BCR420UFD / BCR421UFD

Document number: DS38588 Rev. 3 - 2

10 of 13

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January 2018

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BCR420UFD / BCR421UFD

PWM dimming can be achieved by driving the EN pin. Dimming is achieved by turning the LEDs ON and OFF for a portion of a single cycle. The

PWM signal can be provided by a micro-controller or analog circuitry; typical circuit is shown in Figure 3. Figure 4 is a typical response of LED

current vs. PWM duty cycle on the EN pin. PWM up to 25kHz with duty cycle of 0.5% (dimming range 200:1). This is above the audio band

minimizing audible power supply noise.

(Optional)

Figure 3 Application Circuits for LED Driver with PWM Dimming Functionality using BCR421U

Figure 4 Typical LED Current Response vs. PWM Duty Cycle for

25kHz PWM Frequency (Dimming Range 200:1)