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BQ76952: Request for Guidance on Triggering OTP Memory Signature Permanent Fail on BQ76952

f gq
Prodigy 110 points
Part Number: BQ76952

Tool/software:

Dear TI Expert,

I hope this email finds you well.

I have recently conducted comprehensive tests aiming to trigger the "OTP Memory Signature Permanent Fail" (OTPF) on the BQ76952, using multiple methods including intentional conflicting OTP data writes, RAM modification without OTP_WRITE, OTP signature exhaustion (No_SIG), and even abrupt power interruptions during OTP writing. However, despite extensive attempts, none of these methods successfully triggered the OTPF protection state.

My tests clearly indicate that standard I2C/SPI commands provided by TI automatically recalculate and update the OTP signature with every write operation, effectively preventing any intentional mismatch between OTP data and signatures.

Could you please provide guidance or recommend specific TI tools or methodologies that can reliably and safely trigger an OTP Memory Signature Permanent Fail condition? Any suggestions or technical insights you could share would be greatly appreciated.

Thank you for your assistance.

Best regards,
DARLUU

  • 0
    TI__Genius 17795 points

    Hello DARLUU,

    f gq said:
    even abrupt power interruptions during OTP writing.

    When you do this, is the device still successfully loading the OTP settings? The permanent failure (PF) will usually show if the device fails to load in the new OTP settings after initial power up or reset on the internal OTP memory. If it succeeds in loading the correct settings during initial power up/reset, I would not expect the permanent failure to trigger. 

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 110 points

    Hello Alexis,

    Thank you for your prompt response.

    Regarding your question:

    "When you do this (abrupt power interruptions during OTP writing), is the device still successfully loading the OTP settings?"

    In my tests, after abruptly interrupting the power during the OTP_WRITE operation (approximately within a few hundred microseconds after sending the OTP_WRITE command), I observed that the device still successfully loads the original OTP settings upon power-up or reset. It seems the BQ76952 either completes the OTP write operation before the interruption takes effect or effectively prevents partial writes internally. Consequently, the loaded OTP settings remain consistent with the OTP signature, and no OTP Memory Signature Permanent Fail (OTPF) is triggered.

    I understand from your explanation that the OTPF condition specifically occurs when the device fails to correctly load OTP settings due to corrupted or mismatched data. Given these observations, could you please advise:

    • Is there a recommended method or a specific TI-supported tool to reliably trigger or simulate an OTP Memory Signature Permanent Fail condition for validation purposes?
    • Are there any internal self-test commands or production-level programming tools provided by TI to help verify the OTPF protection mechanism?

    Thank you very much for your continued support and clarification on this matter.

    Best Regards,
    DARLUU