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TPS23750: can't output 5v

user5900688
Prodigy 100 points
Part Number: TPS23750

I design a pd board by tps23750.

when i first connect to poe exchange ,it is can output 5v,but about 10 seconds later,the board can not output voltage.

test the voltage after electrolytic capacitorr ,it is 13.5v~19.5v .the tps23750 is very hot .  electrolytic capacitor is also little hot. i think some circuit is broken because it is ok at first. when i power off and on the poe switch.it is never work correctly.i tried change tps23750,it cannot work .so how to do?

  • 0
    TI__Mastermind 21320 points

    Hello,

    It sounds like one part got damaged during the power on stage. the TPS23750 has a thermal shutoff, and if it was hot then that limit was probably reached. It could be that a part broke during startup and caused a short. Or there is something else causing a short. I would check the other components since you replaced the IC, it is probably the IC that broke, or at least not only the IC. 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • 0 in reply to Michael Pahl
    Prodigy 100 points

  • 0 in reply to Michael Pahl
    Prodigy 100 points

    this is the err vedio,could help guess which part may broken?brige,res,cap,D4,Q2?

  • 0 in reply to user5900688
    TI__Mastermind 21320 points

    Hello,

    Can you test these components with a DMM to test if they are broken or not? Or try replacing them?

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • 0 in reply to Michael Pahl
    Prodigy 100 points

    I try to soldering another piece board with all new components,but still get the same result,the video as before,can you tell me why?

  • 0 in reply to user5900688
    TI__Mastermind 21320 points

    Hello,

    There is no visible breaking I can tell from the video. I cannot tell what components are broken if nothing visually happens. However, you could measure the components with a multi-meter to ensure the diodes are not broken, the FET is not damaged, the capacitors still have their values, and if there are any other shorts that should not be there. 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • 0 in reply to Michael Pahl
    TI__Mastermind 21320 points

     Hello,

    I have not heard from you in a few days. Do you have any update on this post? I want to make sure you are setup for success for your project, but if I do not hear from you I will close this thread. Feel free to post here or on a new E2E post to continue the conversation. Thank you 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • 0 in reply to Michael Pahl
    Prodigy 100 points

    I still can not find the error in my design,So i upload my sch and pcb.pls check some wrong in the sch?5153.switch_tps23750_5V_2.pdf

  • 0 in reply to user5900688
    TI__Mastermind 21320 points

    Hello,

    I reviewed the schematic and it looks very close to the EVM. The biggest difference was the FET. The FET used in the EVM has much lower capacitance than the FET used in this design. Other than that, it looks very similar. At this point it seems that is worth the time trying the FET used in the EVM. I would ensure all components are installed properly and with correct values. I would also double check the layout for any errors. 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • 0 in reply to Michael Pahl
    TI__Mastermind 21320 points

     Hello,

    I have not heard from you in a few days. Do you have any update on this post? I want to make sure you are setup for success for your project, but if I do not hear from you I will close this thread. Feel free to post here or on a new E2E post to continue the conversation. Thank you 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments