is used to lock a block
and prevent Program or Erase operations from
changing the data in it. All blocks are locked at
power-up or reset.
Two Bus Write cycles are required to issue the
Block Lock command.
Block Lock-Down Command
A locked block cannot be Programmed or Erased,
or have its protection status changed when WP is
low, V . When WP is high, V the Lock-Down
IL IH,
function is disabled and the locked blocks can be
individually unlocked by the Block Unlock com-
mand.
■ The first bus cycle sets up the Block Lock
command.
■ The second Bus Write cycle latches the block
address.
Two Bus Write cycles are required to issue the
Block Lock-Down command.
The lock status can be monitored for each block
using the Read Electronic Signature command.
Table. 10 shows the protection status after issuing
a Block Lock command.
■ The first bus cycle sets up the Block Lock
command.
The Block Lock bits are volatile, once set they re-
main set until a hardware reset or power-down/
power-up. They are cleared by a Blocks Unlock
command. Refer to the section, Block Locking, for
a detailed explanation.
■ The second Bus Write cycle latches the block
address.
The lock status can be monitored for each block
using the Read Electronic Signature command.
Locked-Down blocks revert to the locked (and not
locked-down) state when the device is reset on
power-down. Table. 10 shows the protection sta-
tus after issuing a Block Lock-Down command.
Refer to the section, Block Locking, for a detailed
explanation.
Block Unlock Command
The Blocks Unlock command is used to unlock a
block, allowing the block to be programmed or
erased. Two Bus Write cycles are required to is-
sue the Blocks Unlock command.
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NUMONYX [ NUMONYX B.V ]
