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TPS22953: broken eval board & recommendation for power mux

Part Number: TPS22953
Other Parts Discussed in Thread: TPS22976EVM,

Hi - I received a TPS22953EVM today. Weirdly, the enable of the DSQ part doesn't work. ie. regardless of the position of jumper on JP2, power is fed from the input to the output. The DQC part works fine, as expected. This is especially odd since I had a problem with a TPS22976EVM (elsewhere in the forum) just a week or so back. I'm sure I'm not doing anything wrong because all I've done is hook up 4V to the input and measure the output!

Anyway, here's the design I'm trying to evaluate. It's for a USB peripheral. 5VSw is the output that powers everything else. Normally it will operate with 5V0_USB but if 5V0 is present (becuase someone's plugged in an external supply) - it will use that in preference. 5VSource indicates which supply is being used. Can you see any problems?

Many thanks,


  • Hi Jon,

    Sorry to hear about the EVMs. As I had mentioned for the TPS22976EVM, we do test all of our boards before shipping, so I'm not sure why the ones you received did not work as expected.

    Regarding your TPS22953 configuration, it should work as you have hooked it up. I see you modeled figure 63 in the datasheet to come up with your power muxing solution. If you want more information on expected performance, we have additional waveforms in the app note below. This app note also shows additional solutions for you to consider.


    Alek Kaknevicius

  • FYI: I just received a replacement TPS22953EVM via Digikey. What do you know? It is also faulty, but with a different fault this time.

    Literally, all I've done is unpackage it and apply 3.5V to J1. It drew 230mA so I turned it off immediately. I measured the input resistance on J1 as 150R to GND. The previous faulty one did not have this fault but was permanently on, despite changes to the EN pin. 

    Clearly, whatever you say about testing, there is a serious issue with the assembly of these eval boards. Can I send these two to you for failure analysis?

  • Hi Jon,

    I've taken a look at past data for this EVM, and it looks like we haven't had any issues from any customers up to this point. To help resolve your issue, please email me directly at and we can discuss next steps here.


    Alek Kaknevicius