TPS650250: EN_DCDC1 logic low could not shut down VDCDC1 .

Hi Gabriel,

Can you provide a clearer image of the schematic? The picture attached in the word doc. that is a photo of a screen is not clear to me. Is the part of your schematic outlined in red populated or not?

Best,
Emily

Dear Emily

fyi .

the part of your schematic outlined means that we have removed that circuit and we test that VINDCDC1 still have 3.3V output.

And  we do cross experiment , the failure phenonen still exit .

Hi Gabriel,

Can you provide a scope shot showing the EN_DCDC1 pin going low and the output of DCDC1 staying high?

Best regards,

Layne J

Dear Expert

Yellow is DCDC1 ,Blue is EN_DCDC1 . And we change annother IC ,this  failure phenonen still exit ..

Hi Gabriel,

Is DCDC1 loaded during this time? Does the output of DCDC1 decay over time? Was the above scope shot for the EN_DCDC1 signal taken at the EN_DCDC1 pin or somewhere else on that net?

Best regards,

Layne J

Dear  Layne

1.Is DCDC1 loaded during this time?

We both test loaded and without load ,it's still have output.

2.Does the output of DCDC1 decay over time?

 DCDC1 is always has output.

3.Was the above scope shot for the EN_DCDC1 signal taken at the EN_DCDC1 pin or somewhere else on that net?

 It's EN_DCDC1 pin.

Hi Gabriel,

I am currently looking in to this issue and will be able to provide an update tomorrow. Thank you for your patience.

Best regards,

Layne J

Hi Gabriel,

Can you try removing all of the circuitry connected to EN_DCDC1 and then pulling that pin low by soldering a wire from the EN_DCDC1 side of the R35 pads and seeing if that will disable the regulator?

Are you seeing this issue with any of the other regulators?

Best regards,

Layne J