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Original question:

TPS65987D: How to control BQ25703 parameters via TPS65987D

TPS65987D: tells OTG bit to clear upon connection of a source and never comes back on...why?

chris woodhouse
Prodigy 100 points
Part Number: TPS65987D
Other Parts Discussed in Thread: BQ25703, TPS65987

I managed to get the TPS65987 talking to a BQ25703 and managed to get it to work using SLVAE18.pdf  as a sink and source, using the example in section 3 but with change: instead of sending 0x820E00 I sent 8A0E00. Worked fine for a while, then it stopped working as such.

I started again from fresh copying section 3 of the document, but now basically whenever I connect a source to the USB-C port, it sinks as expected but it clears the EN_OTG (0x35[4]) flag and does not re assert it upon detach of the source. I have tried re-asserting it upon detach but it doesn't work.

If the battery is full charged, can that cause an issue where OTG_ON_CHRGOK does not assert?

  • 0
    TI__Mastermind 32751 points

    I believe that the issue that you are seeing is caused by the fact that there is no way for the TPS65987 to handle charger termination when the battery is full.  You need to have a MCU in the system or use a charger that manages charge termination internally.