SLUSD66D September 2019 – February 2021 TPS92520-Q1
PRODUCTION DATA
A simple integral compensator is recommended to achieve stable operation across the wide operating range. The bode plot of the loop gain with different compensation capacitors is shown in Figure 8-2. The buck converter behaves as a single pole system with additional phase lag caused by the switching behavior. The gain and phase margin is then determined by the choice of the switching frequency and is independent of other design parameters. TI recommends a 1-nF to 10-nF capacitor to achieve bandwidth between 4 kHz and 40 kHz. The choice of compensation capacitor impacts the transient response, the shunt FET dimming behavior and PWM dimming performance. A larger compensation capacitor (lower bandwidth) is recommended to limit the LED current overshoot on the rising edge of internal or external PWM signal. A smaller compensation capacitor (higher bandwidth) is recommend to improve shunt FET dimming response.
L = 68 µH, fSW = 437 kHz |