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TPS63030 has Vout without a Vin

Filippo Perati
Prodigy 10 points
Other Parts Discussed in Thread: TPS63030

Hello,

I'm using the TPS63030 to generate a 3.1V in a board powered by a couple of alkaline batteries. In order to save power I managed to isolate the Vin of the TPS63030 in order to be sure to switch off the 3.1V. I used a channel-P MOSFET and I switch it off and on through a signal from a microcontroller. When I switch off the MOSFET what happens is that the VIN value drop to 0V (as I expected) but the 3.3V value drop only to 0.66V and I don't understand why. When I measure it with the oscilloscope it starts to drop really slow and if I stop to measure it ramp up again to 0.66V. 

This is a very strange behaviour and I don't understand why. The board when it is all switched off absorbs 0.5mA while it should absorb no more than 0.05mA.

Attached the power supply schemaSCHEMA.pdf

  • 0
    TI__Guru**** 150610 points
    This does sound odd. Without a Vin (if it really 0V), the Vout must be coming from somewhere else on the PCB. Common leakage paths include through pull-up resistors, MCU I/O pins, etc. Anything connected to Vin.

    Just start measuring the voltage at various points in the circuit to see where the path is. The voltage divider on the batteries going to the MCU is where I would start.