m28w320fcb STMicroelectronics, m28w320fcb Datasheet - Page 21

• Manufacturer Part Number: m28w320fcb
• Description: 32 Mbit 2mb X16, Boot Block 3v Supply Flash Memory
• Manufacturer: STMicroelectronics

M28W320FCT, M28W320FCB
4.13
4.14
4.15
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.
1.
2.
The lock status can be monitored for each block using the Read Electronic Signature
command.
The Block Lock bits are volatile, once set they remain 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.
Block Unlock command
The Block Unlock command is used to unlock a block, allowing the block to be programmed
or erased. Two Bus Write cycles are required to issue the Block Unlock command.
1.
2.
The lock status can be monitored for each block using the Read Electronic Signature
command.
Refer to the section, Block Locking, for a detailed explanation.
Block Lock-Down command
A locked block cannot be Programmed or Erased, or have its protection status changed
when WP is low, V
locked blocks can be individually unlocked by the Block Unlock command.
Two Bus Write cycles are required to issue the Block Lock-Down command.
1.
2.
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.
Lock-Down command. Refer to the section, Block Locking, for a detailed explanation.
The first bus cycle sets up the Block Lock command.
The second Bus Write cycle latches the block address.
The first bus cycle sets up the Block Unlock command.
The second Bus Write cycle latches the block address.
The first bus cycle sets up the Block Lock command.
The second Bus Write cycle latches the block address.
Table 10
Table 10
IL
. When WP is high, V
shows the protection status after issuing a Block Lock command.
shows the protection status after issuing a Block Unlock command.
Table 10
shows the protection status after issuing a Block
IH,
the Lock-Down function is disabled and the
Command interface
21/69