TPS60241 output completely disconnected from supply when disabled?

Chad Murphy

Other Parts Discussed in Thread: TPS60241

I would like to feed a single load with to 5V supplies; one of which is produced by the TPS60241. I would like to avoid having diodes in series with the supplies. The second supply comes through a solid state switch and I was hoping by disabling the TPS60241 it would be able to handle having 5V applied to it without backfeeding or damaging the device.

over 14 years ago

0 Chris Glaser over 14 years ago

TI__Guru**** 150870 points

This should be possible but we'd like to check. We're having a board built up and hope to results in a few days.

0 Chris Glaser over 14 years ago

TI__Guru**** 150870 points

We tested the EVM in the lab with no input voltage and EN tied low. We then applied 5V at the output. The steady state current draw from the output was about 10uA.

However, some of the IC's nodes were partially charged from the output voltage, including the input. To charge these nodes, we noticed that the current from the output varied up to several hundred uA for a brief time before settling to 10uA.

So, nothing will be damaged on the IC but you will get some voltage on the input and you will lose some energy from this leakage current into the Vout pin of the IC.

0 Chad Murphy over 14 years ago in reply to Chris Glaser

Prodigy 170 points

In my design the input will always be connected to 3.3V and I will disable the IC when the "other" 5V supply is active and driving the shared output node. I am not concerned by the extra leakage current. In your tests you did not apply an input voltage - would you be able to apply 3.3V to the input and run your test again? I want to be sure the conduction path between input and output is high impedance under a powered (but disabled) condition.

0 Spandana Kocherlakota over 14 years ago in reply to Chris Glaser

TI__Intellectual 1595 points

I checked the device disabled with a 3.3V input and a 5V at the output. There is a 10uA leakage current at the output and the device works fine.

0 Chad Murphy over 14 years ago in reply to Spandana Kocherlakota

Prodigy 170 points

Excellent, thank you.

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TPS60241 output completely disconnected from supply when disabled?