M39432 Datasheet, PDF (14/28 Pages) STMicroelectronics – Single Chip 4 Mbit Flash Memory and 256 Kbit Parallel EEPROM

M39432
Figure 9. Sector Unprotecting Flowchart
START
EE = EF = VIH
n=0
A18, A17, A16 = VIH
A12, A9, A6, G = VIH
Wait 4µs
EF, G, A9 = VID
Wait 4µs
W = VIL
Wait 10ms
W = VIH
EF, G = VIH
Wait 4µs
Verify Sector
Protection Status^1,2
Previous Sector
(Decrement A18, A17, A16)
NO DQ0-7 YES
=
00h
NO ++n
= 1000
YES
FAIL
Last NO
Sector
YES
PASS
AI01949C
Note: 1. The Verify Sector Status operation is specified in Table 10.
2. A6 is kept at V_IH during unprotection algorithm in order to secure best unprotection verification. During all other protection status
reads, A6 must be kept at VIL.
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