AT28C256 ATMEL Corporation, AT28C256 Datasheet - Page 8

• Manufacturer Part Number: AT28C256
• Description: 256K 32K x 8 Paged CMOS E2PROM
• Manufacturer: ATMEL Corporation

Software Protected Write Cycle Waveforms
Notes: 1. A6 through A14 must specify the same page address during each high to low transition of WE (or CE) after
Software Data
Protection Enable Algorithm
Notes for software program code:
1. Data Format: I/O7 - I/O0 (Hex);
2. Write Protect state will be activated at end of write even if no
3. Write Protect state will be deactivated at end of write period
4. 1 to 64-bytes of data are loaded.
2-224
Address Format: A14 - A0 (Hex).
other data is loaded.
even if no other data is loaded.
2. OE must be high only when WE and CE are both low.
the software code has been entered.
LOAD LAST BYTE
ADDRESS 2AAA
ANY ADDRESS
LAST ADDRESS
ADDRESS 5555
ADDRESS 5555
LOAD DATA AA
LOAD DATA XX
LOAD DATA 55
LOAD DATA A0
TO
TO
TO
TO
TO
AT28C256
(4)
WRITES ENABLED
ENTER DATA
PROTECT STATE
(1)
(2)
Software Data
Protection Disable Algorithm
(1, 2)
LOAD LAST BYTE
ANY ADDRESS
ADDRESS 2AAA
ADDRESS 2AAA
LAST ADDRESS
LOAD DATA AA
ADDRESS 5555
ADDRESS 5555
LOAD DATA AA
ADDRESS 5555
ADDRESS 5555
LOAD DATA XX
LOAD DATA 55
LOAD DATA 80
LOAD DATA 55
LOAD DATA 20
TO
TO
TO
TO
TO
TO
TO
TO
(4)
EXIT DATA
PROTECT STATE
(1)
(3)