AT28C64B-20 ATMEL [ATMEL Corporation], AT28C64B-20 Datasheet - Page 8

• Manufacturer Part Number: AT28C64B-20
• Description: 64K (8K x 8) CMOS E2PROM with Page Write and Software Data Protection
• Manufacturer: ATMEL [ATMEL Corporation]

Software Data Protection
Enable Algorithm
Notes for software program code:
Software Protected Write Cycle Waveforms
Notes:
8
1. Data Format: I/O7 - I/O0 (Hex);
2. Write Protect state will be activated at end of
3. Write Protect state will be deactivated at end of
4. 1 to 64 bytes of data are loaded.
Address Format: A12 - A0 (Hex).
write even if no other data is loaded.
write period even if no other data is loaded.
1.
2.
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.
OE must be high only when WE and CE are both low.
LOAD LAST BYTE
ANY ADDRESS
ADDRESS 0AAA
LAST ADDRESS
LOAD DATA AA
ADDRESS 1555
ADDRESS 1555
LOAD DATA XX
LOAD DATA A0
LOAD DATA 55
TO
TO
TO
TO
TO
AT28C64B
(1)
(4)
WRITES ENABLED
ENTER DATA
PROTECT STATE
(2)
Software Data Protection
Disable Algorithm
(1)(2)
LOAD LAST BYTE
ANY ADDRESS
ADDRESS 0AAA
ADDRESS 0AAA
LAST ADDRESS
LOAD DATA AA
ADDRESS 1555
ADDRESS 1555
LOAD DATA AA
ADDRESS 1555
ADDRESS 1555
LOAD DATA XX
LOAD DATA 55
LOAD DATA 80
LOAD DATA 55
LOAD DATA 20
TO
TO
TO
TO
TO
TO
TO
TO
(1)
(4)
EXIT DATA
PROTECT STATE
(3)