As far as the current domestic LED drive power design trends are concerned, products that use the capacitive step-down principle to complete the drive circuit design have gradually established a firm foothold in the market. The dimming LED power supply products of this design have better stability and lower cost.

In the triac LED drive power circuit made by the capacitive step-down principle, when a sinusoidal AC power is applied to the capacitor circuit, the charge on the two plates of the capacitor and the electric field between the plates are all functions of time.

Under normal circumstances, the main driving circuit of the LED power supply designed by the capacitor step-down principle will be composed of step-down capacitors, current limiting, rectification and filtering, and voltage stabilization shunt circuits.

The reason for the need for a voltage regulator shunt circuit is that the effective value of the current in the voltage step-down loop is stable and is not affected by changes in the load current. Therefore, there must be a shunt circuit in the voltage regulator circuit to respond to the load current. The size changes.