It is difficult to achieve accurate light output control by adjusting forward current. LED is a diode that can be switched on and off quickly. It can switch at a speed of more than microseconds. It is unmatched by any LED light-emitting device. Therefore, as long as the power supply is changed into a pulse constant current source, by changing the pulse width of the method, you can change LED brightness. This method is called pulse width modulation (PWM) dimming. If the pulse period is TPWM and the pulse width is ton, the working ratio D(or porosity ratio) is ton/ TPWM. The brightness of the LED can be changed by changing the working ratio of the constant current source pulse. Different brightness is suitable for different occasions, according to the need to choose the appropriate brightness. 0.32 inch CL3231AH LED Common-Cathode CC CL3231AH 7-Segment digit CL3231BH Display CL3231BH Common-Anode CA 0.32 inch 3312AS LED Common-Cathode CC 3312AS 7-Segment digit 3312BS Display 3312BS Common-Anode CA