Low-cost dimming and color temperature adjusting circuit with short-circuit protection

Abstract

The utility model discloses a low-cost dimming and color temperature adjusting circuit with short circuit protection, which comprises an optocoupler U1, a signal inversion circuit, an MOS tube Q3, an MOS tube Q4, an LED1-and an LED2-, the optocoupler U1 receives a PWM signal and outputs a color temperature adjusting signal, the input end of the signal inversion circuit is connected with the optocoupler U1 to receive the color temperature adjusting signal, the output end of the signal inversion circuit is connected with the MOS tube Q3, the MOS tube Q3 is connected with the LED2-to adjust the color temperature of the LED2-, and the output end of the signal inversion circuit is connected with the MOS tube Q4 to adjust the color temperature of the LED2-. The MOS tube Q3 is connected with the MOS tube Q4, and the MOS tube Q4 is connected with the LED 1-to adjust the color temperature of the LED 1-. The circuit further comprises a first short-circuit protection circuit and a second short-circuit protection circuit, the first short-circuit protection circuit is connected with the MOS tube Q3, and the second short-circuit protection circuit is connected with the MOS tube Q4. According to the utility model, three major pain points of a color temperature adjusting circuit are solved in a low-cost mode, namely, the problems of high cost of a BUCK scheme, efficiency loss and heating of a resistance scheme, and damage caused by short circuit of an MOS (Metal Oxide Semiconductor) scheme.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of electronic circuit application, concretely is a low cost light modulation and color temperature modulation circuit with short circuit protection. BACKGROUND

[0002] With the more and more mature of LED lighting industry, people not only pursue the adjustment of illumination brightness, but also need to adjust color temperature to meet the pursuit of people to the quality of life, the current market color temperature modulation scheme has different degrees of shortcomings, such as by adding resistance in the lamp string, the efficiency loss of this way is big and the heat is still more serious, another way is that each string of lamp corresponds to a BUCK circuit, the current size of two lamp string lamp beads is adjusted to realize color temperature modulation, but this way is high in cost, which is not conducive to market promotion. UTILITY MODEL CONTENTS

[0003] To solve the defects of the prior art, the utility model provides a low cost light modulation and color temperature modulation circuit with short circuit protection, the utility model discloses a low cost way to solve the three major pain points of color temperature modulation circuit, one is the high cost of BUCK scheme, two is the efficiency loss and heating problem of resistance scheme, three is the short circuit damage problem of MOS scheme.

[0004] To realize the above technical purpose, the utility model adopts the following technical scheme: a low cost light modulation and color temperature modulation circuit with short circuit protection, including photoelectric coupler U1, signal inversion circuit, MOS tube Q3, MOS tube Q4, LED1-, LED2-, the photoelectric coupler U1 receives PWM signal and outputs color temperature modulation signal, the input end of signal inversion circuit is connected with the photoelectric coupler U1 receiving color temperature modulation signal, and the output end is connected with MOS tube Q3, MOS tube Q3 is connected with LED2- to adjust the color temperature of LED2-, MOS tube Q3 is connected with MOS tube Q4 simultaneously, and MOS tube Q4 is connected with LED1- to adjust the color temperature of LED1-;

[0005] Still include first road short circuit protection circuit, second road short circuit protection circuit, the first road short circuit protection circuit is connected with MOS tube Q3, and the second road short circuit protection circuit is connected with MOS tube Q4.

[0006] Further, the signal inversion circuit includes resistance R2, resistance R3, resistance R4, resistance R5, resistance R6, capacitor C1, MOS tube Q2, one end of resistance R2 and one end of resistance R3 are commonly connected with the photoelectric coupler U1, the other end of resistance R2 is connected with capacitor C1 and the gate of MOS tube Q2, capacitor C1 is grounded, the source of MOS tube Q2 is grounded, the drain of MOS tube Q2 is connected with resistance R4 and resistance R5, resistance R4 is connected with resistance R3 and linear voltage stabilizing circuit, resistance R5 is connected with resistance R6, the gate of MOS tube Q3 and the first road short circuit protection circuit.

[0007] Further, the first short-circuit protection circuit comprises resistance R9, resistance R8, resistance R7, capacitor C2, diode D3, triode Q5, one end of the resistance R9 is grounded, the other end is connected to the source of the MOS Q3 and the resistance R8, the drain of the MOS Q3 is connected to LED2-, capacitor C2, diode D3, resistance R7, the capacitor C2 is grounded, the diode D3 is grounded, the resistance R7 and the resistance R8 are commonly connected to the base of the triode Q5, the emitter of the triode Q5 is grounded, and the collector of the triode Q5 is connected to the gate of the MOS Q3.

[0008] Further, the gate of the MOS Q4 is connected to resistance R10, resistance R11 and diode D5, the resistance R10 is connected to a linear voltage stabilizing circuit, the resistance R11 is grounded, the diode D5 is connected to the resistance R9, and the resistance R9 is connected to the drain of the MOS Q3; the drain of the MOS Q4 is connected to LED1-.

[0009] Further, the second short-circuit protection circuit comprises resistance R12, resistance R14, resistance R13, capacitor C3, diode D4, triode Q6, one end of the resistance R12 is grounded, the other end is connected to the source of the MOS Q4 and the resistance R14, the drain of the MOS Q3 is connected to LED1-, capacitor C3, diode D4, resistance R13, the capacitor C3 is grounded, the diode D4 is grounded, the resistance R13 and the resistance R14 are commonly connected to the base of the triode Q6, the emitter of the triode Q6 is grounded, and the collector of the triode Q6 is connected to the gate of the MOS Q4.

[0010] Further, the linear voltage stabilizing circuit comprises triode Q1, resistance R1, voltage stabilizing tube ZD1, diode D1, the collector of the triode Q1 is connected to LED+, the base of the triode Q1 is connected to the voltage stabilizing tube ZD1, the voltage stabilizing tube ZD1 is connected to LED-, the base of the triode Q1 is also connected to the resistance R1 and the diode D1, the resistance R1 is connected to the collector of the triode Q1, the diode D1 is connected to the emitter of the triode Q1, and the emitter of the triode Q1 is also connected to the resistance R10.

[0011] Further, the light coupling U2 is also included, which receives a PWM signal and outputs a dimming signal.

[0012] In summary, the utility model has the following technical effects:

[0013] The utility model discloses a color temperature adjusting mode is on every string of lamp pearl adds the MOS pipe, controls the duty cycle of MOS to reach the purpose of adjusting color temperature, and this mode can solve the efficiency and heating problem of resistance mode, and the cost is also much lower than BUCK circuit, is a kind of more balanced color temperature adjusting mode, in addition, this mode is very easy to damage MOS when LED short circuit, but short circuit can not be avoided when the customer uses in production process, the utility model solves this problem by short circuit protection circuit, and cost is extremely low, conducive to mass production.

[0014] In addition, the utility model discloses a color temperature adjusting signal is isolated with output simultaneously, and color temperature can be adjusted with only one PWM signal, and only one 8-bit MCU or dimming chip can be used to realize dimming and color temperature adjustment, which greatly reduces the cost. DRAWINGS

[0015] Figure 1 It is a low-cost dimming and color temperature adjusting circuit schematic diagram provided by the utility model embodiment. DETAILED DESCRIPTION

[0016] The utility model will be further described in detail below in combination with drawings.

[0017] The embodiment is only an explanation of the utility model, and it is not a limitation of the utility model, and those skilled in the art can make modifications without creative contribution after reading the specification, but as long as it is within the scope of the utility model claims, it is protected by the patent law.

[0018] In the description of the utility model, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, structure and operation, so it cannot be understood as a limitation of the utility model.

[0019] In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first" and "second" can explicitly or implicitly include one or more features. In the description of the utility model, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0020] In the present application, unless otherwise expressly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0021] In the present application, unless otherwise expressly specified and limited, the first feature is "on" or "under" the second feature. The first and second features can be in direct contact, or the first and second features can be in indirect contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0022] Embodiment:

[0023] As shown in Figure 1 A low-cost dimming and color temperature adjusting circuit with short-circuit protection includes optocoupler U1, signal inversion circuit 2, MOS tube Q3, MOS tube Q4, LED1-, LED2-, the optocoupler U1 receives a PWM signal and outputs a color temperature adjusting signal, the input end of the signal inversion circuit 2 is connected to the optocoupler U1 receiving the color temperature adjusting signal, and the output end is connected to the MOS tube Q3, the MOS tube Q3 is connected to the LED2- to adjust the color temperature of the LED2-, and the MOS tube Q3 is connected to the MOS tube Q4 at the same time, and the MOS tube Q4 is connected to the LED1- to adjust the color temperature of the LED1-;

[0024] It also includes a first short-circuit protection circuit 3 and a second short-circuit protection circuit 4, the first short-circuit protection circuit 3 is connected to the MOS tube Q3, and the second short-circuit protection circuit 4 is connected to the MOS tube Q4;

[0025] The signal inversion circuit 2 comprises resistors R2, R3, R4, R5, R6, capacitor C1, MOS tube Q2, one end of the resistor R2 and one end of the resistor R3 are commonly connected to the optocoupler U1, the other end of the resistor R2 is connected to the capacitor C1 and the gate of the MOS tube Q2, the capacitor C1 is grounded, the source of the MOS tube Q2 is grounded, the drain of the MOS tube Q2 is connected to the resistor R4 and the resistor R5, the resistor R4 is connected to the resistor R3 and the linear voltage stabilizing circuit, the resistor R5 is connected to the resistor R6, the gate of the MOS tube Q3 and the first short circuit protection circuit 3. The signal inversion circuit 2 reverses the PWM signal sent by the MCU or the light and color temperature adjusting signal and sends it to Q3 for driving Q3, and Q3 adjusts the duty cycle of one of the light beads to adjust the color temperature.

[0026] The first short circuit protection circuit 3 comprises resistors R9, R8, R7, capacitor C2, diode D3, and triode Q5, one end of the resistor R9 is grounded, the other end is connected to the source of the MOS tube Q3 and the resistor R8, the drain of the MOS tube Q3 is connected to LED2-, capacitor C2, diode D3, and resistor R7, the capacitor C2 is grounded, the diode D3 is grounded, the resistor R7 and the resistor R8 are commonly connected to the base of the triode Q5, the emitter of the triode Q5 is grounded, and the collector of the triode Q5 is connected to the gate of the MOS tube Q3. The first short circuit protection circuit 3 protects Q3 from being damaged due to output short circuit.

[0027] The gate of the MOS tube Q4 is connected to the resistor R10, the resistor R11, and the diode D5, the resistor R10 is connected to the linear voltage stabilizing circuit, the resistor R11 is grounded, the diode D5 is connected to the resistor R9, and the resistor R9 is connected to the drain of the MOS tube Q3; the drain of the MOS tube Q4 is connected to LED1-. R10 and R11 provide a driving voltage for Q4, and R9 and D5 provide another color temperature adjusting signal.

[0028] The second short circuit protection circuit 4 comprises resistors R12, R14, R13, capacitor C3, diode D4, and triode Q6, one end of the resistor R12 is grounded, the other end is connected to the source of the MOS tube Q4 and the resistor R14, the drain of the MOS tube Q3 is connected to LED1-, capacitor C3, diode D4, and resistor R13, the capacitor C3 is grounded, the diode D4 is grounded, the resistor R13 and the resistor R14 are commonly connected to the base of the triode Q6, the emitter of the triode Q6 is grounded, and the collector of the triode Q6 is connected to the gate of the MOS tube Q4. The second short circuit protection circuit 4 protects Q4 from being damaged due to output short circuit.

[0029] The linear voltage stabilizing circuit comprises a triode Q1, a resistor R1, a voltage stabilizing tube ZD1 and a diode D1, the collector of the triode Q1 is connected with the LED+, the base of the triode Q1 is connected with the voltage stabilizing tube ZD1, the voltage stabilizing tube ZD1 is connected with the LED-, the base of the triode Q1 is also connected with the resistor R1 and the diode D1, the resistor R1 is connected with the collector of the triode Q1, the diode D1 is connected with the emitter of the triode Q1, and the emitter of the triode Q1 is also connected with the resistor R10.

[0030] The light coupling U2 receives a PWM signal and outputs a dimming signal, and the dimming signal is sent to a dimming power circuit for dimming.

[0031] The light coupling U2 and the light coupling U1 are connected to an MCU or a dimming and color temperature signal circuit.

[0032] The LED output voltage is passed through the linear voltage stabilizing circuit composed of Q1, R1, ZD1 and D1 to provide a stable power supply voltage for the color temperature adjusting circuit, the MCU or the dimming chip outputs a PWM signal which is isolated by the light coupling U1 to provide a color temperature adjusting signal, the PWM signal is inverted through R2, R3, C1, Q2, R4, R5 and R6, and then Q3 is driven to adjust the duty cycle of one of the light beads; R9, D3, R7, R8 and Q5, C2 form a short circuit protection circuit to protect Q3 from being damaged due to output short circuit; the other color temperature adjusting signal is provided by R9 and D5, when Q3 is turned on, the G-S voltage of Q4 is pulled down to be cut off, R10 and R11 provide a driving voltage for Q4, so that Q3 and Q4 are alternately and complementarily turned on to achieve the purpose of adjusting the color temperature, different color temperatures can be adjusted to different duty cycles to achieve the purpose, R12, D4, R13, R14 and Q6, C3 form a short circuit protection circuit to protect Q4 from being damaged due to output short circuit; the MCU or the dimming chip outputs another PWM signal which is isolated by the light coupling U2 to provide a dimming signal to the main power circuit for dimming.

[0033] The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form, and any simple modification, equivalent change and modification according to the technical essence of the utility model are within the scope of the utility model technical scheme.

Claims

1. A low-cost dimming and color temperature adjustment circuit with short-circuit protection, characterized in that: Includes optocoupler U1, signal inversion circuit (2), MOS transistor Q3, MOS transistor Q4, LED1-, LED2-. The optocoupler U1 receives the PWM signal and outputs the color temperature adjustment signal. The input terminal of the signal inversion circuit (2) is connected to the optocoupler U1 to receive the color temperature adjustment signal, and the output terminal is connected to the MOS transistor Q3. The MOS transistor Q3 is connected to LED2- to adjust the color temperature of LED2-. The MOS transistor Q3 is also connected to the MOS transistor Q4. The MOS transistor Q4 is connected to LED1- to adjust the color temperature of LED1-. It also includes a first short-circuit protection circuit (3) and a second short-circuit protection circuit (4). The first short-circuit protection circuit (3) is connected to MOSFET Q3, and the second short-circuit protection circuit (4) is connected to MOSFET Q4.

2. The low-cost dimming and color temperature adjustment circuit with short-circuit protection according to claim 1, characterized in that: The signal inversion circuit (2) includes resistors R2, R3, R4, R5, and R6, capacitor C1, and MOSFET Q2. One end of resistor R2 and one end of resistor R3 are connected to the optocoupler U1. The other end of resistor R2 is connected to capacitor C1 and the gate of MOSFET Q2. Capacitor C1 is grounded, the source of MOSFET Q2 is grounded, and the drain of MOSFET Q2 is connected to resistors R4 and R5. Resistor R4 is connected to resistor R3 and the linear voltage regulator circuit. Resistor R5 is connected to resistor R6, the gate of MOSFET Q3, and the first short-circuit protection circuit (3).

3. The low-cost dimming and color temperature adjustment circuit with short-circuit protection according to claim 1, characterized in that: The first short-circuit protection circuit (3) includes resistors R9, R8, R7, capacitor C2, diode D3, and transistor Q5. One end of resistor R9 is grounded, and the other end is connected to the source of MOSFET Q3 and resistor R8. The drain of MOSFET Q3 is connected to LED2-, capacitor C2, diode D3, and resistor R7. Capacitor C2 is grounded, diode D3 is grounded, resistors R7 and R8 are connected to the base of transistor Q5, the emitter of transistor Q5 is grounded, and the collector of transistor Q5 is connected to the gate of MOSFET Q3.

4. A low-cost dimming and color temperature adjustment circuit with short-circuit protection according to claim 1, characterized in that: The gate of the MOSFET Q4 is connected to resistor R10, resistor R11, and diode D5. Resistor R10 is connected to a linear voltage regulator circuit, resistor R11 is grounded, diode D5 is connected to resistor R9, and resistor R9 is connected to the drain of the MOSFET Q3. The drain of the MOSFET Q4 is connected to LED1-.

5. A low-cost dimming and color temperature adjustment circuit with short-circuit protection according to claim 1, characterized in that: The second short-circuit protection circuit (4) includes resistors R12, R14, R13, capacitor C3, diode D4, and transistor Q6. One end of resistor R12 is grounded, and the other end is connected to the source of MOSFET Q4 and resistor R14. The drain of MOSFET Q3 is connected to LED1-, capacitor C3, diode D4, and resistor R13. Capacitor C3 is grounded, diode D4 is grounded, resistors R13 and R14 are connected to the base of transistor Q6, the emitter of transistor Q6 is grounded, and the collector of transistor Q6 is connected to the gate of MOSFET Q4.

6. A low-cost dimming and color temperature adjustment circuit with short-circuit protection according to claim 1, characterized in that: It also includes a linear voltage regulator circuit, which includes a transistor Q1, a resistor R1, a Zener diode ZD1, and a diode D1. The collector of transistor Q1 is connected to LED+, the base of transistor Q1 is connected to Zener diode ZD1, Zener diode ZD1 is connected to LED-, the base of transistor Q1 is also connected to resistor R1 and diode D1, resistor R1 is connected to the collector of transistor Q1, diode D1 is connected to the emitter of transistor Q1, and the emitter of transistor Q1 is also connected to resistor R10.

7. A low-cost dimming and color temperature adjustment circuit with short-circuit protection according to claim 1, characterized in that: It also includes optocoupler U2, which receives PWM signals and outputs dimming signals.

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