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TPS25750: When there is a battery present, the TPS25750 cannot communicate with the charger to establish a protocol, resulting in no power.

? ??
Prodigy 30 points
Part Number: TPS25750
Other Parts Discussed in Thread: TPS25751

Tool/software:


The local schematic design is shown in the figure. When the charger is not connected, the TPS25750 can communicate successfully with the charger and set the charging voltage to 20V. However, if the battery is connected first and then the charging cable is inserted, the TPS25750 has no input voltage. Could you please help me check what the problem is? Thank you.

  • 0
    TI__Mastermind 34076 points

    Hi, 

    ? ?? said:
    However, if the battery is connected first and then the charging cable is inserted, the TPS25750 has no input voltage.

    Can you elaborate what did you mean by "no input voltage"? Are you not seeing any voltage on TPS25750 VBUS or PPHV pin? What kind of charger are you connecting to TPS25750? Are you able to capture PD logs so we can see what (if any) CC traffic are available? 

  • 0 in reply to Raymond Lin
    Prodigy 30 points

    We don't have a PD protocol analyzer here, but we do have a USB protocol tester. Using the tester, we can determine if the rear end is communicating with a battery using the APPLE 2.4A protocol. If we plug and unplug the battery, it will automatically communicate with the PD3.0 protocol. However, if we don't disconnect the battery, the protocol will always remain APPLE 2.4A. But sometimes, the PD3.0 protocol is successfully communicated, is it because of interference from the PCB CC cable assembly?

  • 0 in reply to ? ??
    TI__Mastermind 34076 points

    Hi,

    Can you provide details on the "no input voltage" you mentioned previously? Are you not seeing voltage on VBUS, PPHV or both? 

    What kind of charger are you using in conjunction with TPS25751 or is this an external changer? 

    Thanks and Regards,
    Raymond Lin