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TPS63700: TPS63700 probabilistically failure to start

Part Number: TPS63700

Dear Expert ,

Good day !

Our customer use the TPS63700 with the reference design in the datasheet. Input 5V and output -5V.  Bom is same to recommendation .

But in sometimes(1/20~30),SW pin keeps disconnect state, no output voltage until  restart the 5V input. He test the SW pin, when it work successful, the pin keeps output regular square wave. otherwise in those failed case, output wave can not be detected.  the probabilistic is same with or without load . this picture is about SW pin out put when work successful.

Is the burr before square wave normal ?

When he take the C6 near COMP pin out, the probability of fail state obviously drop down .In those failed case ,if I use a tweezers connect FB pin to GND in a short time , then it will work again.

Could you provide any suggestions about how to fix it ?

BR,

Leon.liu

  • HI  Leon,

    i tried to reproduce your problem based on EVM, but i failed,  EVM works normally all the time.

    so could you help to capture waveforms during failed case?  Vin/SW/COMP/OUT in a picture is better.

    Regards

    Tao