Switching power supply controller for constant current driving of LED by primary side control and method therefor

Abstract

The invention discloses a switching power supply controller for constant current driving of an LED by primary side control, a method for the constant current driving of the LED and a switching power supply formed by using the switching power supply controller. The switching power supply controller comprises an oscillator circuit, an input alternating current average value calculating circuit, a conduction time control circuit, a logic control circuit and a driving circuit. The controller controls the constant current driving of the LED by using a primary side control method to realize same output current and high power factor under the condition with controlled silicon dimming and high-low voltage input; and transformer isolation is directly used, so that the safety performance of the circuits is improved, a peripheral circuit is simple, the circuit cost is reduced, and the PCB (printed circuit board) distribution space is very small in favor of product miniaturization.

Description

technical field [0001] The invention relates to LED lighting technology, in particular to power factor adjustment (PFC), thyristor dimming, and primary-side LED constant current driving technology. Background technique [0002] As LED technology develops, the brightness and efficiency of LEDs continue to increase. LED lighting for daily households continues to develop, and has gradually become the mainstream of energy saving, emission reduction, and green lighting. [0003] The traditional AC power supply LED constant current drive circuit with power factor adjustment (PFC) function has two structures: isolated and non-isolated. There are two control structures in the isolation structure, one is two-level control, and the other is single-level control. Compared with the two-stage control, the single-stage control circuit is relatively simple and the cost is relatively low. The present invention is mainly aimed at the isolated single-stage control LED driving circuit. [0...

AI Technical Summary

Problems solved by technology

Since the general PFC (power factor adjustment) controller is specially used for boost mode control, the PFC performance of the circuit is not very ideal, especially when the input voltage is very high, the power factor drops

Due to the use of optocoupler feedback, an error amplifier needs to be added on the secondary side to sample the output current, and an optocoupler is also required to achieve isolation and transmit the output current signal to the input terminal. More components are required, and the circuit implementation is more complicated.

The PCB layout space is very large, which is not conducive to the development trend of product miniaturization, and the circuit cost is high

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