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LP87702-Q1: LP87702 input 5V，the twobucks can not work

user5670114
Prodigy 30 points
Part Number: LP87702-Q1
Other Parts Discussed in Thread: LP87702

 when LP87702 input is 5V，the two bucks have no output，why？

  LP87702：VANA=VIN1=VIN2=EN1=NRST=5V。

but VANA=VIN1=VIN2=EN1=NRST=4.2V，the two bucks can work。

  • 0
    TI__Intellectual 950 points

    Hi,

    LP87702 is OTP configurable 2 x BUCK and BOOST device. I assume that we are talking about LP87702DRHBRQ1 device?

    This OTP is for 3V3 VIN. When 4.3V VANA, then device Over Voltage Protection happen.

    If 5V VIN is needed, it will need custom OTP. Please contact to your local sales team to see if it is possible, thanks

    Tuomo

  • 0 in reply to Tuomo Alatalo
    Prodigy 30 points

    Hi,

      our device is LP87702DRHBRQ1.

      Now  5V VIN is needed, we try to program the regisster pg_good_level2, the VANA_THRESHOLD bit  is set 1, but the device can not work, the  outputs of the two bucks is 0V.

      

      Can we modify the registers to acheve the 5v VIN work mode?

    thanks

  • 0 in reply to user5670114
    TI__Intellectual 950 points

    Hi,

    Unfortunatelly it can't be changed by user. For the 5V VIN it will need separate custom OTP.

    VANA_THRESHOLD is not raise overvoltage limit and that is where you hit if VANA=4.3V or higher

    Tuomo

  • 0 in reply to Tuomo Alatalo
    Prodigy 30 points

    Hi,

       the message is known, thanks every much.