HN58C256A Datasheet, PDF (20/25 Pages) Hitachi Semiconductor – 256k EEPROM (32-kword x 8-bit) Ready/Busy and RES function (HN58C257A)

HN58C256A Series, HN58C257A Series
3. Software data protection
To prevent unintentional programming, this device has the software data protection (SDP) mode. The SDP is
enabled by inputting the following 3 bytes code and write data. SDP is not enabled if only the 3 bytes code is
input. To program data in the SDP enable mode, 3 bytes code must be input before write data.
Address
Data
5555
AA
↓
↓
2AAA
55
↓
↓
5555
A0
↓
↓
Write address Write data } Normal data input
The SDP mode is disabled by inputting the following 6 bytes code. Note that, if data is input in the SDP
disable cycle, data can not be written.
Address
5555
↓
2AAA
↓
5555
↓
5555
↓
2AAA
↓
5555
Data
AA
↓
55
↓
80
↓
AA
↓
55
↓
20
The software data protection is not enabled at the shipment.
Note: There are some differences between Hitachi’s and other company’s for enable/disable sequence of
software data protection. If there are any questions , please contact with Hitachi sales offices.
20