Simple short circuit detection circuit and H-bridge two-line output LED dimming power supply

Abstract

The utility model discloses a simple short circuit detection circuit and an H-bridge two-wire output LED dimming power supply. The simple short circuit detection circuit comprises a rectifier bridge BD1, an optocoupler DU1, triodes Q5-Q8, a capacitor C1-2 and resistors R1-3. Through the circuit, the H bridge can be quickly protected, abnormal output work due to long-time short circuit is avoided, the H bridge circuit is also prevented from being damaged, meanwhile, an MCU circuit system can be reported to be subjected to next-step processing, and the circuit has the advantages of being small in device number, low in cost, quick in response and stable in performance.

Description

Technical Field

[0001] The utility model relates to the technical field of LED dimming drive power supplies and switching power supplies, in particular to a simple short-circuit detection circuit and an H-bridge two-wire output LED dimming power supply. Background Art

[0002] Currently, H-bridge two-wire output LED dimming drivers are widely used in the market, offering a variety of dimming and color temperature adjustment modes, achieving minimum brightness and smooth dimming. In H-bridge two-wire output dimming and color temperature adjustment drivers, the H-bridge circuit is primarily composed of four MOS transistors and other components. Only two output lines are required for dimming and color temperature adjustment. However, when the output (load) is short-circuited, the H-bridge malfunctions, and in severe cases, damages the bridge, rendering the circuit inoperable. Existing short-circuit detection circuits utilize numerous components, typically using a comparator to compare the output voltage. This results in a complex circuit structure and high cost. Therefore, a simple short-circuit detection circuit and an H-bridge two-wire output LED dimming driver are urgently needed to address these issues. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems in the prior art. To this end, the present invention provides a simple short-circuit detection circuit and an H-bridge two-wire output LED dimming power supply.

[0004] An embodiment of the present invention solves the technical problem by adopting a technical solution: a simple short-circuit detection circuit, including a rectifier bridge BD1, an optical coupler DU1, transistors Q5-Q8, a capacitor C1-2 and a resistor R1-3;

[0005] A first input end of the rectifier bridge BD1 is connected to one end of the lamp, a second input end is connected to the other end of the lamp, a first output end is respectively connected to one end of the capacitor C1, the emitter of the transistor Q5, and one end of the resistor R1, a second output end is respectively connected to the other end of the capacitor C1, one end of the resistor R3, and one end of the optocoupler DU1 light emitter, the other end of the resistor R1 is respectively connected to the base of the transistor Q5 and the emitter of the transistor Q6, the collector of the transistor Q5 is respectively connected to the base of the transistor Q6 and the other end of the resistor R3, and the collector of the transistor Q6 is connected to the other end of the optocoupler DU1 light emitter;

[0006] One end of the optocoupler DU1 light receiver is respectively connected to one end of the capacitor C2, one end of the resistor R2, the base of the transistor Q7 and the base of the transistor Q8, the other end of the resistor R2 is connected to the VCC end, the collector of the transistor Q7 is connected to the first dimming signal output end, the collector of the transistor Q8 is connected to the second dimming signal output end, and the other end of the optocoupler DU1 light receiver, the other end of the capacitor C2, the emitter of the transistor Q7 and the emitter of the transistor Q8 are grounded.

[0007] As one of the preferred embodiments of the present utility model, the rectifier bridge BD1 includes diodes D1-D4, the anode of the diode D1 and the cathode of the diode D3 serve as the first input terminal, the anode of the diode D2 and the cathode of the diode D4 serve as the second input terminal, the cathode of the diode D1 and the cathode of the diode D2 serve as the first output terminal, and the anode of the diode D3 and the cathode of the diode D4 serve as the second output terminal.

[0008] An H-bridge two-wire output LED dimming power supply, comprising an EMI filter circuit, an AC-DC circuit, an H-bridge two-wire output dimming circuit and the short-circuit detection circuit;

[0009] The input end of the EM I filter circuit is connected to an external power supply;

[0010] The input end of the AC-DC circuit is connected to the output end of the EM I filter circuit;

[0011] The H-bridge two-wire output dimming circuit is connected between the output end of the AC-DC circuit and the lamp;

[0012] The short-circuit protection circuit is connected between the H-bridge two-wire output dimming circuit and the lamp;

[0013] The H-bridge two-wire output dimming circuit can cut off the dimming signal output to the lamp when the short-circuit protection circuit detects a short circuit in the lamp.

[0014] The beneficial effects of the present invention include: a simple short-circuit detection circuit and an H-bridge two-wire output LED dimming power supply. The simple short-circuit detection circuit includes a rectifier bridge BD1, an optocoupler DU1, transistors Q5-Q8, capacitors C1-2, and resistors R1-3. The above circuit can quickly protect the H-bridge to avoid abnormal output operation due to long-term short circuit, and also avoid damage to the H-bridge circuit. At the same time, it can also report to the MCU circuit system for further processing, with the advantages of a small number of components, low cost, fast response, and stable performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0016] Figure 1 This is a block diagram of an H-bridge two-wire output LED dimming power supply.

[0017] Figure 2 This is a circuit diagram of an H-bridge two-wire output LED dimming power supply;

[0018] Figure 3 The following is a schematic diagram of a simple short-circuit detection circuit. DETAILED DESCRIPTION

[0019] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0020] In the description of this utility model, "above," "below," and "within" are understood to be exclusive of the number indicated, while "above," "below," and "within" are understood to be inclusive of the number indicated. The use of "first" and "second" is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, or implicitly specifying the number or order of the technical features indicated.

[0021] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0022] In this utility model, unless otherwise expressly defined, terms such as "disposed," "installed," and "connected" should be interpreted broadly. For example, they may refer to direct connection or indirect connection through an intermediate medium; fixed connection or detachable connection or integral molding; mechanical connection; internal communication between two components or interaction between two components. Those skilled in the art can reasonably determine the specific meanings of these terms in this utility model based on the specific content of the technical solution.

[0023] Reference Figures 1 to 3 , an H-bridge two-wire output LED dimming power supply, including an EMI filter circuit 10, an AC-DC circuit 20, an H-bridge two-wire output dimming circuit 30 and a short-circuit detection circuit 40;

[0024] The input end of the EM I filter circuit 10 is connected to an external power supply;

[0025] The input end of the AC-DC circuit 20 is connected to the output end of the EM I filter circuit 10;

[0026] The H-bridge two-wire output dimming circuit 30 is connected between the output end of the AC-DC circuit 20 and the lamp;

[0027] The short-circuit protection circuit 40 is connected between the H-bridge two-wire output dimming circuit 30 and the lamp;

[0028] The H-bridge two-wire output dimming circuit 30 can cut off the dimming signal output to the lamp when the short-circuit protection circuit 40 detects a short circuit in the lamp.

[0029] The working principle of this utility model is as follows:

[0030] ① When the system is powered on, AC power passes through the EMI filter circuit 10 and is then rectified into DC power by a rectifier bridge. When the AC-DC circuit 20 topology loop is operating stably, due to the voltage outer loop feedback and the fixed turns ratio of the transformer, the output stable voltages are V+, VCC, and VDD respectively. V+ and VCC are then supplied to the H-bridge circuit, and VCC is supplied to the MUC circuit. The MUC circuit outputs CW_PWM (the first dimming signal output terminal) to the driver chip U1 and WW_PWM (the second dimming signal output terminal) to the driver chip U2. The driver chip U1 outputs CW_H to the gate of the MOS transistor Q1, and the driver chip U1 outputs CW_L to the gate of the MOS transistor Q3. The driver chip U2 outputs WW_H to the gate of the MOS transistor Q2, and the driver chip U2 outputs WW_L to the gate of the MOS transistor Q4. CW_PWM and WW_PWM are complementary duty cycles output by the MCU circuit.

[0031] Specifically, when the cold light and warm light are brightest, CW_PWM and WW_PWM are complementary duty cycles, and VCC powers the driver chip U1 and driver chip U2. When CW_PWM is high and WW_PWM is low, CW_H is high, CW_L is low, WW_H is low, and WW_L is high. Therefore, V+ passes through MOS tube Q1, enters from the CW end of the lamp, and then exits from the WW end of the lamp through MOS tube Q4 and current limiting resistor R9 and returns to GND. At this time, the cold light of the lamp is bright; when CW_PWM is low and WW_PWM is high, CW_H is low, CW_L is high, WW_H is high, and WW_L is low. Therefore, V+ passes through MOS tube Q2, enters from the WW end of the lamp, and then exits from the CW end of the lamp through MOS tube Q3 and current limiting resistor R9 and returns to GND. At this time, the warm light of the lamp is bright; because of the control of frequency, the cold and warm light are brightest at this time;

[0032] When the cold light is brightest, CW_PWM is high and WW_PWM is low. At this time, CW_H is high, CW_L is low, WW_H is low, and WW_L is high. Therefore, V+ passes through MOS tube Q1, enters from the CW end of the lamp, and then comes out from the WW end of the lamp through MOS tube Q4 and current limiting resistor R9 and returns to GND. At this time, the cold light of the lamp is the brightest;

[0033] When the warm light is brightest, CW_PWM is low and WW_PWM is high. At this time, CW_H is low, CW_L is high, WW_H is high, and WW_L is low. Therefore, V+ passes through MOS tube Q2, enters from the WW end of the lamp, and then comes out from the CW end of the lamp through MOS tube Q3 and current limiting resistor R9 and returns to GND. At this time, the warm light of the lamp is the brightest;

[0034] ② In the short-circuit protection circuit 40, the short-circuit protection circuit 40 includes a rectifier bridge BD1, an optocoupler DU1, transistors Q5-Q8, a capacitor C1-2 and a resistor R1-3;

[0035] A first input end of the rectifier bridge BD1 is connected to one end of the lamp, a second input end is connected to the other end of the lamp, a first output end is respectively connected to one end of the capacitor C1, the emitter of the transistor Q5, and one end of the resistor R1, a second output end is respectively connected to the other end of the capacitor C1, one end of the resistor R3, and one end of the optocoupler DU1 light emitter, the other end of the resistor R1 is respectively connected to the base of the transistor Q5 and the emitter of the transistor Q6, the collector of the transistor Q5 is respectively connected to the base of the transistor Q6 and the other end of the resistor R3, and the collector of the transistor Q6 is connected to the other end of the optocoupler DU1 light emitter;

[0036] One end of the optocoupler DU1 light receiver is respectively connected to one end of the capacitor C2, one end of the resistor R2, the base of the transistor Q7 and the base of the transistor Q8, the other end of the resistor R2 is connected to the VCC end, the collector of the transistor Q7 is connected to the first dimming signal output end, the collector of the transistor Q8 is connected to the second dimming signal output end, and the other end of the optocoupler DU1 light receiver, the other end of the capacitor C2, the emitter of the transistor Q7 and the emitter of the transistor Q8 are grounded.

[0037] Specifically, the rectifier bridge BD1 includes diodes D1-D4, the anode of the diode D1 and the cathode of the diode D3 serve as the first input terminal, the anode of the diode D2 and the cathode of the diode D4 serve as the second input terminal, the cathode of the diode D1 and the cathode of the diode D2 serve as the first output terminal, and the anode of the diode D3 and the cathode of the diode D4 serve as the second output terminal; when the H-bridge output (load) is not short-circuited, when the H-bridge circuit flows from the CW terminal to the WW terminal, since CW and WW are respectively connected to the first input terminal and the second input terminal of the rectifier bridge BD1, after rectification After filtering by capacitor C1, the output DC voltage passes through the emitter of transistor Q5 and resistor R1, and then passes through the base of transistor Q5 and the emitter of transistor Q6. At this time, the base voltage of transistor Q5 is equal to the emitter voltage of transistor Q5, and transistor Q5 is not conducting. The collector of transistor Q5 is connected to the base of transistor Q6, so the base of transistor Q6 is at a low level, and the emitter voltage of transistor Q6 is equal to the base voltage of transistor Q5, and is at a high level. Transistor Q6 is turned on and passes through the light emitter of optocoupler DU1. At this time, the light receiver of optocoupler DU 1 is turned on, and the AD signal is pulled low. At this time, transistor Q7 and transistor Q8 are not conducting. The MUC circuit receives the signal AD as a low level and does not process it. CW_PWM and WW_PWM output normally, the H-bridge works normally, and the lamp lights up normally.

[0038] When the H-bridge output (load) is short-circuited, the H-bridge circuit Vcw=Vww. Since CW and WW are connected to the first input terminal and the second input terminal of the rectifier bridge BD1 respectively, the rectifier bridge BD1 has no output at this time, that is, the capacitor C1 is at a low level, and the transistors Q5, Q6 and the light emitter of the optocoupler DU1 are not conducting. At this time, the light receiver of the optocoupler DU1 is not conducting, and VCC enters the signal AD through the resistor R2. The signal AD is high level. The signal AD enters the base of the transistor Q7 and the base of the transistor Q8 and the MUC circuit respectively. At this time, the transistor Q7 and the transistor Q8 are turned on, and at the same time, CW_PWM and WW_PWM are pulled down, so that the H-bridge stops working and the lamp does not light up; the MUC circuit receives the signal AD as a high level, stops outputting CW_PWM and WW_PWM, and reports to the system for processing.

[0039] ③The advantages of the present invention are: using the short-circuit detection circuit when the H-bridge two-wire output LED dimming and color temperature adjustment power supply can quickly protect the H-bridge, avoid long-term short-circuit output malfunction, and also avoid damage to the H-bridge circuit. At the same time, it can also report to the MCU circuit system for further processing. This circuit is simplified and can be implemented with only 1 rectifier bridge, 1 optocoupler, and 4 transistors. It has the advantages of simple circuit connection, small number of components, low cost, fast response, and stable performance.

[0040] Of course, the present invention is not limited to the above-mentioned embodiments. Those skilled in the art may make equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications and substitutions are all included in the scope defined by the claims of this application.

Claims

1. A simple short-circuit detection circuit, characterized in that: Including rectifier bridge BD1, optocoupler DU1, transistors Q5-Q8, capacitors C1-2 and resistors R1-3; A first input end of the rectifier bridge BD1 is connected to one end of the lamp, a second input end is connected to the other end of the lamp, a first output end is respectively connected to one end of the capacitor C1, the emitter of the transistor Q5, and one end of the resistor R1, a second output end is respectively connected to the other end of the capacitor C1, one end of the resistor R3, and one end of the optocoupler DU1 light emitter, the other end of the resistor R1 is respectively connected to the base of the transistor Q5 and the emitter of the transistor Q6, the collector of the transistor Q5 is respectively connected to the base of the transistor Q6 and the other end of the resistor R3, and the collector of the transistor Q6 is connected to the other end of the optocoupler DU1 light emitter; One end of the optocoupler DU1 light receiver is respectively connected to one end of the capacitor C2, one end of the resistor R2, the base of the transistor Q7 and the base of the transistor Q8, the other end of the resistor R2 is connected to the VCC end, the collector of the transistor Q7 is connected to the first dimming signal output end, the collector of the transistor Q8 is connected to the second dimming signal output end, and the other end of the optocoupler DU1 light receiver, the other end of the capacitor C2, the emitter of the transistor Q7 and the emitter of the transistor Q8 are grounded.

2. A simple short-circuit detection circuit according to claim 1, characterized in that: The rectifier bridge BD1 includes diodes D1-D4, the anode of the diode D1 and the cathode of the diode D3 serve as a first input terminal, the anode of the diode D2 and the cathode of the diode D4 serve as a second input terminal, the cathode of the diode D1 and the cathode of the diode D2 serve as a first output terminal, and the anode of the diode D3 and the cathode of the diode D4 serve as a second output terminal.

3. An H-bridge two-wire output LED dimming power supply, characterized by: It comprises an EMI filter circuit (10), an AC-DC circuit (20), an H-bridge two-line output dimming circuit (30), and a short-circuit detection circuit (40) according to any one of claims 1 to 2; The input end of the EMI filter circuit (10) is connected to an external power supply; The input end of the AC-DC circuit (20) is connected to the output end of the EMI filter circuit (10); The H-bridge two-line output dimming circuit (30) is connected between the output end of the AC-DC circuit (20) and the lamp; The short-circuit protection circuit (40) is connected between the H-bridge two-line output dimming circuit (30) and the lamp; The H-bridge two-line output dimming circuit (30) can cut off the dimming signal output to the lamp when the short-circuit protection circuit (40) detects that the lamp is short-circuited.

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