Non-Volatile Memory Lock Bits

The device provides two Lock Bits.

Table 1. Lock Bit Byte
Lock Bit Byte Bit No. Description Default Value
  7   1 (unprogrammed)
  6   1 (unprogrammed)
  5   1 (unprogrammed)
  4   1 (unprogrammed)
  3   1 (unprogrammed)
  2   1 (unprogrammed)
NVLB2 1 Non-Volatile Lock Bit 1 (unprogrammed)
NVLB1 0 Non-Volatile Lock Bit 1 (unprogrammed)

The Lock Bits can be left unprogrammed ("1") or can be programmed ("0") to obtain the additional security. Lock Bits can be erased to "1" with the Chip Erase command, only.

Table 2. Lock Bit Protection Modes
Memory Lock Bits(1) Protection Type
LB Mode NVLB2(2) NVLB1(2)
1 1 1 No memory lock features enabled.
2 1 0 Further Programming of the Flash memory is disabled in the external programming mode. The configuration section bits are locked in the external programming mode
3 0 0 Further programming and verification of the flash is disabled in the external programming mode. The configuration section bits are locked in the external programming mode
Note:
  1. Program the configuration section bits before programming NVLB1 and NVLB2.
  2. "1" means unprogrammed, "0" means programmed