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PMP9068: Can this be changed to a 5V Output?

Part Number: PMP9068

The PMP9068 is setup for 3.3V @ 900mA.  Can this circuit be modified for 5V 600mA?

  • Patrick,

    Yes, it can, but it will require a new transformer and other components changes.

    Are you going to use the secondary side regulation or primary side regulation?  PSR requires a transformer with good coupling between the bias and secondary windings.

    For SSR, PMP11271 is a similar design with a 5V output.

    https://www.ti.com/tool/PMP11271?keyMatch=&tisearch=search-everything&usecase=refdesign

    We also have the TPS23758 with PSR and integrated primary side FET.

    https://www.ti.com/product/TPS23758?keyMatch=TPS23758&tisearch=search-everything&usecase=GPN

    Thanks,

    David

  • Thank you for your response.  I had planned to do secondary side regulation. 

     I had not seen the PMP11271, so will look at it.

    How can I reduce the output ripple on this TPS23753A designs?  The documentation for the PMP11271 is showing a ripple of  38.7mV.  I have the TPS23753AEVM-001, and can see similar (possibly higher) values. 

    Additionally in the TPS23753AEVM, I see a spike of what I’m assuming is the switching of the Q1 mosfet in the output waveform that is quite a bit larger as it repeats at 250khz.  How can I tamp this down?

     Thank you!

  • Patrick,

    You can add more capacitance to reduce the ripple, but it won't help much with the switching spikes.

    The most effective way to reduce the ripple and spikes is to add a second stage filter.  PMP20220 shows an example.

    https://www.ti.com/tool/PMP20220

    Keep the inductor value below 0.33uH to avoid resonances that could affect the control loop.  It can be modeled as an LC filter to select the required capacitance/attenuation.

    Also, make sure you have a very short ground lead on the scope probe to measure the ripple.  A probe tip ground adapter is best.

    Thanks,

    David