Analysis of three common LED dimmable power supply



Analysis of three common LED dimmable power supply
Date: 2020-04-15 11:29:12Pageviews: 340

1. LED Triac dimmable power supply
Triac dimmable power supply has been applied in the dimming mode of incandescent lamps and energy-saving lamps earlier, and it is also the most widely used dimmable mode in LED dimming. It works by passing the input voltage waveform through the conduction angle tangent wave to produce a tangential output voltage waveform. By applying the principle of tangent, the effective value of the output voltage can be reduced, so as to reduce the power of ordinary load (resistive load). The advantage of Triac dimming is high efficiency and stable performance.
2. LED 0/1-10v dimmable power supply
Power supply design with a control chip, 0 to 10 v dimmer, by 0-10 v voltage change, change the power supply output current, drop light. For example: when the 0 to 10 v dimmer modulation to 0 v, the current drop to zero, the lamp brightness is closed (a switch). When the 0 to 10 v dimmer up 10 v, the largest output current also will reach 100% of the output power. The brightness will be 100% (output voltage is the same).
1-10 v dimmer principle: as mentioned, just 1-10 v dimmer is: when the resistance dimmers adjust to minimum 1 v, the change of the output current is 10%, such as to 10 v (up), the output current will be 100% of the output power, brightness will be 100% (output voltage is the same). Note: there is no switch function, 1-10 v lamps can not be transferred to the lowest close!
3. PWM dimmable power supply
Digital dimming, also known as PWM dimming, changes the conduction time of positive current by turning on and off the LED by PWM wave to achieve the effect of brightness adjustment. The method is based on the characteristic that the human eye is not sensitive enough to the brightness flicker to make the load LED light and dark.
If the frequency of light and dark exceeds 100Hz, the human eye sees the average brightness, not the LED flashing.PWM adjusts the brightness by adjusting the proportion of light and dark time. In a PWM cycle, the perceived brightness is a cumulative process, because the human eye flickers to the light within 100Hz. In other words, the greater the proportion of light time in the whole cycle, the brighter the human eye feels.However, for some high-frequency sampling devices, such as high-frequency sampling camera, the image of dark LED may be selected when sampling. Therefore, this paper combines analog and digital, and designs the driving circuit of LED.




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