Analog dimming by changing the LED high power light circuit current size of the dimming, the power supply voltage constant by changing the resistance value of R to change the current in the loop, so as to achieve the effect of changing the LED brightness. Many other analog dimming are using an extension of this method, its advantage is that the current can be continuous, but adjustable current range is often limited by the hardware few adjust stalls, for the light sensor sensitive high-precision lighting equipment. this method is not ideal.
Digital dimming, also known as PWM dimming by PWM wave to turn the LED high power light on and off to change the forward current conduction time in order to achieve the effect of brightness adjustment. The method is based on the human eye perceives brightness flicker less sensitive to the characteristics of the load led high bay light when dark. Bright and dark frequency of 100 Hz, the average brightness of the human eye can see, rather than the LED high power light flashes. PWM to adjust the brightness by adjusting the proportion of bright and dark time in a PWM cycle, because the human eye, flashes of light greater than 100 Hz, the perceived brightness is a cumulative process, ie, the brightest time in the share of the entire cycle The greater the proportion of, the human eye more bright. However, for high frequency sampling equipment, such as high-frequency sampling camera, sampling may be just taken to the LED is dark image. This article analog and digital combination of the design of the LED driver circuit.