Nand flash OTP

Typical Nand flash OTP features:

• The OTP area must be programmed once because it is impossible to be performed erase operation. And the OTP area
  can be partially programmed up to 8times(4 for main and 4 for spare) like main cell array.

• When OTP area is partially programed by more than one time, the part of the page where had been programmed must
  not be over written, thus the user must be very careful about addressing. Because the programmed part may be changed
  from 1 to 0 but it may not be changed from 0 to 1 if the programmed part is programmed again without erase operation.
  

• The OTP area can be read more than once.

Typical Read/Write Operations:

• OTP entry commands are required to access OTP area.

• Once the OTP entry commands are given, OTP operation (Program or Read) may be continuously executed
  without another extra OTP entry commands.
  

• To exit OTP after all operations are finished, OTP exit command is required.

• Vcc must be kept at operating voltage during operation.