LED open circuit guard circuit featuring low cost and high reliability

Abstract

The invention relates to an LED open circuit guard circuit featuring low cost and high reliability, comprising LEDs mutually connected in parallel and an output capacitor Cout, an electrical inductance L1 one end of which is connected with the cathode of the LEDs, a first MOS transistor M1, a drain electrode of which is connected with the other end of the electrical inductance L1, a source electrode of which is grounded by a first resistor R1; a free wheeling diode D1, the anode of which is connected with the drain electrode of the first MOS transistor M1, the cathode of which is connected with the anode of the LEDs, a control chip which comprises an enable pin en and an output port gate, cs; a transistor negative feedback control module which samples the output voltage at the two ends ofthe LEDs and generates output signals which can be output to the enable pin en of the control chip so as to control on-off of the first MOS transistor M1; wherein the anodes of the LEDs are connectedwith an electric power source Vin; the output port gate is connected to the grid of the first MOS transistor M1, and output ports cs are connected with the source electrode of the first MOS transistor M1.

Description

technical field [0001] The invention relates to an LED open-circuit protection circuit, more specifically, relates to a low-cost and high-reliability LED open-circuit protection circuit. Background technique [0002] figure 1 It is a schematic diagram of a traditional LED open circuit protection circuit. Such as figure 1 As shown, a decoupling capacitor Cin is connected between the power supply Vin and the ground; one end of the resistor R2 is connected to the power supply Vin, the other end is connected to the negative pole of the voltage regulator tube Z1, and the positive pole of the voltage regulator tube Z1 is connected to the positive input terminal of the optocoupler 12. The negative input terminal of the optocoupler 12 is connected to the negative pole of the LED, the negative pole of the capacitor Cout and one end of the inductor L1, the positive pole of the LED and the positive pole of the capacitor Cout are connected to the power supply Vin and the negative pole...

AI Technical Summary

Problems solved by technology

[0004] In the above-mentioned traditional open-circuit protection circuit, there are the following two disadvantages: first, when the circuit is open, the output voltage is detected by the Zener tube, and when the voltage rises above the rated voltage of the Zener tube, a current flows to the optocoupler, thereby turning the control chip 11 The en end of the circuit is pulled low, and the MOS transistor M1 is turned off accordingly. This detection method uses an optocoupler, so the cost is relatively high; less, and the use of TVS tubes instead of voltage regulator tubes will reduce the reliability of the protection circuit

[0005] It can be seen that the traditional LED open circuit protection circuit has high cost and low reliability

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