Figure 12
Sector Unprotect Algorithm
Start
Set VCC = 5.0 V
Protect All Sectors
PLSCNT = 1
Set Up Sector Address
Unprotected Mode
(A12 = A7 = VIH, A6 = VIL)
Set VCC = 5.0 V
Set
OE = CE = A9 = VID
Activate WE Pulse
Time Out 10ms
Increment
PLSCNT
Set OE = CE = VIL
Remove VID from A9
Set VCC = 4.25 V
Write Autoselect
Command Sequence
Setup Sector Address SA0
Set A1 = 1, A0 = 0
Read Data
From Device
No
Increment
No
Write Reset
Command
Data = 00H
?
PLSCNT = 1000
?
Sector Address
Yes
Yes
Device Failure
Sector
No
Address = SA7
?
Yes
Set VCC = 5.0 V
Notes:
SA0 = Sector Address for initial sector
SA7 = Sector Address for last sector
Please refer to Table 2
Write Reset Command
Sector Unprotect
Completed
16
Aeroflex Circuit Technology
SCD1667 REV A 4/28/97 Plainview NY (516) 694-6700
AEROFLEX [ AEROFLEX CIRCUIT TECHNOLOGY ]
