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