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UCC28951: operation at 20KHz

Vincenzo Pizzolante
Mastermind 23521 points
Part Number: UCC28951
Other Parts Discussed in Thread: UC2875,

Tool/software:

hi,

we are replacing UC2875 with UCC28951 as unique option.

For our product, we absolutely need a controller that can operate at a switching frequency of 20 kHz, while the UCC28951 is recommended from 50KHz on.

my question is then: can the UCC28951 operate at 20KHz (RT >>100KOhm, accordingly to eq. 10 & 11)?

If no go, which ZVS with 4 outputs would you suggest?

thx a lot

Vincenzo

  • 0
    TI__Guru 73935 points

    Hello,

    Your inquiry is under review and I will get back to you shortly.

    Regards,

  • 0 in reply to Mike O'
    TI__Guru 73935 points

    Hello,

    Since the UCC28951 has zero voltage switching it was designed for high speed.  Since it is recommended to use above 50 kHz, I would not recommend using the device below 50 kHz.

    The UCC1875 uses an external capacitor to generate the external ramp and will allow you to design for lower frequencies.  If the customer really requires to operate at 20 kHz, they would be better off continuing to use the UCC1875.

    The benefit of phase shifted full bridge is zero voltage switching.  If they where to redesign for a higher frequency they could reduce there magnetic size reducing there power density, while maintaining the same efficiency.

    Regards,