High-efficiency LED lighting lamp linear driving circuit

Abstract

The invention discloses a high-efficiency LED lighting lamp linear driving circuit. The circuit comprises four parts, including an input protection circuit, a bridge type rectifier, a constant currentcontrol circuit and an overvoltage shutdown circuit, wherein the constant current control circuit is similar to a conventional linear driving circuit of an LED lighting fixture, the overvoltage shutdown circuit is connected in series between a negative terminal of the constant current control circuit and a negative terminal of the rectifier bridge and is composed of an input voltage sampling circuit, a reference power source, a comparator CP and an N-channel power switch tube, the circuit is generally applicable to multiple types of small and medium power LED light source lighting fixtures, and the circuit has advantages of high luminous efficiency, small temperature rise of a constant current control tube, small current surge current, wide input voltage range and the like.

Description

technical field [0001] The invention relates to the field of LED lighting, in particular to a linear drive circuit for LED lighting fixtures with high light efficiency. Background technique [0002] LED light source has the advantages of environmental protection, energy saving, long service life, low driving voltage, etc., and is recognized as the most promising lighting source in the 21st century. Due to the limitation of cost, lamp size, EMI interference and other factors, in recent years, small and medium power LED lighting lamps, such as bulb lamps, light pipes, ceiling lamps, spotlights, etc., have mostly adopted linear drive methods. The traditional LED linear drive circuit with capacitor filter is mainly composed of insurance tube FUSE, varistor VR, bridge rectifier BR, filter capacitor C, series LED chipset, LED working current sampling resistor Rs, current amplifier CA, reference voltage source V ref , adjustment tube Q and bias circuit, etc., as attached figure 2...

AI Technical Summary

Problems solved by technology

Although this type of linear drive circuit has the advantages of fewer components, low cost, and low EMI, it can only work in power supply occasions where the AC input voltage does not vary by more than 5%, such as LED chipsets selected according to 220V input voltage, when AC input Voltage U IN When it is too high, the adjustment tube Q drain-source voltage V DS It will also increase synchronously, which not only makes the power supply efficiency drop rapidly, but also increases the temperature of the adjustment tube Q, which will lead to overheating and damage of the adjustment tube Q in severe cases; on the other hand, when the input voltage U IN low, the bridge rectifier BR output voltage V IN Less than the series LED chipset operating voltage V F When the current flowing through the series LED chipset drops, serious stroboscopic phenomenon will appear

The third is that the filter capacitor C has a large capacity, and the surge current at the moment of power-on is large, and it may be necessary to connect a thermistor with low reliability in series in the AC input circuit.

Images