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BQ79616: BQ79616 lock the OTP Registers after writing

Part Number: BQ79616
Other Parts Discussed in Thread: BQ79600EVM, USB2ANY


we are using BQs in our BMS Product at BMZ Group GmbH in Germany.

Writing some Values into the OTP Registers then reading them, everything works fine.  I read what I wrote.

When I disconnect my BMS (that contains the BQ) from Power Supply for a Minute then connect it again, i read the OTP Registers all at Zero.  So, my thinking is that the BQ does not have an EEPROM to hold the Data on its OTP Registers.

One colleague of mine was in contact with your Techniker located at TI in Nurenberg.  The TI-Techniker told him: to hold the Values in the OTP Registers, after writing you must lock the Fuses and don't keep them unlocked.

I then read the Datasheet of the BQ (Model BQ79616), there is not word about Fuse or EEPROM or lock and unlock.

My question: I want the BQ holds the written Values in its OTP Registers forever, even after new Start, what to do? We have the TI Tools USB2ANY Explorer and BQAutoEval 1.0.4 working very well. But where are the Fuses?  Maybe in the Register Map page of the BQAutoEval Tool.  In that page I can see unlock, but no additional information.  Also, my PC interfaces with the USB2ANY Board through USB Cable, then USB2ANY is connected to BQ79600EVM through SPI, then BQ79600EVM to our BMS through Daisy.  In the BQ AutoEval Tool, page Register MAP, I see SPI_FIFO_Unlock, then to lock i set all at 1? I see DEBUG_CTRL_UNLOCK too.  If you could help to lock my Values forever in the OTP Registers, so that after re-powering the BQ my Values remain intact.

Thanks in Advance,


  • Hi Ayadi,

    When the power supply is reconnected, the BQ79616 must receive a wake ping (or tone if using stacked devices). The ping/tone will reset the device's registers. To save the OTP registers, the device can be put to sleep and then turned to active, but that still requires the power supply to be connected at all times. In terms of what the TI-Techniker was saying, I do not know of any required fuses in the circuitry or registers so it may be worth following up with them if possible.


    David Ray

  • Thanks David,

    then as I thought, the BQ does not hold the written Values in its OTP Registers after re-power.  

    I will program the µC to re-write the Values in the OTP Registers upon new Start occurs.

    bye, Ayadi