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WEBENCH® Tools/TPS54622: why the Compensation Components' value generated by WEBENCH do not conform to the datasheet equation 36

Part Number: TPS54622

Tool/software: WEBENCH® Design Tools

On page 36 of datasheet, Compensation Component Selection,equation 36 C4=Vout*Cout/(Iout*R4).Why the reference design genearted by WEBENCH Tools does not conform to it?

For example,Vin=10-14V,Vout=1.5V,Iout=1.6A.the WEBENCH design gives R4=1.02K,C4=100nF,Cout=44uF.

  • Hi Alan,

    We are looking into this, will feedback to you soon.



  • Hi Alan,

    It will be common to see slight differences between the values calculated in WEBENCH and those calculated with the datasheet equations. In general both will work. Typically the value from WEBENCH is more optimized because, in WEBENCH, the values are checked against a loop model. The datasheet equations on the other hand are simplified for easy calculation.

    With the values you shared, the Ccomp value calculated using the datasheet equations should be 40 nF. This isn't too far off from what WEBENCH recommends. Either value will work. The tradeoff is a 47 nF capacitor would allow shorter settling time in the transient response while the 100 nF capacitor would give more phase margin. The 47 nF gives shorter settling time because the settling time depends on the RC time constant at COMP.