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TPS56221: Small resistance between Vout and GND without power.

Motoyasu Hattori
Genius 9205 points
Part Number: TPS56221

Hi,

Is it possible to measure the resistance between Vout and GND without power on TPS56221 EVM?

My customer finished to assemble the board.  Before supplying input_power, he measured resistance between Vout and GND to confirm correct assembly, but resistance value is 5 ohm on his board.   He wants to know the possibility of small resistance even if board assembly is no issue.

Thanks and best regards,
M.HATTORI.

  • 0
    TI__Mastermind 19030 points

    Hattori-san,

    I am not sure how reliable the Vout to gnd measurement will be.   

    There are feedback resistors on the Vout to gnd, not an issue.

     But, the inductor is connected to the SW node which is a drain of the high side mosfet.   

    the mosfet has a diode (anti-parallel) on SW to VIN.    

    If the VIN is open and not connected to anything then the vout to gnd measurement is valid and you should measure feedback resistor values. 

    Measure vin to gnd impedance, if the vin to gnd is ~5 ohm, the vout to gnd is most likely ~5ohm.

    I confirmed on the evm.   

    No VIN connection    Vout to GND is the feedback resistor values.