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UCC28950 and other Phase-Shifted Full-Bridge Controllers Frequency Output Question

Zachary Beran
Prodigy 20 points
Other Parts Discussed in Thread: UCC28950, UCD3138

Background:

Building an isolated dc/dc converter that takes ~650 VDC in and spits out 200 VDC.

We're using the classic full bridge converter topology due to the power requirements. (>2kW)

Wanting to use a phase-shifted voltage mode control setup for the system.

Target switching frequency on the IGBTs we will be using is 25-30 kHz.

Looking at the UCC28950 but noticed that minimum switching frequency is 50 kHz.

I want to insure that I am interpreting the data sheet questions correctly and if so, does TI have another full-bridge controller capable of dealing with a 25-30 kHz switching frequency or if there is a way of getting the UCC28950 to meet our needs.

Thanks!

  • 0
    Genius 3295 points
    Hello Zachary,

    If it were me, I would get a chip and test it. The clocks are usually just RC timers. So I don't see what could keep you from running it at 25 KHz. The resistor does start to get pretty big at that frequency. So maybe you reach the leakage current limit inside the chip and the higher resistor value doesn't have any more affect on the charge up time.

    If it turns out you can't use the UCC28950, there are alternatives:

    You can use the C2000 delphino 28x series DSP to build a low frequency, high power converter. They are more pricey than the UC series. The UCD3138 is another powerful digital power supply controller that has phase control and is pretty cheap and you can run those down to very low frequency. If you don't have the resources for an embedded design, you can always use a discrete solution.
  • 0 in reply to Chuck Sampson
    Prodigy 20 points

    Chuck:

    Thank you for the response, I will look into the UCC28950 frequency programming and see if I can just run it down lower.