How to erase IC ATMEL AT28C256 EEPROM

[comsians]

Plz tell me how to erase IC "ATMEL" AT28C256 EEPROM
coz it cause error and cant erase
although niether error in EEPROM nor Programmer and cant erase from programmer
plz tell me the solution as soon as possible
thanx

 

[IanP]

erase eeprom

Try "software chip erase" option from here:
http://www.atmel-grenoble.com/dyn/products/app_notes.asp?family_id=638&part_id=1904
Regards,
IanP

 

[AndrzejM]

how to erase eeprom data

In this type of EEPROM there is a mechanism called"SDP" = software data protection.
If activated you can only read, so attempt to erase it (or change the cell content) ends with failure.
How to set /reset SDP is described in the EEPROM data sheet.