Power circuit and diming control method for led lighting device

A power circuit for a light emitting diode (LED) lighting device including an alternative current (AC) power supply, a dimmer, a transformer and a dimming control circuit, wherein the dimming control circuit includes:

• a filtering unit configured to filter a voltage signal outputted from the transformer and output the filtered voltage signal;
• a rectifying unit configured to:
• receive the signal outputted from the filtering unit;
• rectify the signal to a direct current (DC) signal;
• and
• output the DC signal;
• a boost converter unit configured to receive the DC signal outputted from the rectifying unit and boost the received DC voltage to a needed DC voltage;
• a voltage feedback control circuit unit configured to control the DC voltage boosted by the boost converter unit;
• a buck converter unit configured to convert the DC voltage boosted by the boost converter unit to the voltage and current needed by the LED lighting device;
• and
• a digital control unit, which is respectively connected to the boost converter unit, the voltage feedback control circuit unit and the buck converter unit, configured to automatically adjust current strength needed by the buck converter unit based on the voltage at a certain point boosted by the boost converter unit and the voltage ripple, such that input power and output power are dynamically balanced and light flicker does not appear.