AT28C64B_06 Datasheet, PDF (10/18 Pages) ATMEL Corporation – 64K (8K x 8) Parallel EEPROM with Page Write and Software Data Protection

19. Software Data Protection Enable
Algorithm⁽¹⁾
20. Software Data Protection Disable
Algorithm⁽¹⁾
LOAD DATA AA
TO
ADDRESS 1555
LOAD DATA AA
TO
ADDRESS 1555
LOAD DATA 55
TO
ADDRESS 0AAA
LOAD DATA 55
TO
ADDRESS 0AAA
LOAD DATA A0
TO
ADDRESS 1555
WRITES ENABLED⁽²⁾
LOAD DATA 80
TO
ADDRESS 1555
LOAD DATA XX
TO
ANY ADDRESS⁽⁴⁾
LOAD DATA AA
TO
ADDRESS 1555
LOAD LAST BYTE
TO
LAST ADDRESS
ENTER DATA
PROTECT STATE
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 55
TO
ADDRESS 0AAA
LOAD DATA 20
TO
ADDRESS 1555
LOAD DATA XX
TO
ANY ADDRESS⁽⁴⁾
EXIT DATA
PROTECT STATE⁽³⁾
LOAD LAST BYTE
TO
LAST ADDRESS
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.
21. Software Protected Write Cycle Waveforms⁽¹⁾⁽²⁾
OE
CE
t_WPH
t_BLC
t_WP
WE
t_AS
t_AH
t_DH
A0 -A5
A6 - A12
t_DS
DATA
t_WC
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.
10 AT28C64B
0270K–PEEPR–10/06