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BQ25890: DSEL signal polarity, all USB detect as "Unknown Adapter"

Jozef Augustín
Prodigy 60 points
Part Number: BQ25890

Hello

I have a problem with Input Source Type Detection with BQ25890. All USB (PC, USB charger, power supply with shorted D+/D- pins) is detected as Unknown Adapter.

I measured state of DSEL pin with oscilloscope and i think it has wrong polarity. 

DSEL pin description in Datasheet: 

Open-drain D+/D- multiplexer selection output. Connect the DSEL to a logic rail via 10-KΩ resistor. The pin is normally float and pull-up by external resistor. During Input Source Type Detection , the pin drives low to indicate the bq25890 D+/D- detection is in progress and needs to take control of D+, D- signals. When detection is completed, the pin keeps low when MaxCharge™ adapter is detected. The pin returns to float and pulls high by external resistor when other input source type is detected.

I measured during input source type detection high and then go back to low. (oscilloscope screenshot in attachment). 

My connection is the same as connection in EVM. Why the DSEL signal si inverted against the datasheet.

There is schematic in attachment. 

  • 0
    TI__Guru 57341 points
    Hi,

    Could you please share all the BQ25890 register values after the input detection is complete?

    Thanks,

    Ning.
    Please click "This Resolved my issue" button if this post answer your question.
  • 0 in reply to Ning T
    Prodigy 60 points

    Hi Ning.

    Here is register values after input detection is complete.

    Thank you

    Jozef

  • 0 in reply to Jozef Augustín
    TI__Guru 57341 points

    Jozef,

    I tried unknown adaptor on the EVM. It takes some time for DSEL to return to HIGH. Please refer to the waveform below.

    Thanks,

    Ning.

    Please click "This Resolved my issue" button if this post answer your question.

  • 0 in reply to Ning T
    Prodigy 60 points
    Hi Ning.
    Thank you for your measurement on EVM.
    In my prototype never return DSEL to HIGH. After 10 seconds, 1 minutes, 10 minutes, is still LOW.
    At your measurement input detection run when DSEL is in LOW.
    At my measurement input detection run when DESL is in HIGH.
    Why? I used the same wiring as the EVM.

    PS: When I force connect DSEL to the ground, the input detection is successful.

    thanks

    Jozef
  • 0 in reply to Jozef Augustín
    TI__Guru 57341 points
    Jozef,

    As described on the d/s about DSEL: DSEL pin is normally float and pull-up by external resistor. During Input Source Type Detection , the pin drives low to indicate the bq25890 D+/D- detection is in progress and needs to take control of D+, D- signals.

    It is highly recommended to get familiar with the BQ25890 charger operation by testing the BQ25890 EVM (www.ti.com/.../bq25890evm-664).

    Thanks,

    Ning.
    Please click "This Resolved my issue" button if this post answer your question.