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TPS2557-Q1: TPS2557-Q1, LM25088

Tapan Pattnayak
Prodigy 40 points
Part Number: TPS2557-Q1

Tool/software:

TPS2557-Q1.

I have  a load switch which provides current to a System on a module (5V) whcih on boot time can take 2.5A. But drops to 1A after boot up.  I have added a 21K ohm as the Ilimit resistor to this load switch. 

At the output of load switch I have 4 22uF  cap. The caps are rated >10V.  

However after multiple run I see either the load switch or the cap gets damaged. Question

1. Why >10V comes at the OP of  load switch. If so other component on the 5V output line could have been damaged. Why they are not damaged but the load switch only. 

2. The fact that one of the op cap get damaged before the load switch points to me that the noise >10V is traveling from output to input ?

  • 0
    TI__Mastermind 29770 points

    Hiu Tapan,

    What are the voltage ratings of the Capacitors?

    Can you capture a scope plot of 5V_FUSE_OUT, STEM_EN, and VDD_SMARC so that I can understand what is happening in the system?

    Thanks,

    Chuck

  • 0 in reply to Chuck Branch
    Prodigy 40 points

    More observations

    1. Today the system stopped again. On observing the input , it was found to be proper but op was  not there. Toggling the EN pin made the load switch generates output.

    We have not put any cap on the En pin. The Enable pin is toggled from a Micro controller during boot up. The fault pin is not read back.

    There is also another problem. On disabling the EN pin the OP stays high for quite a time and takes about a minute and stays at around 2-3 V. There seems to be no quick discharge.

    All the signals rise time on EN= 10ns and Vin =1 ms  Vout=1ms when it is functioning properly.

  • 0 in reply to Tapan Pattnayak
    TI__Mastermind 29770 points

    Tapan,

    I cannot assist in debugging this issue without seeing the signals.

    The TPS2557-Q1 does not provide a discharge when disabled, so the long discharge time is likely caused be the load of a out on the output.

    Regards,

    Chuck