HN58S256AT-20 HITACHI [Hitachi Semiconductor], HN58S256AT-20 Datasheet - Page 15

• Manufacturer Part Number: HN58S256AT-20
• Description: 256 k EEPROM (32-kword x 8-bit)
• Manufacturer: HITACHI [Hitachi Semiconductor]

3. Software data protetion
To prevent unintentional programming caused by noise generated by external circuits. This device has
the software data protection function. In software data protection mode, 3 bytes of data must be input
before write data as follows. And these bytes can switch the non-protection mode to the protection mode.
SDP is not enabled if only the 3 bytes code is input.
Software data protection mode can be cancelled by inputting the following 6 bytes. After that, this device
turns to the non-protection mode and can write data normally. But when the data is input in the
cancelling cycle, the data cannot be written.
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.
Write address
Address
2AAA
5555
5555
Address
2AAA
2AAA
5555
5555
5555
5555
Write data }
Data
AA
A0
55
Normal data input
Data
AA
AA
55
80
55
20
HN58S256A Series