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TPS74401: TPS74401

MaWü
Prodigy 220 points
Part Number: TPS74401

Hi there,

For validation I need to adjust the feedback voltage divider (R1) in small steps (Vout +- 5…10%) with a mechanical rotary switch resp. different given resistors (matrix) when no load is connected.

Would you recommend to disable the TPS74401 before changing R1?

Regards MW

  • 0
    TI__Genius 16776 points

    Hi MW,

    A mechanical rotary switch has 2 different contact styles - shorting and non-shorting.

    Through the shorting contact, the new position is connected before the previous position is disconnected; this means that the new top resistor will be connected in parallel with the old configuration. That will effectively lower the R1 value and cause VOUT to drop before recovering. 

    With the non-shorting contact method, the switch opens the circuit before closing with the following circuit. Leaving the R1 value open will pull the FB low, which will cause VOUT to follow VIN.

    Disabling the device is a safer option, but it is up to you if the possible risks do not affect your application.

    Best, 

    Juliette