FM22LD16_13 Datasheet, PDF (6/15 Pages) Cypress Semiconductor – 4Mbit F-RAM Memory

FM22LD16 - 256Kx16 FRAM
Normal Memory
Operation
Any other
operation
n
Read 24555h?
y
n
Read 3AAAAh?
y
n
Read 02333h?
y
Read
n
1CCCCh?
y
n
Read 000FFh?
y
n
Read 3EF00?
y
n
Write 3AAAA?
y
Hold Data Byte
n
Write 1CCCC?
y
Write 0FF00?
Read 00000?
n
Data
Complement?
y
Eprnotteercnt esweyttwinrgites
n
Write 1CCCC?
y
Read 1AAAA?
Drive write protect
data out
Read 00000?
Sequence Detector
Change Write Protect
Settings
Read Write Protect
Settings
Figure 2. Write-Protect State Machine
For example, the following sequence write-protects addresses from 18000h to 27FFFh (sectors 3 & 4):
Address
Read 24555h
Read 3AAAAh
Read 02333h
Read 1CCCCh
Read 000FFh
Read 3EF00h
Write 3AAAAh
Write 1CCCCh
Write 0FF00h
Read 00000h
Data
-
-
-
-
-
-
18h
E7h
-
-
; bits 3 & 4 = 1
; complement of 18h
; Data is don’t care
; return to Normal Operation
Document Number: 001-86190 Rev. **
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