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TPS65982EVM External Power

Gim Song
Intellectual 1120 points


Hi,

Can someone explain why there is voltage on "External Power" (J6_Pin2) on EVM when the jumper is removed and there is no 20V (Barrel Jack) connected to J4?

The EVM is programmed as SINK (UFP). I do not see any other connections of "External Power" except to DC_DC converters from the schematics.

Thanks.

Best regards,

Gim Song

  • 0
    TI__Expert 6430 points

    Hi Gim,

    Pin2 of J6 is connected to the external FETs and if they are on then you'll see VBUS coming to Pin2 of J6. I assume EVM is making a USB PD contract and using external FETs to pass the power and because of which you're seeing voltage on the Pin2 of J6.

    Thanks,

    Rahul 

  • 0 in reply to Rahul Sharma16
    TI__Intellectual 1120 points

    Hi Rahul,

    Sorry, I'm referring to J6_P1 for the question. Attached is the schematic capture of J6 where the jumper is not there (removed). Do you know why there is voltage seen at External Power J6_P1? There is no 20V barrel jack there on EVM which is programmed as SINK.

    On the bench, I used 2 TPS65982EVM for the following conditions.

    a) Source with 20V barrel present (Config ID0 - Docking system) and SINK (Config ID1 - Tablet/Ultrabook)

    Result: J6_P1 is measured 18.97V and J6_P2 is measured 19.5V. EVM is programmed to SINK for 20V @ 5A.

    b) Source with 20V barrel present (Config ID1 - Tablet/Ultrabook) and SINK (Config ID0 - Docking system)

    Result: J6_P1 is measured 4.51V and J6_P2 is measured 4.96V. EVM is programed to SINK 5V @ 0A (PP_EXT path should not turn on).

    This J6_P1 voltage is seen at J4 (Barrel Jack).

    Thanks.

    Best regards,

    Gim Song