PWM brightness adjustment circuit diagram

R1 and R2 are used to adjust +ULED to 29V. This is useful if there is an unexpected open circuit at the output. Without the voltage division of the above components, the output voltage may rise, causing device damage. Components C1 and R5 are used to stabilize the voltage feedback loop.

The best way to control the brightness of a white LED is to modulate the white LED current through a low-frequency PWM pulse. Using the low-frequency PWM pulse modulation method, the current of the white LED can be kept constant in amplitude according to changes in the duty cycle, and the wavelength of the light wave emitted by the white LED can remain unchanged throughout the entire adjustment range. The circuit that uses PWM to adjust brightness is shown in the figure.

Figure PWM brightness adjustment circuit