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Original question:

[FAQ] BQ76952: Common questions for OTP programming with the Bq769x2 Device Family

BQ76952: Using BQStudio to partially program OTP

Harry McNally
Intellectual 420 points
Part Number: BQ76952

Hi Matt

Extending your advice on thread: [FAQ] BQ76952: Common questions for OTP programming with the Bq8769x2 Device Family.

This may be obvious knowledge but I want to check before I proceed. I only want to program REG0 and REG1/2 in OTP to setup pullup supply for my I2C pullups. That is, I want to use 1 of my 8 signature values for partial OTP write: https://www.ti.com/lit/an/sluaa32a/sluaa32a.pdf '3 OTP Programming', Page 14.

I progress into OTP Program and have a check button to confirm I have 10 to 12 volts on BAT and VC16. The button below is "Program Data Memory to OTP Memory"

If I select that button, am I presented with a nested checkbox list of data sections and registers with each section so I can enable just the REG0 and REG1/2 register to write across into OTP ?

Can I also leave REG1 bits low and return later to write OTP for REG1 or is OTP a permanent write on a register by register basis ? 

Thank you
Harry   

  • 0
    Intellectual 420 points

    Apologies, My second question is answered in the TRM, 3.2 Configuration Using OTP or Registers, Page 14. I knew I had read this previously. Programming REG2 bits high and returning to program REG1 bits should be fine.

    Thank you
    Harry

  • 0 in reply to Harry McNally
    TI__Guru* 80963 points

    Hi Harry,

    I am not sure if I understand your question completely. When you send the OTP_WRITE command by clicking the button "Program Data Memory to OTP Memory", it will program all registers that have been modified. (There is no nested checkbox to select which registers should be programmed). So you should only change the registers you want to write to OTP before clicking this button. This will use one of the eight signatures. 

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Intellectual 420 points

    Thanks Matt

    I was over-thinking how much control I needed over what I wanted to write into the OTP.

    For my own clarity and for the thread;

    - I adjust the BAT+ and VC16 pin voltage to between 10 to 12V

    - I issue a RESET to the BQ76952 and it will reload all of the OTP data into RAM.

    - I can then adjust only the REG0 and REG2 regulator registers (in RAM) to provide 3.3V on the REG2 pin (in my case).

    - When I select the "Program Data Memory to OTP Memory" button this issues an OTP_WRITE and only those bits I have changed high will be irrevocably set high in the OTP.

    As you say, a new signature (checksum) is calculated and stored and consumes one of the 8 signature slots.

    Apologies for the caution in the earlier post. We have four prototype boards and mindful that the chip drought means consuming the BQ OTP means finding more parts. 

    All the best
    Harry