DC/DC Converter Application Note
The LED High-speed Dimming Control
The LED brightness is set by the current through the LEDs, it can be controlled by the Duty of a PWM signal applied to the CE pin. The current through the LEDs can be calculated by the following formula.
ILED=Hduty x VFB / R1
Following product with high-speed dimming control can be used in the PWM signal range between 200Hz to 300kHz.
When controlling the LED brightness with a PWM signal of 20kHz or less; The variation of the inductor current might cause audible sounds, please use a PWM signal in the high frequency area to avoid this.