FM20L08_07 Datasheet, PDF (6/14 Pages) Ramtron International Corporation – 1Mbit Bytewide FRAM Memory - Industrial Temp.

FM20L08 - Industrial Temp.
Normal Memory
Operation
Any other
operation
n
Read 05555h?
y
Read
n
1AAAAh?
y
n
Read 03333h?
y
Read
n
1CCCCh?
y
n
Read 100FFh?
y
n
Read 0FF00?
y
n
Write 1AAAA?
y
Hold Data Byte
n
Write 1CCCC?
y
n
Data
Complement?
y
Write 0FF00
Read 00000
Eprnotetercnt 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 00000h to 07FFFh and 10000h to 13FFFh
(sectors 0, 1 & 4):
Address
Read 05555h
Read 1AAAAh
Read 03333h
Read 1CCCCh
Read 100FFh
Read 0FF00h
Write 1AAAAh
Write 1CCCCh
Write 0FF00h
Read 00000h
Data
-
-
-
-
-
-
13h
Ech
-
-
; bits 0, 1, 4 = 1
; complement of 13h
; Data is don’t care
; return to Normal Operation
Rev. 1.72
May 2007
Page 6 of 14