m28256 STMicroelectronics, m28256 Datasheet - Page 6

• Manufacturer Part Number: m28256
• Description: 256 Kbit 32kb X8 Parallel Eeprom With Software Data Protection
• Manufacturer: STMicroelectronics

M28256
Figure 5. Software Data Protection Enable Algorithm and Memory Write
Figure 6. Software Data Protection Disable Algorithm
6/21
Instruction
Page
Write
SDP ENABLE ALGORITHM
Address 2AAAh
Address 5555h
Address 5555h
WRITE AAh in
WRITE 55h in
WRITE A0h in
SDP is set
Instruction
Page
Write
tWC (Write Cycle time)
Unprotected State
Address 2AAAh
Address 2AAAh
Address 5555h
Address 5555h
Address 5555h
Address 5555h
WRITE AAh in
WRITE AAh in
WRITE 55h in
WRITE 80h in
WRITE 55h in
WRITE 20h in
after
Instruction
Page
Write
in Memory
AI01699B
Write
SDP
Set
Address 2AAAh
Address 5555h
Address 5555h
WRITE Data to
WRITE AAh in
WRITE A0h in
WRITE 55h in
be Written in
any Address
Write Data
after tWC
SDP Set
not Set
AI01698B
SDP
+
WRITE
is enabled