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TPS650944 BUCK3 switching frequency

Antony Lin
Genius 13480 points

Hi,

I see the spec of Fsw for BUCK3 is typically 1.7MHz, is there a maximum value.  Customer got result around 2.2MHz on their board as below.  Is it normal or not?

Antony

  • 0
    TI__Genius 17380 points

    Hi Antony,

    We expect some variation in the switching frequency for BUCK3, BUCK4, and BUCK5 since they are hysteretic converters and the frequency is not well controlled. There are several factors that can effect the switching frequency so I am not concerned that their frequency is a bit higher. We don't expect any issue running at 2.2 MHz.

    If they are concerned, they can check the output ripple on their board vs. the EVM. If their inductor is not as high performance, there will be a larger ripple which will cause the hysteretic converter to switch more frequently. It is not unstable, just switching more frequently.