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UCC12050: Increasing Output Capacitance

Kiron Sen
Prodigy 60 points
Part Number: UCC12050

Hi there,

I'm working on an inverter design that measures phase currents using AMC1303 ADCs, which require floating power supplies. To keep things simple, I'm considering exclusively using a DC/DC such as the UCC12050 instead combining a DC/DC with an LDO. I would like to reduce the output ripple of the UCC12050 to provide a cleaner power signal to the AMC1303 ADC, and hopefully improve ADC performance.

Page 19 of the datasheet states "the UCC12050 is optimized to run with an effective output capacitance of 5 µF to 20 µF."

How much can I increase the output capacitor beyond 20 µF? Will I risk destabilizing the internal voltage regulation loop?

Thanks!

  • 0
    TI__Mastermind 32835 points

    Hi Kiron,

    Large capacitor values seen by the VISO pin can result in voltage regulation issues due to the internal feedback and compensation. The maximum 20 uF guidance given in the UCC12050 data sheet is in place with enough margin to assure reliable stability and should be followed. It would be expected that higher capacitance might reduce the high frequency ripple but the lower frequency modulation shown in figures 29-36, will still determine the overall max and min and therefore the total peak-to peak may not improve as much as expected.

    Regards,

    Steve