AT28C040-20FI ATMEL [ATMEL Corporation], AT28C040-20FI Datasheet - Page 10

• Manufacturer Part Number: AT28C040-20FI
• Description: 4-Megabit (512K x 8) Paged Parallel EEPROMs
• Manufacturer: ATMEL [ATMEL Corporation]

20. Software Protected Program Cycle Waveform
Notes:
18. Software Data
Notes:
10
Protection Enable Algorithm
1. Data Format: I/O7 - I/O0 (Hex);
2. Write Protect state will be activated at end of write
3. Write Protect state will be deactivated at end of write
4. 1 to 256 bytes of data are loaded.
1. A0 - A14 must conform to the addressing sequence for the first 3 bytes as shown above.
2. After the command sequence has been issued and a page write operation follows, the page address inputs (A8 - A18) must
3. OE must be high only when WE and CE are both low.
AT28C040
be the same for each high to low transition of WE (or CE).
Address Format: A14 - A0 (Hex).
even if no other data is loaded.
period even if no other data is loaded.
LOAD LAST BYTE
ANY ADDRESS
ADDRESS 2AAA
LAST ADDRESS
LOAD DATA AA
ADDRESS 5555
ADDRESS 5555
LOAD DATA XX
LOAD DATA 55
LOAD DATA A0
TO
TO
TO
TO
TO
(4)
WRITES ENABLED
ENTER DATA
PROTECT STATE
(2)
(1)
19. Software Data
Protection Disable Algorithm
(1)(2)(3)
LOAD LAST BYTE
ANY ADDRESS
ADDRESS 2AAA
ADDRESS 2AAA
LAST ADDRESS
ADDRESS 5555
ADDRESS 5555
ADDRESS 5555
ADDRESS 5555
LOAD DATA AA
LOAD DATA AA
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
(3)
0542E–PEEPR–1/08
(1)