Buck-boost control circuit of LED (Light Emitting Diode) lamp

Abstract

The invention discloses a buck-boost control circuit of an LED (Light Emitting Diode) lamp, which has the outstanding advantages of wide output voltage range, good constant current characteristic, high efficiency, small size, simple circuit, low cost, high reliability and so on; the control circuit comprises a direct current power supply, an LED, a pulse width modulating circuit, a switching tube, an inductance coil with a magnetic core, an auxiliary coil and an output diode, wherein a control electrode of the switching tube is connected with the pulse width modulating circuit; an output electrode of the switching tube is connected with a current sampling resistor; an input electrode of the switching tube is connected to a direct current power supply by the inductance coil; an anode of the output diode is connected with one end of the inductance coil; a cathode of the inductance coil is connected with an anode of the LED; a cathode of the LED is connected with the other end of the inductance coil; the auxiliary coil is connected with a voltage feedback end FB of the pulse width modulating circuit; and a CS of the pulse width modulating circuit is connected with the current sampling resistor; a starting end Vin of the pulse width modulating circuit is connected with the direct current power supply by a resistor.

Description

technical field [0001] The invention relates to a switching power supply circuit, in particular to a voltage-boosting control circuit for a switching power supply of an LED lamp. Background technique [0002] In LED (Light Emitting Diode) lamps, since the LED conduction voltage drop varies and varies with temperature, in order to keep the LED's luminous brightness constant and color temperature consistent, the driving power supply must adapt to this difference and change. In the prior art, a buck or boost constant current drive circuit is usually used. However, when the output voltage is close to the input voltage, since the voltage drop of the LED will change with the temperature, the output voltage of the driving power supply may be greater than the input voltage, or may be less than the input voltage. Therefore, for both step-down and step-up None of the circuit topologies satisfies its requirements well. The publication date is May 09, 2012, and the patent document wit...

AI Technical Summary

Problems solved by technology

The disadvantages of this technical solution are that the flyback power supply with the original secondary side structure is not suitable for high voltage output, and the second is that there are many components used, the circuit is complicated, and the volume of the power supply device is too large, which affects the reliability and reliability of the power supply device. It is easy to install, and the constant voltage control does not conform to the working characteristics of LED, which will affect the luminous effect of LED

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