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TPS25751: TPS25751's battery charger's configuration for BQ25723

Part Number: TPS25751
Other Parts Discussed in Thread: BQ25713, BQ25731, , BQ25723

Tool/software:

Hi,

In the previous related post, i thought the issue had been resolved by changed battery charger configuration from BQ25713 to BQ25731 in the TPS25751's config patch generated by  the GUI tool.

0308_json.zip

Unfortunately, i run into a new issue, the PD kept enabling OTG and disabling OTG, using logic analyzer to see what happened: found PD controller keep cycling doing I2C write to charger:

OTG voltage: 5000mV or 5144mV; OTG current: 1750mA or 450mA; Enable-disable-enable-disable-enable.... OTG mode.(see below decoding file)

 decoder--250310-BQ25731.csv

Try to remove the I2C connection between PD controller and charger, it can work normally.

Could you give some guidance what's happening in PD controller for the cycling and why there is 2x OTG parameters:  5000mV / 1750mA  &  5144mV / 450mA, why OTG current parameter is not 3000mA as defined in source PDO? (as confirmed, the BQ25723 and BQ25731's OTG register is same)

Thanks in advance!

  • Hi Zong, 

    Thank you for reaching out!

    It seems that the device is issuing a hard reset which is why you are observing the cycling behavior. During a hard reset, the PD disables OTG mode. 

    1- What is the value of the sense resistors on the BQ side?

    2-Are you using a PD + BQ EVM setup or is this on a custom board? 

    3- What sink device is being used in this test?

    Best Regards, 

    Aya Khedr

  • Hi Aya,

    Replay as below.

    1- What is the value of the sense resistors on the BQ side?

    ---Both Rac & Rsr are 10mOhm. 

    2-Are you using a PD + BQ EVM setup or is this on a custom board? 

    ---On a custom board, TPS25751D pairing with BQ25723.

    3- What sink device is being used in this test?

    --Tried different brands mobile phone and wireless chargers in hand.

    Best regards and have a good day!

  • Hi Zong, 

    Do you see this cycling behavior with all devices? Do you have PD logs of this behavior?

    Best Regards, 

    Aya Khedr