AT28C040-20 ATMEL Corporation, AT28C040-20 Datasheet - Page 8

• Manufacturer Part Number: AT28C040-20
• Description: 4-Megabit 512K x 8 Paged E2PROM
• Manufacturer: ATMEL Corporation

Software Data
Protection Enable Algorithm
Notes:
Software Protected Program Cycle Waveform
Notes:
8
1.
2.
3.
4.
1.
2.
3.
Data Format: I/O7 - I/O0 (Hex);
Address Format: A14 - A0 (Hex).
Write Protect state will be activated at end of write
even if no other data is loaded.
Write Protect state will be deactivated at end of write
period even if no other data is loaded.
1 to 25 bytes of data are loaded.
A0 - A14 must conform to the addressing sequence for the first 3 bytes as shown above.
After the command sequence has been issued and a page write operation follows, the page address inputs (A8 - A18) must
be the same for each high to low transition of WE (or CE).
OE must be high only when WE and CE are both low.
ANY ADDRESS
LOAD LAST BYTE
ADDRESS 2AAA
LAST ADDRESS
ADDRESS 5555
ADDRESS 5555
LOAD DATA AA
LOAD DATA XX
LOAD DATA A0
LOAD DATA 55
TO
TO
TO
TO
TO
AT28C040
(4)
WRITES
ENABLED
ENTER DATA
PROTECT STATE
(1)
(2)
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
(1)
(3)