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TPS552892-Q1: Switching frequency

Emma-Lirong Luo
Prodigy 20 points
Part Number: TPS552892-Q1

Tool/software:

According to the datasheet, the typical application see below link.

In our design, we choose (R5) Rsw=9.1K ohm, so base on the Equation 3 provided in the datasheet, Fsw=2.04MHz.But when I measure both side of the inductor, the frequency is about 994kHz, could you please explain why the tested frequency each side of the inductor is half of the calculation value? 

Waiting for your reply, thanks!

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  • 0
    TI__Mastermind 27760 points

    Hi Emma,

    Thanks for reaching out.

    Please notice that if both SW1 and SW2 are switching when Vin is close to Vout, it means the device is operating at Buck-boost mode, and the switching frequency of SW1 and SW2 will reduce to half what is set to achieve higher efficiency. So you could see both SW1 and SW2 are switching at about 1MHz which is normal phenomenon.

    BRs,

    Bryce