In recent years, LED lamps have been widely used as lighting power sources instead of the traditional incandescent lamps. LED driving devices are commonly divided into traditional driving devices based on switching power supply, and linear driving devices, in which the linear driving devices are becoming more and more popular with their simple system structure and low costs. At the same time, dimmable LED lighting power applications are also increasingly used. SCR dimming is widely used as a common dimming method. Chinese patent CN202759647U discloses an LED control circuit and an LED lighting device with a high power factor, and recites an LED control circuit formed by a LED constant current driving circuit which is turned on sectionally and step-by step and capable of realizing a high power factor as well as a low harmonic distortion, and an SCR switch for realizing a dimming function. This is a common application on the market with the advantage of the high power factor and low harmonic distortion. However, as the LED lamp is turned on sectionally and step-by step, when the SCR switch has a large phase angle during the SCR dimming, the input voltage is not large enough to turn on all the LED lamps, the LED lamps are partially turned on, so the brightness of which is not uniform enough and the visual effect obtained is poor.
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