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UCC25600 design testing

penchalaiah k
Intellectual 440 points
Other Parts Discussed in Thread: UCC25600

Hi 

I modified the Lr,Lm,T1,Cr, feedback & OC circuit in the reference design to get the 24V output.

After modification i am able to measure only 13.2V instead of the 24V output.

I am planning to disconnect the output feedback to the controller to validate the same in the EVM - LLC Resonant Half-Bridge Converter,300-W Evaluation Module. 

Planning to remove JP10 and C11 in the attachment.

Please let me know is it advisable to test like this.

Thanks

Pench8306.sluu361.pdf

  • 0
    TI__Expert 3095 points

    Hi Pench,

    I would not advise operating the EVM without C11 and JP10 fitted.

    It is difficult to operate this EVM fully open-loop since the bias winding voltage and secondary voltage rails are needed to provide control and power to the UCC25600.

    You have not mentioned the detail of the changes you made to the circuit so it is difficult to suggest why your output voltage is not what you expected. Observing the gate waveforms and resonant current on a scope should indicate if the problem is with the control or the power circuit. You need to understand if you are operating above or below the resonant frequency of the power stage.

    Hope this helps

    Joe Leisten

  • 0 in reply to Joe Leisten
    Intellectual 440 points

    Hi Joe Leisten,

     

    Now we are able to measure the output voltage as 24.7V with the feedback. only problem here is over voltage protection circuit needs to be modified in the EVM.

     

    I have the below query now:

     

    We modified the HPA341 EVM to our output requirement - 24.5V @ 17A by doing the following modifications:

    • Lr
    • Cr
    • Schottky diodes on the secondary side with heat sink
    • Transformer turns ratio and Lm
    • Feedback and OC circuit.

    We tested the modified reference board for the load currents from 0.5A to 6A and the measured output voltage is 24.7V & stable.

    Now we are planning to test the same modified reference board for the loads from 6A to 17A. 

    Please share your valuable inputs as per the reference board layout point of view is it advisable to test like this.

    Thanks

    Pench