10
0270L–PEEPR–2/09
AT28C64B
19. Software Data Protection Enable
Algorithm
(1)
Notes: 1. Data Format: I/O7 - I/O0 (Hex);
Address Format: A12 - A0 (Hex).
2. Write Protect state will be activated at end of write
even if no other data is loaded.
3. Write Protect state will be deactivated at end of write
period even if no other data is loaded.
4. 1 to 64 bytes of data are loaded.
LOAD DATA AA
TO
ADDRESS 1555
LOAD DATA 55
TO
ADDRESS 0AAA
LOAD DATA A0
TO
ADDRESS 1555
LOAD DATA XX
TO
ANY ADDRESS
(4)
LOAD LAST BYTE
TO
LAST ADDRESS
ENTER DATA
PROTECT STATE
WRITES ENABLED
(2)
20. Software Data Protection Disable
Algorithm
(1)
Notes: 1. Data Format: I/O7 - I/O0 (Hex);
Address Format: A12 - A0 (Hex).
2. Write Protect state will be activated at end of write
even if no other data is loaded.
3. Write Protect state will be deactivated at end of write
period even if no other data is loaded.
4. 1 to 64 bytes of data are loaded.
LOAD DATA AA
TO
ADDRESS 1555
LOAD DATA 55
TO
ADDRESS 0AAA
LOAD DATA 80
TO
ADDRESS 1555
LOAD DATA AA
TO
ADDRESS 1555
LOAD DATA 20
TO
ADDRESS 1555
LOAD DATA XX
TO
ANY ADDRESS
(4)
LOAD LAST BYTE
TO
LAST ADDRESS
LOAD DATA 55
TO
ADDRESS 0AAA
EXIT DATA
PROTECT STATE
(3)
21. Software Protected Write Cycle Waveforms
(1)(2)
Notes: 1. A6 through A12 must specify the same page address during each high to low transition of WE (or CE) after the software
code has been entered.
2. OE must be high only when WE and CE are both low.
OE
WE
CE
A6 - A12
DATA
A0 -A5
t
AS
t
AH
t
DS
t
DH
t
WP
t
WPH
t
BLC
t
WC
