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Original question:

TPS25751: PD issue

BQ25792: 5V to 15V rising time

Jeff YANG
Mastermind 7865 points
Part Number: BQ25792
Other Parts Discussed in Thread: TPS25751,

Tool/software:

Hi,

we have doing the IEC62680 with BQ25792 + TPS25751,

There is issue about 5V to 15V rising slew rate is too fast, the dV/dt need <  30 mV/us.

Except set 2 step rising (ex. set 5V -> 9V-> 15V). Any other way to set smaller dV/dt to make sure <  30 mV/us? thanks!

  • 0
    TI__Mastermind 34466 points

    Hi Jeff, 

    TPS25751 does not have the capability to control BQ25792 slew rate, however you may be able to add additional capacitance on PPHV or system side (BQ25792) to reduce the slew rate to meet PD spec (30mV/us). 

    Forwarding this thread to the BQ team for their input. 

    Thanks and Regards,

    Raymond Lin

  • +1 in reply to Raymond Lin
    TI__Guru**** 166626 points

    Hi Jeff,

    In reverse mode, the BQ25792 startup/rise time is not directly controllable.  Indirectly, if the load is purely capacitive, the chargers IOTG current limit can be lowered so that IOTG=(CPMID+CVBUS) x dv/dt.  After the charger reaches OTG/reverse/source voltage regulation, IOTG must be increased higher than the expected dc load current.

    Regards,

    Jeff