Dimming control circuit, LED driving circuit and dimming LED

Abstract

The utility model provides a dimming control circuit, an LED drive circuit and a dimming LED. The dimming control circuit comprises a power supply circuit, the output end of which is connected with a load; the power control tube is connected between the power supply circuit and a load; the input end of the control driving circuit is connected with the output end of the power supply circuit, and the output end is connected with the grid electrode of the power control tube; the short-circuit protection circuit comprises a voltage stabilizing diode connected with the output end of the power supply circuit and a triode connected with the grid electrode of the power control tube, the voltage stabilizing diode is connected with the triode, and when the power supply circuit and / or the load are / is short-circuited, the voltage stabilizing diode controls the triode to be switched on, so that the power control tube is switched off, and the short-circuit protection circuit is switched off. Damage caused by current flowing through the power control tube in an abnormal short circuit state is avoided. Compared with the prior art, the short-circuit protection circuit adopted by the dimming control circuit not only is fast in response speed and low in cost, but also can be applied to a single-path power supply and a multi-path power supply, and is wide in application range.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of dimming control circuit, LED drive circuit and dimming LED, belong to power supply technical field. BACKGROUND

[0002] The existing dimming control circuit, generally all through the switch frequency of power MOS pipe connected in output, to adjust power output, realize the purpose of dimming or color modulation.When output short circuit occurs, power MOS pipe can be broken down and damaged due to the power of instantaneous or continuous output when short circuit is too large, so as to avoid the occurrence of the above phenomenon, the dimming control circuit on the market will be set short-circuit protection circuit to protect power device from being damaged when short circuit occurs.

[0003] At present, short-circuit protection scheme on the market is triggered by short-circuit protection through integrated control chip inherent detection, but the protection mode not only has the problem of slow response speed, and the cost is higher.

[0004] Therefore, it is necessary to improve the existing short-circuit protection scheme to solve the above problems. INVENTION CONTENTS

[0005] The utility model aims at providing a kind of dimming control circuit, the short-circuit protection circuit of the dimming control circuit is not only fast in response speed, cost is lower, and can be applied in single power supply and multiple power supply, and the scope of application is wide.

[0006] To achieve the above object, the utility model provides a kind of dimming control circuit, comprising:

[0007] Power supply circuit, its output end is connected with load;

[0008] Power control pipe, it is connected between power supply circuit and load;

[0009] Control drive circuit, its input end is connected with the output end of power supply circuit, output end is connected with the gate of power control pipe;And

[0010] Short-circuit protection circuit, including the zener diode connected with the output end of power supply circuit and the triode connected with the gate of power control pipe, zener diode is connected with triode, and is configured to when short circuit occurs in power supply circuit and / or load, triode is turned on by zener diode control, so that power control pipe is turned off.

[0011] Optionally, the negative pole of zener diode is connected with the output end of power supply circuit, the positive pole is connected with the base of triode, the collector of triode is connected with the gate of power control pipe, and the emitter is grounded.

[0012] Optionally, the short-circuit protection circuit further comprises a first current-limiting resistor, one end of the first current-limiting resistor is connected to the anode of the voltage stabilizing diode, and the other end of the first current-limiting resistor is connected to the base of the transistor.

[0013] Optionally, the short-circuit protection circuit further comprises a discharging resistor connected between the first current-limiting resistor and the transistor, one end of the discharging resistor is connected to the base of the transistor, and the other end of the discharging resistor is connected to the emitter of the transistor.

[0014] Optionally, a first diode is connected between the drain of the power control transistor and the power supply circuit, the anode of the first diode is connected to the drain of the power control transistor, and the cathode of the first diode is connected to the power supply circuit.

[0015] Optionally, the drain of the power control transistor is connected to the load, and the source of the power control transistor is connected to the ground, and a bleeder resistor is further connected between the gate and the source of the power control transistor.

[0016] Optionally, a second current-limiting resistor is connected between the output end of the control driving circuit and the gate of the power control transistor, and the input end of the bleeder resistor is connected to the output end of the second current-limiting resistor.

[0017] Optionally, the load is provided with multiple groups, the power control transistor and the short-circuit protection circuit are independently provided with multiple groups corresponding to the load, and the control driving circuit independently controls each group of power control transistors.

[0018] Optionally, a second diode corresponding to each group of power control transistors is connected between the drains of adjacent two groups of power control transistors, and the output ends of the two second diodes between the adjacent two groups of power control transistors are simultaneously connected to the voltage stabilizing diodes of the adjacent two groups of short-circuit protection circuits, so that when short circuit occurs in any one or more groups of loads, all the voltage stabilizing diodes and transistors are controlled to be turned on by the second diodes, and all the power control transistors are turned off.

[0019] The utility model also aims at providing a LED drive circuit, which has the advantages of fast response speed, low cost and wide application range.

[0020] To achieve the above-mentioned purpose, the utility model provides a LED drive circuit, which comprises the above-mentioned dimming control circuit.

[0021] The utility model also aims at providing a dimming LED, which has the advantages of fast response speed, low cost and wide application range.

[0022] To achieve the above-mentioned purpose, the utility model provides a dimming LED, which is driven by the above-mentioned LED drive circuit.

[0023] The beneficial effects of this invention are as follows: The dimming control circuit of this invention utilizes a Zener diode connected to the output terminal of the power supply circuit and a transistor connected to the gate of the power control transistor to form the main components of the short-circuit protection circuit. Thus, when a short circuit occurs in the power supply circuit and / or the load, the Zener diode can control the transistor to conduct, causing the power control transistor to turn off, preventing current from flowing through the power control transistor and causing damage under abnormal short-circuit conditions. Compared with existing technologies, the short-circuit protection circuit used in the dimming control circuit of this invention not only has a fast response speed and low cost, but can also be applied to both single-channel and multi-channel power supplies, making it widely applicable. Attached Figure Description

[0024] Figure 1 This is the circuit diagram of the dimming control circuit of this utility model.

[0025] Figure 2 yes Figure 1 The circuit diagram shown is a first embodiment of the dimming control circuit applied to a dual-power supply.

[0026] Figure 3 yes Figure 1 The circuit diagram shown is a second embodiment of the dimming control circuit applied to a dual-power supply.

[0027] Figure label:

[0028] 10 - Power supply circuit, 20 - Short circuit protection circuit. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1 As shown, this utility model discloses a dimming control circuit, including a power supply circuit 10, a power control transistor Q1, a control drive circuit (not shown), and a short-circuit protection circuit 20. The input terminal of the power supply circuit 10 is connected to the input voltage, and the output terminal is connected to the load. Optionally, the power supply circuit 10 can be an AC / DC circuit or a DC / DC circuit, used to convert the input AC power into DC power and the operating voltage, or to convert the input DC power into the operating voltage, to drive the load and control the normal operation of the drive circuit. In this utility model, the load is a lamp, preferably an LED.

[0031] The power control tube Q1 is connected in series between the output end of the power supply circuit 10 and the negative electrode of the load. The input end of the control driving circuit is connected with the output end of the power supply circuit 10, and the output end PWM_G is connected with the gate of the power control tube Q1, for generating the control signal of the power control tube Q1 according to the dimming control signal, and converting the control signal into the driving signal for driving the power control tube Q1 to act, so as to realize the control of the switching frequency of the power control tube Q1, and realize the adjustment of the power of the electric energy output to the load.

[0032] Optionally, the control driving circuit adopts the PWM dimming mode to control the brightness of the LED. Specifically, the pulse width modulation (PWM) is used to form the duty ratio by switching the on and off states of the current at high frequency, so as to control the light emitting amount of the LED. This mode has simple structure and saves power.

[0033] The short circuit protection circuit 20 comprises a Zener diode ZD2 connected with the output end of the power supply circuit 10 and a triode Q3 connected with the gate of the power control tube Q1. The Zener diode ZD2 is connected with the triode Q3, and is configured to control the triode Q3 to be turned on by the Zener diode ZD2 when the short circuit occurs in the power supply circuit 10 and / or the load, so as to make the power control tube Q1 quickly and urgently turn off.

[0034] Optionally, the negative electrode of the Zener diode ZD2 is connected with the output end of the power supply circuit 10. The positive electrode of the Zener diode ZD2 is connected with the base of the triode Q3. The collector of the triode Q3 is connected with the gate of the power control tube Q1, and the emitter is grounded. The Zener diode ZD2 is configured to be clamped and turned on when the short circuit occurs, and then the triode Q3 is turned on.

[0035] Optionally, the short circuit protection circuit 20 further comprises a first current limiting resistor R34 connected between the Zener diode ZD2 and the triode Q3. Optionally, one end of the first current limiting resistor R34 is connected with the positive electrode of the Zener diode ZD2, and the other end is connected with the base of the triode Q3, so as to limit the current flowing into the triode Q3, and prevent the triode Q3 from being burned out due to the excessive current.

[0036] Optionally, the short circuit protection circuit 20 further comprises a discharge resistor R36 connected between the first current limiting resistor R34 and the triode Q3. One end of the discharge resistor R36 is connected with the base of the triode Q3, and the other end is connected with the emitter of the triode Q3, so as to discharge the voltage between the base and the emitter of the triode Q3, and make the voltage between the base and the emitter less than the threshold voltage of the triode Q3, so as to protect the triode Q3.

[0037] The drain of the power control tube Q1 is connected with the power supply circuit 10, and the first diode D6 is connected between the drain of the power control tube Q1 and the power supply circuit 10.

[0038] The drain of the power control tube Q1 is connected with the load, and the source is grounded. The second current-limiting resistor R32 is connected between the output end PWM_G of the control driving circuit and the gate of the power control tube Q1. The bleeder resistor R17 is also connected between the gate and the source of the power control tube Q1. The input end of the bleeder resistor R17 is connected with the output end of the second current-limiting resistor R32. The second current-limiting resistor R32 is set so that the current from the output end PWM_G of the control driving circuit to the power control tube Q1 is appropriate. The bleeder resistor R17 is set to bleed the voltage between the gate and the source of the power control tube Q1, so that the voltage between the gate and the source is less than the threshold voltage of the power control tube Q1, and the false on action of the power control tube Q1 is reduced.

[0039] In combination Figure 1 As shown in the drawings, the working principle of the light control circuit of the utility model is that: when normally used, 24V and SGND provide constant 24V voltage or other voltage (not limited to a certain voltage value), when the output end PWM_G of the control driving circuit outputs high level, the power control tube Q1 is in the on state, at this time, LED1 and LED2 are connected in series and turned on, so that LED1 and LED2 are lighted; when abnormal short circuit occurs, the zener diode ZD2 is clamped and turned on, the zener voltage is 9V, the transistor Q3 is turned on to Vo-, and the gate of the power control tube Q1 is pulled to Vo-, at this time, the power control tube Q1 is in the off state, and no current flows, which avoids damage caused by current flowing through the power control tube Q1 under abnormal short circuit.

[0040] The above is a detailed description of the light control circuit under single power supply. Of course, in actual application, the light control circuit of the utility model can also be applied to multiple power supplies, that is, the load can be provided with multiple groups, such as two groups, three groups, four groups or more, at this time, the power control tube Q1 and the short circuit protection circuit 20 are also independently provided with multiple groups, such as two groups, three groups, four groups or more, and the control driving circuit independently controls each group of power control tubes Q1.

[0041] The following will take two embodiments of the light control circuit applied to double power supply as examples for illustration.

[0042] AsFigure 2 As shown, in the dual-power supply application mode, each group of power control transistors Q1 and Q2 is independently controlled by the control drive circuit, and each group of short-circuit protection circuits 20 is also independent of each other, so that the corresponding group of power control transistors Q1 and Q2 and the load (i.e. LED) can be turned off, which plays a role in separate protection.

[0043] During operation, both power supplies operate on the same principle as a single power supply, and if either power supply experiences a short circuit, it will not affect the normal operation of the other. In other words, the two power supplies do not interfere with or affect each other.

[0044] like Figure 3 As shown, in the dual-power supply application mode, a second diode corresponding to each power control transistor is connected between the drains of two adjacent power control transistors Q1 and Q2. The output terminals of the two second diodes between the two adjacent power control transistors Q1 and Q2 are simultaneously connected to the Zener diodes of the two adjacent short-circuit protection circuits 20. Thus, when a short circuit occurs in any one or more loads, the second diodes control all Zener diodes and transistors to conduct, causing all power control transistors Q1 and Q2 to be turned off.

[0045] Optionally, the two second diodes are diodes D9 and D10. Diode D9 is connected to the first power supply on the left and is used to conduct when a short circuit occurs in the first power supply. This clamps and conducts Zener diodes ZD2 and ZD3, turns on transistors Q3 and Q4 to Vo-, and pulls the gates of power control transistors Q1 and Q2 to Vo-. At this time, power control transistors Q1 and Q2 are both off, and no current flows through them. Diode D10 is connected to the second power supply on the right and is used to conduct when a short circuit occurs in the second power supply. This clamps and conducts Zener diodes ZD2 and ZD3, turns on transistors Q3 and Q4 to Vo-, and pulls the gates of power control transistors Q1 and Q2 to Vo-. At this time, power control transistors Q1 and Q2 are both off, and no current flows through them.

[0046] Figure 3The working principle is as follows: when normally used, 24V and SGND provide constant 24V voltage or other voltage (not limited to a certain voltage value), when the output end PWM_G of the control driving circuit outputs high level, the power control tubes Q1 and Q2 are in the conducting state, at this time, LED1 and LED2 are connected in series and turned on, LED3 and LED4 are connected in series and turned on, so that LED1-LED4 are lighted; when an abnormal short circuit occurs in a certain path, diode D9 or D10 is turned on, the voltage stabilizing diodes ZD2 and ZD3 are clamped and turned on, the triodes Q3 and Q4 are turned on to Vo-, and the gate of the power control tubes Q1 and Q2 is pulled to Vo-, at this time, the power control tubes Q1 and Q2 are in the off state, and no current flows, so as to avoid damage caused by current flowing through the power control tubes Q1 and Q2 in the abnormal short circuit condition.

[0047] It should be noted that: whether it is a certain single abnormality or a multi-path abnormality, the multi-path is turned off, and the whole dimming control circuit does not work, which plays a role in protecting the circuit.

[0048] Compared with the prior art, the dimming control circuit of the utility model can clamp the voltage stabilizing diode ZD2 to the voltage stabilizing state when an abnormal short circuit occurs, make the voltage stabilizing diode ZD2 and the triode Q3 successively conduct, then the triode Q3 rapidly pulls down the gate of the power control tube Q1, and makes the power control tube Q1 off, which plays a role in rapid protection.

[0049] The utility model also provides a LED driving circuit (not shown), the LED driving circuit includes above-mentioned dimming control circuit, has the function of fast drive, dimming, also has the advantages of fast response speed, low cost and wide application range.

[0050] The utility model also provides a dimming LED (not shown), the dimming LED is driven by the LED driving circuit, can realize fast dimming, also has the advantages of fast response speed, low cost and wide application range.

[0051] In conclusion, the dimming control circuit of the utility model uses the voltage stabilizing diode ZD2 connected with the output end of the power supply circuit 10 and the triode Q3 connected with the gate of the power control tube Q1 to constitute the main components of the short circuit protection circuit 20, so that when the power supply circuit 10 and / or load is short-circuited, the triode Q3 can be turned on by the voltage stabilizing diode ZD2, and the power control tube Q1 is turned off, so as to avoid damage caused by current flowing through the power control tube Q1 in the abnormal short circuit state. Compared with the prior art, the short circuit protection circuit 20 used in the dimming control circuit of the utility model not only has fast response speed, low cost and high reliability, but also has good practicability in low value schemes, and can be applied in single power supply and multi-power supply, so it has wide application range.

[0052] The above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A dimming control circuit, characterized in that, include: The power supply circuit (10) has its output terminal connected to the load; A power control transistor is connected between the power supply circuit (10) and the load; The control drive circuit has its input terminal connected to the output terminal of the power supply circuit (10) and its output terminal connected to the gate of the power control transistor. as well as The short-circuit protection circuit (20) includes a Zener diode connected to the output terminal of the power supply circuit (10) and a transistor connected to the gate of the power control transistor. The Zener diode is connected to the transistor and is configured to control the transistor to turn on and turn off the power control transistor when a short circuit occurs in the power supply circuit (10) and / or the load.

2. The dimming control circuit according to claim 1, characterized in that, The negative terminal of the Zener diode is connected to the output terminal of the power supply circuit (10), the positive terminal is connected to the base of the transistor, the collector of the transistor is connected to the gate of the power control transistor, and the emitter is grounded.

3. The dimming control circuit according to claim 1, characterized in that, The short-circuit protection circuit (20) further includes a first current-limiting resistor, one end of which is connected to the positive terminal of the Zener diode and the other end of which is connected to the base of the transistor.

4. The dimming control circuit according to claim 3, characterized in that, The short-circuit protection circuit (20) further includes a discharge resistor connected between the first current-limiting resistor and the transistor, with one end of the discharge resistor connected to the base of the transistor and the other end connected to the emitter of the transistor.

5. The dimming control circuit according to claim 1, characterized in that, A first diode is connected between the drain of the power control transistor and the power supply circuit (10). The positive terminal of the first diode is connected to the drain of the power control transistor, and the negative terminal of the first diode is connected to the power supply circuit (10).

6. The dimming control circuit according to claim 1, characterized in that, The drain of the power control transistor is connected to the load, and the source is grounded. A bleed resistor is also connected between the gate and the source of the power control transistor.

7. The dimming control circuit according to claim 6, characterized in that, A second current-limiting resistor is connected between the output terminal of the control drive circuit and the gate of the power control transistor, and the input terminal of the discharge resistor is connected to the output terminal of the second current-limiting resistor.

8. The dimming control circuit according to claim 1, characterized in that, The load is configured in multiple groups, and the power control transistor and the short-circuit protection circuit (20) are configured in multiple groups independently for each load. The control drive circuit independently controls each group of the power control transistor.

9. The dimming control circuit according to claim 8, characterized in that, A second diode corresponding to each power control transistor is connected between the drains of two adjacent power control transistors. The output terminals of the two second diodes between two adjacent power control transistors are simultaneously connected to the Zener diodes of the two adjacent short-circuit protection circuits (20). When any one or more loads are short-circuited, the second diodes control all the Zener diodes and transistors to conduct, so that all power control transistors are turned off.

10. An LED driving circuit, characterized in that, The dimming control circuit includes any one of claims 1-9.

11. A dimming LED, characterized in that, Driven by the LED driving circuit as described in claim 10.

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