For a buck LED driver, the compensation network defines the dynamic response of the current regulation loop. A smaller $C_{COMP}$ increases the theoretical loop bandwidth because the dominant compensation pole moves to a higher frequency. When $R_{COMP}$ is used in series with $C_{COMP}$ , the compensation zero is approximately:

Reducing $C_{COMP}$ shifts the dominant compensation pole to a higher frequency and increases the loop gain in the low-to-mid-frequency range. As a result, the current regulation loop can achieve a higher crossover frequency and a faster transient response, provided that sufficient phase margin is maintained. Figure 3-2 and Table 3-1 show the simulation results. During PWM dimming turn-on, this faster response helps the LED current reach its target value more quickly, thereby reducing the LED-current rising time. However, a smaller $C_{COMP}$ may increase the overshoot of LED current. Therefore, $C_{COMP}$ should be selected by balancing dimming response speed, loop stability, peak LED current.