CN209845367U

CN209845367U - Multi-path PWM dimming self-adaptive switching circuit for LED driving

Info

Publication number: CN209845367U
Application number: CN201822060486.4U
Authority: CN
Inventors: 陈实; 胡荣辉; 杨传行
Original assignee: Huizhou CDN Industrial Development Co Ltd
Current assignee: Huizhou CDN Industrial Development Co Ltd
Priority date: 2018-12-10
Filing date: 2018-12-10
Publication date: 2019-12-24
Anticipated expiration: 2028-12-10

Abstract

The utility model discloses a multipath PWM dimming self-adaptive switching circuit for LED driving, which comprises a parallel input impedance array and a signal output circuit which are connected in sequence; the parallel input impedance array comprises at least two parallel variable impedance units, the input end of each variable impedance unit is connected with a PWM signal source, the output end of each variable impedance unit is connected with the signal output circuit, each variable impedance unit comprises a diode and a resistor which are connected in parallel, and the cathode and the anode of each diode are respectively connected with the PWM signal source and the signal output circuit. The utility model discloses an effective benefit lies in: when one LED is driven and matched with a plurality of dimming systems to be used together, the circuit for PWM dimming self-adaptive switching of the minimum duty ratio can be realized through a plurality of simple resistors, diodes and triodes, the circuit structure is simple, the product application is easy, and social resources are saved.

Description

Multi-path PWM dimming self-adaptive switching circuit for LED driving

Technical Field

The utility model relates to a LED dimming control field, in particular to be used for LED driven multichannel PWM to adjust luminance self-adaptation switch circuit.

Background

In the use of current lighting systems, LEDs play an extremely important role. The LED dimming control system is more and more, and includes a thyristor dimming system, a 0-10V dimming system, a DALI dimming system, etc., when one LED driver is matched with a plurality of dimming systems for use together, the LED driver often needs to use an upper control signal for switching, at present, most of the LED drivers use a logic control unit or a single chip microcomputer for programming to perform judgment and switching of various logic circuits, so that the LED dimming control system is complex in control, high in cost, and inconvenient in terminal application.

Disclosure of Invention

The utility model discloses an overcome above-mentioned prior art at least one kind defect (not enough), provide one kind and be used for LED driven multichannel PWM to adjust luminance self-adaptation switching circuit.

In order to solve the technical problem, the technical scheme of the utility model as follows:

a multi-path PWM dimming self-adaptive switching circuit for LED driving comprises a parallel input impedance array and a signal output circuit which are sequentially connected; the parallel input impedance array comprises at least two parallel variable impedance units, the input end of each variable impedance unit is connected with a PWM signal source, the output end of each variable impedance unit is connected with the signal output circuit, each variable impedance unit comprises a diode and a resistor which are connected in parallel, and the cathode and the anode of each diode are respectively connected with the PWM signal source and the signal output circuit.

The input end of the voltage amplifying circuit is connected with the signal output end of the parallel input impedance array, and the output end of the voltage amplifying circuit is connected with the signal input end of the power amplifying circuit; the output end of the power amplifying circuit is connected with the input end of the signal output circuit.

Furthermore, the voltage amplifying circuit comprises a first MOS tube and a first voltage stabilizing diode, the grid electrode of the first MOS tube is connected with the output end of the parallel input impedance array, the drain electrode of the first MOS tube is connected with the signal input end of the power amplifying circuit, and the source electrode of the first MOS tube is grounded; and the grid electrode of the first MOS tube is also reversely connected with the first voltage-stabilizing tube and then grounded.

Further, the power amplifying circuit comprises a first resistor, a second resistor and a triode; one end of the first resistor is connected with one end of the second resistor in parallel and then is connected with the drain electrode of the second MOS tube, the other end of the first resistor is connected with the base electrode of the triode, and the other end of the second resistor is connected with the emitting electrode of the triode; the collector of the triode is used as output and is connected with the drive circuit.

Furthermore, the power amplification circuit also comprises a second voltage stabilizing diode and a second MOS tube, wherein the cathode of the second voltage stabilizing diode is connected with the drain electrode of the first MOS tube, and the anode of the second voltage stabilizing diode is connected with the grid electrode of the second MOS tube; and the drain electrode of the second MOS tube is connected with the driving circuit.

Further, the signal output circuit comprises a third resistor and a fourth resistor; one end of the third resistor is connected with an external power supply, and the other end of the third resistor is connected with the emitting electrode of the triode; one end of the fourth resistor is connected with the collector of the triode, and the other end of the fourth resistor is connected with the driving circuit as a signal output.

Further, the number of the variable impedance units is 4.

The utility model discloses an effective benefit lies in: when one LED is driven and matched with a plurality of dimming systems to be used together, the circuit for PWM dimming self-adaptive switching of the minimum duty ratio can be realized through a plurality of simple resistors, diodes and triodes, the circuit structure is simple, the product application is easy, and social resources are saved.

Drawings

Fig. 1 is a system block diagram of embodiment 1 of the present invention.

Fig. 2 is a schematic circuit diagram of an input impedance array according to embodiment 1 of the present invention.

Fig. 3 is a system block diagram of embodiment 2 of the present invention.

Fig. 4 is a schematic circuit diagram of embodiment 2 of the present invention.

The drawings are for illustrative purposes only and are not to be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted; the same or similar reference numerals correspond to the same or similar parts; the terms describing positional relationships in the drawings are for illustrative purposes only and are not to be construed as limiting the patent.

Detailed Description

The technical scheme of the invention is further explained by combining the drawings and the embodiment.

Example 1

The embodiment discloses a multi-path PWM dimming self-adaptive switching circuit for LED driving, which comprises a parallel input impedance array 1 and a signal output circuit 2 which are connected in sequence as shown in FIGS. 1-2; the parallel input impedance array 1 comprises at least two parallel variable impedance units, wherein the input end of each variable impedance unit is connected with a PWM signal source, the output end of each variable impedance unit is connected with the signal output circuit 2, each variable impedance unit comprises a diode D6 and a resistor R21 which are connected in parallel, and the cathode and the anode of the diode D6 are respectively connected with the PWM signal source and the signal output circuit 2.

Specifically, the cathodes of the diodes D6 are respectively connected to the corresponding PWM signal sources, and the anodes thereof are respectively connected in parallel and then connected to the input terminal of the signal output circuit; in the same time period, when the PWM signal source of each path is at a high level, the cathode of the diode D6 is connected to the PWM signal source, and the diode D6 remains closed, so that the current does not pass through the diode D6, the input impedance value at this time is the resistance value of the resistor R21, and the signal output is still at a high level, when the PWM signal source of any path is at a low level, the input impedance value at this time is the tube voltage drop of the diode D6, the diode D6 is turned on, the PWM input signals respectively flow through the diode D6 and the resistor R21, but since the impedance value generated when the diode D6 is turned on is small, most of the current flows out of the diode D6, the signal output is at a low level at this time, the signal switching of the previous-stage dimming system is realized, and the output duty ratio is the minimum duty ratio.

Example 2

In this embodiment, another adaptive switching circuit is disclosed, as shown in fig. 3 to 4, the difference between this embodiment and embodiment 1 is that, in order to improve the stability of the switching circuit and adapt to the driving of the LED with larger driving, this embodiment further includes a voltage amplifying circuit 3 and a power amplifying circuit 4 which are arranged between the parallel input impedance array 1 and the signal output circuit 2, wherein the input end of the voltage amplifying circuit 3 and the parallel input impedance array 1 are connected in parallel

The output end of the power amplifier circuit 4 is connected with the input end of the signal output circuit 2.

In this embodiment, the parallel input impedance array 1 includes 4 variable impedance units connected in parallel, which are respectively RP1, RP2, RP3 and RP4, specifically, the RP1 includes a first diode D6A and a fifth resistor R6A connected in parallel, the RP2 includes a second diode D6B and a sixth resistor R21B connected in parallel, the RP3 includes a third diode D6C and a seventh resistor R21C connected in parallel, the RP4 includes a fourth diode D6D and an eighth resistor R21D connected in parallel, wherein cathodes of the first diode D6A, the second diode D6B, the third diode D6C and the fourth diode D6D are respectively connected to corresponding PWM signal sources, and anodes thereof are respectively connected in parallel to an input terminal of the voltage amplifying circuit 3.

The PWM signal sources mentioned in this embodiment respectively correspond to PWM signals output by a plurality of previous dimming control systems, that is, the PWM signal sources include, but are not limited to, the 4 PWM signals described above, and the dimming control system capable of adjusting the driving of the LED can be used as a PWM signal source for providing this embodiment, which is not limited herein.

Further, the voltage amplifying circuit 3 includes a first MOS transistor Q1, wherein a gate of the first MOS transistor Q1 is connected to the output terminal of the input impedance array 1 as a driving voltage of the first MOS transistor Q1, a source of the first MOS transistor Q1 is grounded, and a drain of the first MOS transistor Q1 is connected to the input terminal of the power amplifying circuit 4 as a current output.

In order to stabilize the input voltage and protect the circuit, the voltage amplifying circuit 3 further includes a first zener diode ZD4, wherein an anode of the first zener diode ZD4 is connected to the source of the first MOS transistor Q1, and a cathode of the first zener diode ZD4 is connected to the output terminal of the input impedance array 1.

The voltage amplifying circuit 3 amplifies the input voltage, specifically, when the input PWM signal source is at a low level, the impedance value is the tube voltage drop of the diode D6, and the node voltage of the first MOS tube Q1 is reduced through the diode D6, so that the first MOS tube Q1 is turned off when the PWM signal source is at a low level.

In this embodiment, the power amplifying circuit 4 includes a first resistor R1, a second resistor R2, a second MOS transistor Q2, a second zener diode ZD5, and a triode Q11, specifically, a base of the triode Q11 is connected to one end of the first resistor R1, an emitter is connected to one end of the second resistor R2, and a collector is connected to the input end of the signal output circuit 2, wherein the first resistor R1 and the second resistor R2 are connected in parallel, then connected to a cathode of the second zener diode ZD5, and finally connected to the output end of the voltage amplifying circuit 3, and an anode of the second zener diode ZD5 is connected to a gate of the second MOS transistor Q2.

In this embodiment, the first resistor R1 and the second resistor R2 function to adjust the amplification factor of the transistor Q11.

The signal output circuit 2 in this embodiment includes a third resistor R3, a fourth resistor R4 and an external power supply, wherein two ends of the third resistor R3 are respectively connected to the emitter of the transistor Q11 and the external power supply; one end of the fourth resistor R4 is connected to the collector of the transistor Q11, and the other end is connected to the driving LED.

Specifically, the third resistor R3 and the fourth resistor R4 are impedance matching of PWM output, limit the maximum current of PWM, and avoid obvious influence on the operating state of the device itself after the drive is connected.

The specific working principle is as follows: the input current is power amplified by transistor Q11 for driving the drive current of the larger LED. In the same time period, when the PWM signal is at a high level, the impedance is the resistance of the resistor R21 in the input impedance array 1, and the node voltage of the gate of the first MOS transistor Q1 is at a high level, at this time, the first MOS transistor Q1 is turned on, and current flows in from the source and flows out from the drain, and the power is amplified and then output to drive the LED which can drive a large current. In addition, after the voltage is reversed by the second zener diode ZD5, the second MOS transistor Q2 is turned off, and the output is a high level, where one of the two paths is a low level, the input impedance is a voltage drop of the diode D6, and the voltage of the node of the first MOS transistor Q1 is reduced by the diode D6, so that the voltage of the gate in the first MOS transistor Q1 is smaller than the driving voltage, although the other three PWMs are high levels, the voltage of the node of the gate in the first MOS transistor Q1 is pulled low and smaller than the driving voltage, the first MOS transistor Q1 is turned off, the following PWM signal does not drive the output, and the output is grounded, the output PWM signal is a low level, the switching circuit is controlled by the duty ratio of the smallest path, and the finally output PWM signal is the duty ratio of the smallest path of the input PWM signal, thereby implementing adaptive switching of the multi-path dimming system.

It is obvious that the above embodiments of the present invention are only examples for clearly illustrating the present invention, and are not limitations to the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A multi-path PWM dimming self-adaptive switching circuit for LED driving is characterized by comprising an input impedance array (1) and a signal output circuit (2) which are connected in parallel in sequence; the parallel input impedance array (1) comprises at least two parallel variable impedance units, the input end of each variable impedance unit is connected with a PWM signal source, the output end of each variable impedance unit is connected with the signal output circuit (2), each variable impedance unit comprises a diode (D6) and a resistor (R21) which are connected in parallel, and the cathode and the anode of each diode (D6) are respectively connected with the PWM signal source and the signal output circuit (2).

2. The multi-channel PWM dimming adaptive switching circuit for the LED driving according to claim 1, further comprising a voltage amplifying circuit (3) and a power amplifying circuit (4) which are arranged between the parallel input impedance array (1) and the signal output circuit (2), wherein the input end of the voltage amplifying circuit (3) is connected with the signal output end of the parallel input impedance array, and the output end of the voltage amplifying circuit is connected with the signal input end of the power amplifying circuit (4); the output end of the power amplifying circuit (4) is connected with the input end of the signal output circuit (2).

3. The multi-channel PWM dimming adaptive switching circuit for the LED driving according to claim 2, wherein the voltage amplifying circuit (3) comprises a first MOS transistor (Q1) and a first voltage-stabilizing diode (ZD 4), the gate of the first MOS transistor (Q1) is connected with the output end of the parallel input impedance array (1), the drain is connected with the signal input end of the power amplifying circuit (4), and the source is grounded; the grid of the first MOS transistor (Q1) is also reversely connected with the first voltage-stabilizing diode (ZD 4) and then grounded.

4. The multi-PWM dimming adaptive switching circuit for LED driving according to claim 2, wherein the power amplifying circuit (4) comprises a first resistor (R1), a second resistor (R2), a triode (Q11) and a second MOS transistor (Q2); one end of a first resistor (R1) is connected with one end of a second resistor (R2) in parallel and then connected with the drain electrode of the second MOS transistor (Q2), the other end of the first resistor (R1) is connected with the base electrode of the triode (Q11), and the other end of the second resistor (R2) is connected with the emitter electrode of the triode (Q11); the collector of the transistor (Q11) is connected as an output to the driver circuit.

5. The multi-channel PWM dimming adaptive switching circuit for LED driving according to claim 4, wherein the power amplifying circuit (4) further comprises a second zener diode (ZD 5); the cathode of the second zener diode (ZD 5) is connected with the drain of the first MOS transistor (Q1), and the anode of the second zener diode is connected with the gate of the second MOS transistor (Q2); the drain electrode of the second MOS tube (Q2) is connected with a driving circuit.

6. The multi-PWM dimming adaptive switching circuit for LED driving according to claim 4, wherein the signal output circuit (2) comprises a third resistor (R3) and a fourth resistor (R4); one end of the third resistor (R3) is connected with an external power supply, and the other end of the third resistor (R3) is connected with the emitter of the triode (Q11); one end of the fourth resistor (R4) is connected with the collector of the triode (Q11), and the other end of the fourth resistor is connected with a driving circuit as a signal output.

7. The multi-PWM dimming adaptive switching circuit for LED driving according to claim 1, wherein the number of the variable impedance units is 4.