Difference between PWM LED Power Supply vs CCR LED Power Supply

This page compares PWM (Pulse Width Modulation) LED Power Supply vs CCR (Constant Current Reduction) LED Power Supply and mentions difference between PWM LED Power Supply and CCR LED Power Supply.

Both PWM and CCR are techniques used for dimming the LEDs. The guide will help to select appropriate method for application of use. As we know LED has specification called rated current which is amount of current required to flow to achieve maximum light output.

PWM (Pulse Width Modulation) LED Power Supply

PWM Power Supply Waveform

In this method, current is switched at higher frequency between zero and rated current output. This refers to LED load is off or running at rated current.

The figure-1 depicts LED PWM power supply waveform. Here LED is ON 25% of time and OFF for remaining 75% of time. LED brightness is determined by ratio of ON time to OFF time.

CCR (Constant Current Reduction) LED Power Supply

CCR power supply waveform

In this method, current is flowing continuously at fixed amount for desired light level. Here amount of light output depends on current flowing through LED. Hence brightness of LED is controlled by varying LED current. The figure-2 depicts LED CCR power supply waveform. As shown dimming is reduced to 25% level. This method is also known as "Analog Dimming" technique.

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