阅读说明：本技术 一种led负载均流保护电路 (LED load current-sharing protection circuit ) 是由 侯宇 周芳 蓝贤福 何贵平 罗彪 于 2020-12-24 设计创作，主要内容包括：本发明公开了一种LED负载均流保护电路,包括：电源模块；断路检测模块,与LED负载支路连接,用于检测LED负载支路的开路故障信息或者正常工作信息；开关模块,与电源模块、断路检测模块连接,用于根据开路故障断开或根据正常工作信息闭合；恒流驱动模块,与开关模块、LED负载支路连接,用于在开关模块断开时,恒流驱动模块断开与电源模块连接；在开关模块闭合时,恒流驱动模块通过开关模块与电源模块连接,并驱动LED负载支路；均流模块,与恒流驱动模块连接,用于在开关模块闭合时,受所述恒流驱动模块的驱动为所述LED负载支路实现均流控制；本发明能够在实现多路LED负载高精度均流的同时保护LED负载。(The invention discloses a current-sharing protection circuit for LED loads, which comprises: a power supply module; the open circuit detection module is connected with the LED load branch and used for detecting open circuit fault information or normal working information of the LED load branch; the switch module is connected with the power supply module and the open circuit detection module and is used for being disconnected according to open circuit faults or being closed according to normal working information; the constant current driving module is connected with the switch module and the LED load branch circuit and is used for disconnecting the switch module and the power supply module when the switch module is disconnected; when the switch module is closed, the constant current driving module is connected with the power supply module through the switch module and drives the LED load branch; the current sharing module is connected with the constant current driving module and is used for realizing current sharing control on the LED load branch circuit under the driving of the constant current driving module when the switch module is closed; the invention can realize high-precision current sharing of multiple paths of LED loads and protect the LED loads at the same time.)

1. An LED load current-sharing protection circuit is used for protecting an LED load, wherein the LED load comprises one or more LED load branches with different models, and the circuit comprises:

a power supply module;

the open circuit detection module is connected with the LED load branch and used for detecting open circuit fault information or normal working information of the LED load branch;

the switch module is connected with the power supply module and the open circuit detection module and is used for being switched off according to the open circuit fault or being switched on according to normal working information;

the constant current driving module is connected with the switch module and the LED load branch circuit, and when the switch module is disconnected, the constant current driving module is disconnected from the power supply module; when the switch module is closed, the constant current driving module is connected with the power supply module through the switch module and outputs a constant current to drive the LED load branch circuit;

and the current sharing module is connected with the constant current driving module and is used for realizing current sharing control for the LED load branch circuit under the driving of the constant current driving module when the switch module is closed.

2. The LED load share protection circuit of claim 1, wherein the power module comprises: a filtering anti-reflection module;

the input end of the filtering anti-reversion module is connected with the power supply module, and the output end of the filtering anti-reversion module is connected with the switch module.

3. The LED load current sharing protection circuit according to claim 1, wherein the current sharing module comprises a current sharing resistor, a plurality of current sharing triodes with the same number as the LED load branches; one end of the current-sharing resistor is connected with the base electrode of the current-sharing triode, and the LED load branch is grounded through the CE junction of the current-sharing triode; the other end of the current-sharing resistor is connected with the constant current driving module and used for enabling the current-sharing triode to work in an amplification region when being conducted, and the base currents are equal.

4. The LED load current sharing protection circuit according to claim 1, wherein the open circuit detection module comprises a detection triode, a detection diode, a second MOS transistor, a third MOS transistor, a pull-up resistor, a first voltage-dividing resistor, and a second voltage-dividing resistor;

the number of the detection triodes and the detection diodes is the same as that of the LED load branches; the base electrode of the detection triode is connected with the LED load branch circuit, the emitting electrode of the detection triode is grounded, the collector electrode of the detection triode is connected with the positive end of the detection diode, the negative end of the detection diode is connected with the grid electrode of a third MOS (metal oxide semiconductor) tube, the source electrode of the third MOS tube is grounded, the drain electrode of the third MOS tube is connected with the grid electrode of the second MOS tube, the source electrode of the second MOS tube is grounded, and the drain electrode of the second MOS tube is connected with the switch module; the positive end of the detection diode is connected with the power supply module through the pull-up resistor; the grid electrode of the second MOS tube is grounded through the first voltage-dividing resistor, and the grid electrode of the second MOS tube is connected with the power supply module through the second voltage-dividing resistor.

5. The LED load share protection circuit of claim 1, wherein the open circuit detection module further comprises a base diode; each LED load branch is provided with the base diode; and the base electrode of the detection triode is grounded through the base electrode diode.

6. The LED load current sharing protection circuit according to claim 4, wherein the switch module comprises a first MOS transistor; the grid electrode of the first MOS tube is connected with the drain electrode of the second MOS tube, the source electrode of the first MOS tube is connected with the power supply module, and the drain electrode of the first MOS tube is connected with the constant current driving module.

7. The LED load current sharing protection circuit of claim 2, wherein the filtering anti-reverse module comprises a first capacitor, a second capacitor, a bleeder resistor, a TVS tube, an anti-reverse diode, and a third capacitor;

the power supply module is grounded through the first capacitor and the second capacitor; the power supply module is grounded through the bleeder resistor; the power supply module is grounded through the TVS tube; the power supply module is grounded through the anti-reverse diode and the third capacitor; and the negative end of the anti-reverse diode is the output of the filtering anti-reverse module.

8. The LED load current sharing protection circuit of claim 3, wherein the current sharing transistor is an NPN transistor.

Technical Field

The invention belongs to the technical field of LED loads, and particularly relates to an LED load current-sharing protection circuit.

Background

The switching power supply is commonly used in a circuit, and is widely applied to various driving circuits due to its advantages of high efficiency and energy saving, wherein the switching circuit can be maximally utilized in order to save circuit cost. The LED load current-sharing protection circuit is applied to a switching circuit. In a switching circuit, when the number of parallel LED strings is large, the number of branches of an LED load is different, the types of LEDs connected in parallel with the branches of the LED load are different and the like, the current sharing of the branches becomes a big problem, so that the LED loads in the switching power supply can only be connected in series; in some fields, the LED load is required to be subjected to one path of LED load open circuit, all the LED loads are open circuit, and for a switching power supply, one-off and full-off of multiple paths of LED loads are also a problem; when one LED is broken, the protection of all LED loads cannot be cut off, and the light distribution requirements of customers cannot be met in some fields.

Disclosure of Invention

In order to overcome the technical defects, the invention provides an LED load current sharing protection circuit, which aims to solve the problems.

In order to solve the problems, the invention is realized according to the following technical scheme:

an LED load current-sharing protection circuit for protecting an LED load while achieving high-precision current sharing, the LED load comprising one or more different LED load branches, the circuit comprising:

a power supply module;

the open circuit detection module is connected with the LED load branch and used for detecting open circuit fault information or normal working information of the LED load branch;

the switch module is connected with the power supply module and the open circuit detection module and is used for being switched off according to the open circuit fault or being switched on according to normal working information;

the constant current driving module is connected with the switch module and the LED load branch circuit, and when the switch module is disconnected, the constant current driving module is disconnected from the power supply module; when the switch module is closed, the constant current driving module is connected with the power supply module through the switch module and drives the LED load branch circuit;

and the current sharing module is connected with the constant current driving module and is used for realizing current sharing control on the LED load branch circuit under the driving of the constant current driving module when the switch module is closed.

As a further improvement of the present invention, the power supply module includes: a filtering anti-reflection module;

the input end of the filtering anti-reversion module is connected with the power supply module, and the output end of the filtering anti-reversion module is connected with the switch module.

As a further improvement of the invention, the current-sharing module comprises a current-sharing resistor and a plurality of current-sharing triodes with the same number as the LED load branches; one end of the current-sharing resistor is connected with the base electrode of the current-sharing triode, and the LED load branch is grounded through the CE junction of the current-sharing triode; the other end of the current-sharing resistor is connected with the constant current driving module and used for enabling the current-sharing triode to work in an amplification region when being conducted, enabling the base current of the current-sharing triode to be consistent, and adjusting the resistance value of the resistor can achieve high-precision current sharing.

As a further improvement of the present invention, the disconnection detecting module includes a detecting transistor, a detecting diode, a second MOS transistor, a third MOS transistor, a pull-up resistor, a first voltage dividing resistor, and a second voltage dividing resistor;

the number of the detection triodes and the detection diodes is the same as that of the LED load branches; the base electrode of the detection triode is connected with the LED load branch circuit, the emitting electrode of the detection triode is grounded, the collector electrode of the detection triode is connected with the positive end of the detection diode, the negative end of the detection diode is connected with the grid electrode of a third MOS (metal oxide semiconductor) tube, the source electrode of the third MOS tube is grounded, the drain electrode of the third MOS tube is connected with the grid electrode of the second MOS tube, the source electrode of the second MOS tube is grounded, and the drain electrode of the second MOS tube is connected with the switch module; the positive end of the detection diode is connected with the power supply module through the pull-up resistor; the grid electrode of the second MOS tube is grounded through the first voltage-dividing resistor, and the grid electrode of the second MOS tube is connected with the power supply module through the second voltage-dividing resistor.

As a further improvement of the present invention, the open circuit detection module further comprises a base diode; each LED load branch is provided with the base diode; and the base electrode of the detection triode is grounded through the base electrode diode.

As a further improvement of the present invention, the switch module includes a first MOS transistor; the grid electrode of the first MOS tube is connected with the drain electrode of the second MOS tube, the source electrode of the first MOS tube is connected with the power supply module, and the drain electrode of the first MOS tube is connected with the constant current driving module;

as a further improvement of the invention, the filtering anti-reverse module comprises a first capacitor, a second capacitor, a leakage resistor, a TVS (transient voltage suppressor), an anti-reverse diode and a third capacitor;

the power supply module is grounded through the first capacitor and the second capacitor; the power supply module is grounded through the bleeder resistor; the power supply module is grounded through the TVS tube; the power supply module is grounded through the anti-reverse diode and the third capacitor; and the negative end of the anti-reverse diode is the output of the filtering anti-reverse module.

As a further improvement of the invention, the current-sharing triode is an NPN triode.

Compared with the prior art, the invention has the following beneficial effects: firstly, whether the LED load branches work normally is detected through a broken circuit detection module, when a certain LED load branch breaks down, fault information is fed back to a switch module, and the switch module directly cuts off the constant current output of a constant current driving module, so that the LED load is protected; secondly, a constant current driving module and a current equalizing module are arranged, and for the condition that a plurality of paths of LED load branches are contained and the quantity of LEDs contained in each path of LED load branch is different or the types of LEDs are different, the current equalizing of each path of LED load branch can be realized at high precision.

Drawings

Embodiments of the invention are described in further detail below with reference to the attached drawing figures, wherein:

fig. 1 is a block diagram of a current sharing protection circuit for an LED load according to an embodiment;

FIG. 2 is a schematic circuit diagram of the LED load current sharing protection circuit according to an embodiment;

FIG. 3 is a schematic circuit diagram of the filtering anti-reverse circuit according to the first embodiment;

FIG. 4 is a schematic circuit diagram of the switch module according to one embodiment;

FIG. 5 is a schematic circuit diagram of the disconnection detection module according to an embodiment;

fig. 6 is a schematic circuit diagram of the LED load branch and the current equalizing module according to the first embodiment.

Description of the labeling: 1. a power supply module; 2. a filtering anti-reflection module; 3. a switch module; 4. a constant current driving module; 5. an LED load branch; 6. a disconnection detection module; 7. and a current equalizing module.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

Example one

This embodiment provides a LED load protection circuit that flow equalizes for protect LED load when each branch road load flows equalize, LED load includes one or the different LED load branch road of multichannel, and multichannel LED load protection circuit includes:

a power supply module 1;

the open circuit detection module 6 is connected with the LED load branch 5 and used for detecting open circuit fault information or normal working information of the LED load branch 5;

the switch module 3 is connected with the power module 1 and the open circuit detection module 6 and is used for being disconnected according to open circuit faults or being closed according to normal working information;

the constant current driving module 4 is connected with the switch module 3 and the LED load branch 5, and when the switch module 3 is disconnected, the constant current driving module 4 is disconnected with the power supply module 1; when the switch module 3 is closed, the constant current driving module 4 is connected with the power supply module 1 through the switch module 3 and drives the LED load branch 5;

and the current-sharing module 7 is connected with the constant-current driving module 4 and is used for realizing current-sharing control on the LED load branch 5 under the driving of the constant-current driving module 4 when the switch module 3 is closed.

Specifically, the bases of the current-sharing triode are connected and then connected with the current-sharing resistor to balance the voltage difference of each branch, and then high-precision current-sharing control is provided for the LED load branch 5.

For example, in a multi-path LED load, when the number of parallel LED strings is large, the number of branches of the LED load is different, the LED models of the parallel LED branches of the LED load are different, and the like, the current sharing of each LED load branch 5 becomes a problem which needs to be solved urgently at present. In this embodiment, 3 LED load branches 5 are taken as an example, a first LED load branch 5 is formed by connecting 6 LEDs in series (LED1, LED2, … …, and LED6), a second LED load branch 5 is formed by connecting 5 LEDs in series (LED7, LED8, … …, and LED11), and a third LED load branch 5 is formed by connecting 4 LEDs in series (LED12, LED13, … …, and LED15), which further describes this embodiment.

Specifically, the current sharing module 7 includes current sharing resistors R14 and 3 current sharing triodes: a seventh triode Q7, an eighth triode Q8, a ninth triode Q9; the current sharing transistor may be, but is not limited to, an NPN transistor. The first LED load branch 5 is grounded through a CE junction of the ninth transistor Q9, the second LED load branch 5 is grounded through a CE junction of the eighth transistor Q8, and the third LED load branch 5 is grounded through a CE junction of the seventh transistor Q7. The constant current driving module 4 is connected with the bases of the seventh triode Q7, the eighth triode Q8 and the ninth triode Q9 through a current sharing resistor R14, and is used for enabling the current sharing triode to work in an amplification region when being conducted. The bases of the branch triodes are connected together, the current-sharing resistor R14 takes electricity from the LED input end, the current-sharing resistor R14 can be set to a resistance value according to the actual LED load condition and can be used for adjusting the current-sharing precision, so that the seventh triode Q7, the eighth triode Q8 and the ninth triode Q9 are always in an amplification area, and the current of the collector is also the same as the bases of the seventh triode Q7, the eighth triode Q8 and the ninth triode Q9, so that the differential pressure generated by each branch can be balanced, and the high-precision current sharing is realized.

In the above embodiment, the power supply module 1 includes: a filtering anti-reflection module 2; the input end of the filtering anti-reflection module 2 is connected with the power supply module 1, and the output end of the filtering anti-reflection module 2 is connected with the switch module 3. The filtering anti-reflection module 2 comprises a first capacitor C1, a second capacitor C2, a current leakage resistor R1, a TVS tube TVS1, an anti-reflection diode D1 and a third capacitor C3; the power module 1 is grounded through a first capacitor C1 and a second capacitor C2; the power supply module 1 is grounded through a bleeder resistor R1; the power module 1 is grounded through a TVS tube; the power supply module 1 is grounded through an anti-reverse diode D1 and a third capacitor C3; the negative end of the anti-reverse diode D1 is the output of the filtering anti-reverse module 2. And the anti-reflection filter circuit can provide stable power input for subsequent circuits.

In the above embodiment, the disconnection detecting module 6 includes detecting transistors (a fourth transistor Q4, a fifth transistor Q5, a sixth transistor Q6), detecting diodes (a second diode D2, a third diode D3, a fourth diode D4), a second MOS transistor Q2, a third MOS transistor Q3, pull-up resistors (an eighth resistor R8, a ninth resistor R9, a tenth resistor R10), a first voltage-dividing resistor R6, a second voltage-dividing resistor R5, base diodes (a fifth diode D5 and a sixth diode D6, a seventh diode D7 and an eighth diode D8, a ninth diode D9 and a twelfth diode D10);

the base electrode of the fourth triode Q4 is connected with the negative end of the LED6 in the first LED load branch 5, the emitter electrode is grounded, and the collector electrode is connected with the positive end of the second diode D2; the base electrode of the fifth triode Q5 is connected with the negative end of the LED11 in the second LED load branch 5, the emitter electrode is grounded, and the collector electrode is connected with the positive end of the third diode D3; the base of the sixth triode Q6 is connected with the negative terminal of the LED15 in the third LED load branch 5, the emitter is grounded, and the collector is connected with the positive terminal of the fourth diode D4; the negative end of the second diode D2, the negative end of the third diode D3 and the negative end of the fourth diode D4 are all connected with the gate of a third MOS transistor Q3, the source of the third MOS transistor Q3 is grounded, the drain of the third MOS transistor Q3 is connected with the gate of a second MOS transistor Q2, the source of the second MOS transistor Q2 is grounded, and the drain of the second MOS transistor Q2 is connected with the switch module 3; the gate Q2 of the second MOS transistor is grounded through a first voltage-dividing resistor R6, and the gate Q2 of the second MOS transistor is connected to the power module 1 through a second voltage-dividing resistor R5.

The base electrode of the detection triode is grounded through a group of base electrode diodes and the current-sharing triode, the sum of the voltage drops of the base electrode diodes and the current-sharing triode is the base electrode of the detection triode, and the sum of the voltage drops of the base electrode diodes and the current-sharing triode only needs to meet the conduction voltage drop of the detection triode.

In the above embodiment, the switch module 3 includes the first MOS transistor Q1; the gate of the first MOS transistor Q1 is connected to the drain of the second MOS transistor Q2, the source of the first MOS transistor Q1 is connected to the power module 1, and the drain of the first MOS transistor Q1 is connected to the constant current driving module 4.

Specifically, in the disconnection detection module 6, the base diode provides detection voltage for the detection triode, and when the LED load of each branch works normally, the voltage detected by the bases of the detection triodes Q4, Q5 and Q6 is the sum of the voltage drops of the base diode and the current-sharing triode of the LED load of each branch; the sum of the voltage drops meets the conduction voltage drop of the detection triode, at the moment, the detection triodes Q4, Q5 and Q6 are conducted, the voltage of the collector of the detection triode is pulled to the ground, a low level is output to the third MOS tube Q3 for the detection diodes D2, D3 and D4, Q3 can be but is not limited to N-MOS, as the MOS tubes are voltage control devices, no conduction voltage difference exists between the grid electrode and the source electrode of Q3, Q3 is in a cut-off region, a high level is fed back to the drain electrode of the second MOS tube Q2 of the N-MOS, a conduction voltage difference exists between the grid electrode and the source electrode of Q2, Q2 is in a conduction state, the drain electrode of Q2 is pulled to the ground, a low level is fed back to the grid electrode of the first MOS tube Q1 of the P-MOS in the switch module 3, a conduction voltage difference exists between the grid electrode and the source electrode of Q1, Q1 is conducted to further.

More specifically, for example, when one LED of the second LED load branch 5 is disconnected, the detection voltage of the base of the triode Q8 is in a floating state, the collector provides a high level to the diode D3 through the pull-up resistor R9, the gate of the Q3N-MOS is also at a high level, the Q3 is turned on, the drain of the Q3 is pulled to the ground, a low level is output to the Q2N-MOS, the Q2 is not turned on without voltage difference, the drain of the Q2 outputs a high level to the switching module 3Q 1P-MOS, the voltage difference between the gate and the source of the Q1 is much smaller than the conduction voltage difference of the MOS, the switching module 3Q1 is turned off, the constant current driving module 4 does not have a working voltage to stop working, and the whole LED load branch 5 is in a turn.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, so that any modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.