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TPS630250: Not sustaining 3.3V output

Kennedy Jackson
Prodigy 10 points
Part Number: TPS630250

Hello,

My name is Kennedy and I am a student working on a school project. I had a question about the operational capabilities of the TPS630250 converter. I am supplying about 3.72V from a Lithium-Ion battery to the TPS630250RNCR converter designed as shown below to get 3.3V output. I have been able to get 3.3V at one point. However, the voltage is not sustaining itself and is dropping to about 100mV. The converter also may have seemed to short itself out under these conditions, but I have no idea what caused the internal damage. If anyone could take a look into this or provide any insight I would greatly appreciate your help. (Please note pin 10 was a blue wire connection and is not in the original PCB design, but is connected to power on the actual PCB)

Regards,

Kennedy

  • 0
    TI__Mastermind 19750 points

    Hi  Kennedy,

    i think you must re-design your layout. please take the layout example in D/S as ref.

    Regards

    Tao

  • 0 in reply to Tao Zhang
    Prodigy 10 points

    Hi Tao,

    Thanks for your response. Unfortunately, with the current state of our project and budget constraints, we don't have the option to re-design our PCB. We're using a 2-layer PCB with components on the top and bottom layer. I have been able to get 3.3V output and I included a picture of the waveform below, but somehow the chip shorted itself during testing and the resistance of the chip dropped to 3ohms.  

    This waveform was taken when the TPS voltage output was at 3.3V. Not sure about the ripple in the middle of the waveform, but besides the layout do you have any other recommendations?

    Thanks,

    Kennedy

  • 0 in reply to Kennedy Jackson
    TI__Mastermind 19750 points

    Hi  Kennedy,

    the layout is really bad.and i think that's why your chip damaged. 

    the traces of power stage are really small and with large parastic indutor which will cause some high spike voltage. and these spikes may damage your chips.

    Regards

    Tao