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PMP7668: Adjusting PMP7668 Design For 24V @ 200mA

Chad O'Brien
Prodigy 10 points
Part Number: PMP7668
Other Parts Discussed in Thread: UCC28722

Tool/software:

I have an application where I need roughly 24V @ 200mA with an input voltage ranging from 115VAC to 460VAC single phase. The design goal is for this to be low cost with a good expected life span and a smaller footprint.

In working through the design reference design PMP7668 steps, it looks like this shouldn't be much of an issue. The output inductor comes out to roughly the same value.

The new TOFF is calculated to be ~34.5uS which means the switching frequency becomes ~12.3kHz.

I will also have to adjust the output capacitor ESR and some of the input components. 

Is there anything I'm missing that doesn't make this change feasible? Or are there any other recommendations on parts or reference designs that I should review that may better suit my application?

Thank you!

  • 0
    TI__Intellectual 1125 points

    Hi, Chad O'Brien,

    This is a high voltage buck topology with UCC28722, owing to external bipolar, this solution could be pretty cheaper.

    owing to UCC28722 ground is referring to switching node, output voltage and input voltage sensing need to be considered. 

    Vout=4.05*(R1+R2)/R2. Vinbrown_in=Ivsl(run)(typical 220uA)*R1. So, if you keep the same brown in voltage, there is need to change R2=400kohm.

    Thanks.