SNVA866A February 2019 – January 2023 LM5155 , LM5155-Q1 , LM51551 , LM51551-Q1
The RCOMP resistor and CCOMP capacitor set a low frequency zero of the compensation network, providing a phase boost. Placement of this zero frequency largely impacts the transient response of the control loop. A good strategy to help ensure adequate phase margin is to place the zero at geometric mean of the crossover frequency (fCROSS) and the low frequency pole of the modulator. Equation 31 places the low frequency zero of error amplifier a the geometric mean of fCROSS and low frequency pole of the plant (ωP_LF).
where
For this design CCOMP is selected to be 220 nF to help ensure extra phase margin.