ZHCSGU1C September 2017 – October 2021 LM5150-Q1
PRODUCTION DATA
Based on Equation 18, CCOMP is calculated as follows:
By selecting CCOMP following Equation 34, the typical phase margin is set to 90⁰ and the loop response is overdamped. In this example, FZ_EA is placed at three times higher frequency than FLP to have lower phase margin but faster settling time (K2 = 3, target FZ_EA is 1.02 kHz). Recommended range of FZ_EA is from 1 × FLP to 4 × FLP (1 ≤ K2 ≤ 4). Practical crossover frequency will vary with K2 with a range of 0.5 × FCROSS to 1.0 × FCROSS.
A standard value of 33 nF is chosen for CCOMP.
RCOMP is selected to set the error amplifier zero at 1.02 kHz.
A standard value of 4.64 kΩ is chosen for RCOMP.
CHF is usually used to create a pole at high frequency (FP_EA) to cancel FZ_ESR. By using a small ESR capacitor, which can place FZ_ESR greater than 10 × FCROSS, the output capacitor ESR would not affect the loop stability. The maximum ESR, which does not affect the loop response, is calculated using Equation 38.