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TPS65988: Table 8-7 error in datasheet: Boot Mode strapping for ADC1 input incorrect

david hilderman
Prodigy 180 points
Part Number: TPS65988

Tool/software:

On our 1st run of production we had 60 units fail out of 1000.  These units would sometimes start up and sometimes not. It turns out that table 8-7 is incorrect.  It states that ADCIN1 can be 0.60 to 1.00.  We had a 10k single pull up resistor to LDO_3V3.  These products do not have a battery so always start in dead battery mode.  When connecting to USB-C the EPROM would sometimes not load for a few seconds, sometime work properly and sometimes never start.  We had one unit that would never start up.  I added a 100k pull down to the 10k pull up and the problem is fixed.  The number highlighted in the table below should be 0.90 rather than 1.00

Unfortunately now all units need to be disassembled and have this 100k resistor added.

  • 0
    Prodigy 180 points

    Please confirm that this is in fact an issue- it seems to have fixed the problem, however if it could be something else please let me know.

  • 0 in reply to david hilderman
    TI__Mastermind 37855 points

    Hi David,

    That is not good to hear, I have not seen this particular issue in the past and agree that pulling to the LDO3V3 rail matches the DIV Max setting seen in the table.

    I am reaching out to experts internally to get feedback on your issue.

    Can you confirm the following:

    • LDO 3V3 has at least 5uF, max 25uF. (Nominal 10uF)
    • ADCIN is pulled up to the 10k resistor

    Are all 60 failures related to the ADCIN divider? You mentioned that you were able to fix the one unit that never started up by adding the 100k pull-down, was this the same for the rest?

    I will update you as I hear back from the team.

    Thanks and Regards,

    Chris

  • 0 in reply to Christopher Lim1
    TI__Mastermind 37855 points

    Hi David,

    I spoke with experts on the team and they confirmed this behavior has been seen in the past. Using the divider will fix the behavior. I will add an FAQ to the E2E site regarding this.

    Apologies for the issues here, I had not seen this issue in the past and was not familiar with it.

    Thanks and Regards,

    Chris