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TPS62840: Apply 3.3V to output?

Hans
Genius 12865 points
Part Number: TPS62840

Hello Team,

to program the MSP 3.3V will be connected to Vout while no input voltage connected as shown below. 

Is this a problem for TPS62840?

Thank you and best regards,

Hans

  • 0
    TI__Mastermind 18550 points

    Hello Hans,

    Thank you for using E2E,

    Hans said:

    to program the MSP 3.3V will be connected to Vout while no input voltage connected as shown below. 

    Is this a problem for TPS62840?

    This violates the datasheet recommendation, as the absolute maximum voltage at the SW pin depend on VIN. in you case Vin is 0V, so the maximum voltage at the SW pin should be 0.3V. I would recommend to use a diode in series.

    Thank you & regards,

    Moheddin.

  • 0 in reply to Moheddin Pasha Shaik
    TI__Genius 12865 points

    Hello Moheddin,

    I see, but what if the input is open and high impedance? In this case the voltage at SW cannot be higher than Vin, correct as no current flows, correct?

    Thank you and best regards, Hans

  • +1 in reply to Hans
    TI__Mastermind 18550 points

    Hello Hans,

    Hans said:
    what if the input is open and high impedance? In this case the voltage at SW cannot be higher than Vin, correct as no current flows, correct?

    If you ensure that, there is no current flowing from SW to VIN, then there should not be any problem.

    Instead you can also give the 3.3 V to both VOUT and VIN of the device keeping EN low, so that no current flows from SW to VIN.

    Thank you & regards,

    Moheddin.