The BQ76942 device integrates a 32-byte scratchpad memory which can be used by the customer for storing manufacturing data, such as serial numbers, production or test dates, and so forth. The scratchpad data can be written into OTP memory on the customer production line. This data can only be written while in FULLACCESS mode, although it can be read in all modes. The data is read or written using the 0x0070 MANU_DATA() subcommand.

When written, the data is first updated in RAM. If the Settings:Manufacturing:Mfg Status Init[OTPW_EN] configuration bit is set, the device then attempts to write the data to OTP when CONFIG_UPDATE mode is exited or at the completion of the MANU_DATA() subommand if it was sent while outside of CONFIG_UPDATE mode. The device only writes OTP if the BAT voltage is above the minimum allowed voltage level (the voltage can be above the maximum data sheet value in this case) and the temperature is within the allowed temperature range, as specified in the device data sheet. If conditions do not allow, the write to OTP remains pending and completes when conditions become acceptable.

The restrictions on how bits can be changed using the MANU_DATA() subcommand are described below:

• Outside CONFIG_UPDATE mode:
  • Bits can be changed from '0' to '1' or left unchanged.
• In CONFIG_UPDATE mode:
  • Bits can be changed from '0' to '1' or left unchanged.
  • If a bit is still '0' in OTP, it can be changed from '1' to '0'.
  • If a bit has been set in OTP, it cannot be changed from '1' to '0'.