CN214755487U

CN214755487U - Overvoltage and undervoltage LED protection circuit

Info

Publication number: CN214755487U
Application number: CN202121258362.2U
Authority: CN
Inventors: 俞雅露; 陈佳平
Original assignee: Guyuan Photoelectric Technology Shanghai Co ltd
Current assignee: Guyuan Photoelectric Technology Shanghai Co ltd
Priority date: 2021-06-07
Filing date: 2021-06-07
Publication date: 2021-11-16
Anticipated expiration: 2031-06-07

Abstract

The utility model provides an LED protection circuit of excessive pressure under-voltage, including LED drive power supply, LED cluster parallel group, LED drive power supply gives two voltage comparator as reference voltage through the stable voltage of constant voltage module circuit output, reference voltage includes the reference voltage of excessive pressure and the reference voltage of under-voltage, a voltage sampling circuit samples LED drive power supply and gives two voltage comparator, two voltage comparator and electronic switch circuit are connected, electronic switch circuit concatenates between LED drive power supply and LED cluster parallel group, when voltage sampling circuit's voltage is greater than or is less than excessive pressure reference voltage or under-voltage reference voltage, two voltage comparator output control signal give electronic switch circuit, cut off LED drive power supply. The utility model has the advantages that, the utility model provides an components and parts in excessive pressure, the undervoltage LED protection circuit all are conventional device, easy purchase, and the circuit is simple, and low cost can realize LED undervoltage, overvoltage protection.

Description

Overvoltage and undervoltage LED protection circuit

Technical Field

The utility model relates to a be applied to LED voltage protection field, mainly relate to an LED protection circuit of excessive pressure under-voltage.

Background

LED rapid development, LED product are more and more in the market, and the market also promotes step by step to the performance requirement of LED product, and when avoiding connecing high voltage power supply or operating voltage anomaly because of artificial mistake, lead to LED circuit system to lose efficacy or burn out the power, at this moment just need set up voltage protection. At present, a special voltage protection IC is used for overvoltage protection, but the special voltage protection IC has higher cost and is not easy to purchase.

Disclosure of Invention

For solving the problem that existing equipment exists, the utility model provides an LED protection circuit of excessive pressure under-voltage, including LED drive power supply, LED cluster parallel group, LED drive power supply gives two voltage comparator as reference voltage through the stable voltage of constant voltage module circuit output, reference voltage includes the reference voltage of excessive pressure and under-voltage reference voltage, a voltage sampling circuit gives two voltage comparator to LED drive power supply sampling, two voltage comparator and electronic switch circuit are connected, electronic switch circuit concatenates between LED drive power supply and LED cluster parallel group, when voltage sampling circuit's voltage is greater than or is less than excessive pressure reference voltage or under-voltage reference voltage, two voltage comparator output control signal give electronic switch circuit, cut off LED drive power supply.

The electronic switch circuit is characterized in that a drain electrode of an MOS (metal oxide semiconductor) tube is connected with a negative electrode of an LED serial-parallel group, a positive electrode of the LED serial-parallel group is connected with a U + of a driving power supply, a source electrode of the MOS tube is connected with a U-of the driving power supply, a grid electrode of the MOS tube is connected with a collector electrode of a triode, an emitting electrode of the triode is connected with the U-of the driving power supply, and a base electrode of the triode is connected with a double-voltage comparator through a diode.

The utility model has the advantages that, the utility model provides an components and parts in excessive pressure, the undervoltage LED protection circuit all are conventional device, easy purchase, and the circuit is simple, and low cost can realize LED undervoltage, overvoltage protection.

Drawings

Fig. 1 is a block diagram of the present invention;

fig. 2 is a schematic circuit diagram of an embodiment of the present invention;

the reference numbers in the figures illustrate:

1-an LED driving power supply; 2-constant voltage module circuit; 3-dual voltage comparator; 4-a voltage sampling circuit; 5-an electronic switching circuit; and 6-parallel LED strings. U +, U-LED power positive and negative electrodes; CV-regulated voltage.

Detailed Description

Referring to fig. 1 and 2, an LED driving power supply U + outputs a stable voltage CV to a dual-voltage comparator LM1 through a voltage regulator D1 and a transistor Q1 of a constant-voltage module circuit 2 as a reference voltage, the reference voltage includes an overvoltage reference voltage and an undervoltage reference voltage, a voltage sampling circuit 4 divides UV + by resistors R5 and R6 to obtain a voltage, and sends the voltage to the dual-voltage comparator LM1, and the dual-voltage comparator LM1 is connected to an electronic switch circuit 5.

The electronic switch circuit 5 is connected with the cathode of the LED serial-parallel group 6 through the drain electrode of an MOS tube Q3, the anode of the LED serial-parallel group 6 is connected with the UV + of the driving power supply, the source electrode of the MOS tube Q3 is connected with the U- (ground) of the driving power supply, the grid electrode of the MOS tube Q3 is connected with the collector electrode of a triode Q2, the emitter electrode of the triode Q2 is connected with the U- (ground), and the base electrode of the triode Q2 is connected with the output of the double-voltage comparator LW1 through diodes D2 and D3.

When the voltage divided by the resistor R6 of the voltage sampling circuit 4 is greater than or less than the overvoltage reference voltage or the undervoltage reference voltage, the dual-voltage comparator LM1 outputs a high level, so that the diode D2 or D3 is turned on, the triode Q2 is turned on, the MOS transistor Q3 is turned off, and the LED driving power supply is cut off.

The undervoltage and overvoltage critical voltage hysteresis values can be adjusted through the arranged feedback resistors (R7 and R8) and pull-up resistors (R9, R10 and R11).

Setting overvoltage and undervoltage thresholds, calculating reference voltage dividing resistance ratios (R2, R3 and R4) according to the overvoltage and undervoltage thresholds, selecting proper resistance according to the resistance ratio, taking the reference voltage output by the reference voltage dividing resistances (R3 and R4) as overvoltage reference voltage of the double-voltage comparator, and taking the reference voltage output by the reference voltage dividing resistance R4 as undervoltage reference voltage of the double-voltage comparator; the sampling resistors (R5 and R6) divide voltage, and R6 outputs voltage as sampling voltage of the dual-voltage comparator; when the sampling voltage is lower than the undervoltage threshold value, a pin 7 of the dual-voltage comparator LM1 outputs a high level, the diode D3 and the triode Q2 are conducted, the MOS tube Q3 is cut off, and the LED series-parallel group is cut off; when the sampling voltage is higher than the overvoltage threshold value, a pin 1 of the dual-voltage comparator LM1 outputs a high level, the diode D2 and the triode Q2 are conducted, the MOS tube Q3 is cut off, and the LED strings are connected in parallel to turn off the power supply.

The LED serial-parallel group 6 is composed of a plurality of LED serial-parallel. When the input power supply voltage is in the normal fluctuation range, the LED serial-parallel group 6 operates normally.

Claims

1. The LED protection circuit is characterized in that the LED driving power supply outputs stable voltage to a double-voltage comparator as reference voltage through a constant voltage module circuit, the reference voltage comprises overvoltage reference voltage and undervoltage reference voltage, a voltage sampling circuit samples the LED driving power supply and sends the LED driving power supply to the double-voltage comparator, the double-voltage comparator is connected with an electronic switch circuit, the electronic switch circuit is connected between the LED driving power supply and the LED serial-parallel group in series, and when the voltage of the voltage sampling circuit is greater than or less than the overvoltage reference voltage or the undervoltage reference voltage, the double-voltage comparator outputs control signals to the electronic switch circuit to cut off the LED driving power supply.

2. The protection circuit of claim 1, wherein the electronic switching circuit is connected to the cathodes of the parallel-connected LED strings by a drain of an MOS transistor, the anodes of the parallel-connected LED strings are connected to U + of the driving power supply, the source of the MOS transistor is connected to U-of the driving power supply, the gate of the MOS transistor is connected to the collector of the triode, the emitter of the triode is connected to U-, and the base of the triode is connected to the dual voltage comparator through a diode.