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BQ24600: Stability

Anis MELKI
Prodigy 10 points
Part Number: BQ24600

Hi,

I have designed my charger with BQ24600RVAR with Lout = 3,9uH and Cout = 44uF

So LC output filter resonant frequency f0 will be 12,15kHz. You recommend to be between 16 to 28kHz

What kinf of problems will be if the stability frequency go to 12,15kHz ?

Thank you

  • 0
    TI__Mastermind 24075 points

    Hi Anis,

       BQ24600 is synchronous buck PWM converter, and uses a fixed-frequency voltage mode with a feed-forward control scheme. We have A type-III compensation network, which allows using ceramic capacitors at the output of the converter, and this allows us to size the zeros and poles such that the stable LC resonant frequency range is centered in the range of 16kHz to 28kHz as specified in the datasheet.

    I would say there is less risk if resonant frequency is lower than recommended LC resonant frequency range, as compared to if it was higher, but we do not validate for such conditions and cannot guarantee. You can validate solution to see if configuration is valid, or also reduce capacitance/increase inductance. You can refer to table 1. of the datasheet for common L and C values.