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TPS40400: tps40400 no output

Part Number: TPS40400

I designed a tps40400. 

But there is no output. Circuit is same with your webench.

BP3, BP6,VDD pin voltage is normal. There is no switching signal.

GUI status error is Vout OVF.

I don't know what's problem.


    VOUT OVF is an output Over Voltage Fault, which is declared when the Feedback Pin rises above the reference point enough to trigger the OV comparator.

    The response to the fault condition is defined by the VOUT_OV_FAULT_RESPONSE (Comand Code 41h) which is defaulted to shutdown and do not retry (b'000) so once an OV fault occurs, the converter will remain off until disabled and enabled, then it will make 1 attempt to start-up.

    You can update the VOUT_OV_FAULT RESPONSE value to allow restart after a short time-out by setting VOUT_OV_FAULT_RESPONSE to 7Ch (Shutdown with Delay, retry without limit)  However, if it triggered an OV on the first start-up, it will likely trigger OV on repeated start-ups, so we should check out the failed start-up attempts before changing the fault response.

    First, update VOUT_SCALE_LOOP value to match the resistor divider that you have used for feedback.  VOUT_SCALE_LOOP = VFB / VDIFFO

    Second, update VOUT_OV_FAULT_LIMIT, VOUT_UV_FAULT_LIMIT and VOUT_COMMAND to your desired voltage.

    Third, review your compensation network between DIFFO, FB and COMP.

    Once you have all of that complete, you can update VOUT_OV_FAULT_RESPONSE, try to start-up and record the VOUT and FB voltages during the start-up attempt on an oscilloscope so that we can review them if the output triggers an OVF shutdown again.

    If you can share the schematic from your WeBench design, that would be very helpful.

  • Sorry, Peter

    I resolved problem. There is a mistake at PCB

    Thanks, Peter


    I am very glad to hear that you were able to solve your issue, glad we could help.   I am closing this thread, if you have any additional questions, please start a new thread.