Over-temperature protection circuit

Abstract

The utility model relates to the technical field of electronic circuits, in particular to an over-temperature protection circuit, which is characterized by comprising a rectifying circuit, a filter circuit, a chip U1, a metal oxide semiconductor (MOS) tube Q1 driving control network, an intensifier circuit and an adjusting circuit. Wherein the rectifying circuit is used for converting input alternating current into direct current; the filter circuit is used for removing electromagnetic interference in the direct current converted by the rectifying circuit; the chip U1 is used for driving the on and off of the MOS tube Q1; the MOS tube Q1 drives the control network and is used for controlling energy storage and discharge of the energy storage inductor T1; the enhancement circuit is used for enhancing the driving capability of the MOS tube Q1; and the adjusting circuit is used for controlling the output power and temperature of the driving power supply. According to the over-temperature protection circuit provided by the utility model, temperature protection points can be conveniently set by adjusting parameters of components, and the reliability of the components is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, and more specifically, to an over-temperature protection circuit. Background Art

[0002] In light source products such as bulbs and tubes, power supplies are usually built in. If the power of the light source product is large and the volume of the power cavity is small, the heat dissipation effect is poor, which will cause the temperature of the components in the drive to rise, especially power components such as chips, MOS tubes, and diodes, which will have an adverse effect on the service life of the product. Chips in the prior art usually have an over-temperature protection function. When the chip temperature exceeds the over-temperature protection point, the current is reduced to ensure the performance and life of the product.

[0003] However, the over-temperature protection point of the chip is a fixed value, which is not convenient to adjust. In addition, the over-temperature protection of the chip can only improve the temperature of the chip to a certain extent, but cannot make corresponding improvements to the temperature of its supporting MOS tubes, diodes and other power components. Utility Model Content

[0004] In view of the deficiencies in the prior art, the purpose of the utility model is to provide an over-temperature protection circuit, which has the advantage of being easy to adjust the temperature of power components.

[0005] The above technical purpose of the utility model is achieved through the following technical solutions: an over-temperature protection circuit, comprising:

[0006] Rectifier circuit, used to convert input AC power into DC power;

[0007] A filter circuit, used to remove electromagnetic interference in the direct current converted by the rectifier circuit;

[0008] Chip U1 is used to drive the MOS tube Q1 to turn on and off;

[0009] MOS tube Q1 drives the control network to control the energy storage and discharge of the energy storage inductor T1;

[0010] An enhancement circuit, used to increase the driving capability of the MOS tube Q1;

[0011] The regulating circuit is used to control the output power and temperature of the driving power supply.

[0012] In one embodiment, the rectifier circuit includes an industrial mode magnetic ring LF1, a capacitor CX1 and a bridge rectifier module BD1, and the alternating current passes through the industrial mode magnetic ring LF1, the capacitor CX1 and the bridge rectifier module BD1 in sequence to be output as the direct current.

[0013] In one embodiment, the filter circuit includes a capacitor C1, a capacitor C2 and an inductor L1, wherein the capacitor C1 and the capacitor C2 are connected in parallel, and the inductor L1 is arranged between the capacitor C1 and the capacitor C2.

[0014] In one embodiment, the filter circuit further includes a chip capacitor C6 and a chip capacitor C7, the chip capacitor C6 is connected in series with the inductor L1, and the chip capacitor C6 is connected in parallel with the chip capacitor C7.

[0015] In one embodiment, the MOS tube Q1 drive control network includes a resistor R6, a resistor R2, a resistor R3 and a diode D2, one end of the resistor R6 is connected to the GATE of the chip U1, and the other end is connected to the diode D2, one end of the resistor R2 is connected between the resistor R6 and the diode D2, and the other end is connected between the resistor R3 and the diode D2.

[0016] In one embodiment, a sampling resistor RS1 and a sampling resistor RS2 are further connected to the CS pin of the chip U1 for monitoring the output current of the chip U1.

[0017] In one embodiment, the enhancement circuit includes a capacitor C3, a capacitor C5, a resistor R15, a resistor R16, a diode D3, a diode Z1 and a transistor Q2;

[0018] Among them, one end of the capacitor C3 is grounded, and the other end is connected in series with the capacitor C5. The resistor R15 and the diode D3 are connected in series between the capacitor C3 and the capacitor C5. One end of the diode Z1 is grounded, and the other end is connected between the diode D3 and the resistor R15. One end of the resistor R16 is connected to the transistor Q2, and the other end is connected between the capacitor C3 and the diode D3.

[0019] In one embodiment, the regulating circuit includes a resistor R5, a resistor R11 and a resistor R12, one end of the resistor R12 is grounded, and the other end is connected to the RTH pin of the chip U1, one end of the resistor R11 is grounded, and the other end is connected in series with the resistor R5, and the resistor R5 is connected to the RTH pin of the chip U1.

[0020] In one embodiment, it also includes a resistor R8, a resistor R9, a resistor R10 and a capacitor C4, the resistor R9, the resistor R10 and the resistor R8 are connected in series in sequence, the capacitor C4 is connected in parallel with the resistor R9, the GND pin of the chip U1 is connected to the resistor R9 and the capacitor C4, and the OVP pin of the chip U1 is connected between the resistor R9 and the resistor R10.

[0021] In one embodiment, a circuit output module is further included, and the circuit output includes a diode D1, an electrolytic capacitor EC1 and a resistor R4, so as to provide the stable direct current.

[0022] The above-mentioned over-temperature protection circuit has the following beneficial effects:

[0023] First, by adjusting the parameters of components, the temperature protection point can be conveniently set to improve the reliability of components;

[0024] Secondly, the circuit network composed of capacitors C3, C5, resistors R15, R16, diodes D3, Z1 and transistor Q2 increases the driving capability of MOS tube Q1, reduces the loss of MOS tube, reduces the temperature of MOS tube, thereby reducing the ambient temperature of the entire cavity, and optimizes the temperature of other components;

[0025] Third, the RTH pin of chip U1 is also the over-temperature protection adjustment pin. Resistors R5, R11, and R12 are added to form an over-temperature protection circuit. The resistance values ​​of resistors R5, R11, and R12 can be set arbitrarily according to actual needs. When the driving power supply is overheated, the output current is gradually reduced, thereby controlling the output power and temperature rise, so that the power supply temperature is maintained at the set value to improve the reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the circuit in this embodiment. DETAILED DESCRIPTION

[0027] The utility model is described in detail below in conjunction with the accompanying drawings and embodiments.

[0028] An over-temperature protection circuit, such as Figure 1 As shown, it includes a rectifier circuit, a filter circuit, a chip U1, a MOS tube Q1 drive control network, an enhancement circuit and a regulation circuit;

[0029] in,

[0030] Rectifier circuit, used to convert input AC power into DC power;

[0031] A filter circuit is used to remove electromagnetic interference from the direct current converted by the rectifier circuit;

[0032] Chip U1 is used to drive the MOS tube Q1 to turn on and off;

[0033] MOS tube Q1 drives the control network to control the energy storage and discharge of the energy storage inductor T1;

[0034] Enhancement circuit, used to increase the driving capability of MOS tube Q1;

[0035] The regulating circuit is used to control the output power and temperature of the driving power supply.

[0036] Specifically, the rectifier circuit includes an industrial mode magnetic ring LF1, a capacitor CX1 and a bridge rectifier module BD1. The alternating current passes through the industrial mode magnetic ring LF1, the capacitor CX1 and the bridge rectifier module BD1 in sequence, and is output as direct current, thereby realizing the conversion between alternating current and direct current and providing energy for subsequent components.

[0037] Specifically, the filter circuit includes a capacitor C1, a capacitor C2 and an inductor L1, wherein the capacitor C1 is connected in parallel with the capacitor C2, and the inductor L1 is arranged between the capacitor C1 and the capacitor C2;

[0038] Inductor L1 adopts I-shaped inductor to eliminate filtering interference in the circuit;

[0039] Furthermore, the filter circuit also includes a chip capacitor C6 and a chip capacitor C7. The chip capacitor C6 is connected in series with the inductor L1. The chip capacitor C6 and the chip capacitor C7 are connected in parallel. The chip capacitor C6 and the chip capacitor C7 can effectively absorb circuit interference and reduce EMI.

[0040] Specifically, the MOS tube Q1 drive control network includes a resistor R6, a resistor R2, a resistor R3 and a diode D2, which is used to store and discharge energy in the energy storage inductor T1 to provide energy to the load; one end of the resistor R6 is connected to the GATE of the chip U1, and the other end is connected to the diode D2; one end of the resistor R2 is connected between the resistor R6 and the diode D2, and the other end is connected between the resistor R3 and the diode D2.

[0041] Furthermore, the CS pin of the chip U1 is also connected to a sampling resistor RS1 and a sampling resistor RS2 for monitoring the output current of the chip U1, and realizing a constant current output by over-detecting the current feedback passing through the sampling resistor RS1 and the sampling resistor RS2;

[0042] Specifically, the enhancement circuit includes capacitor C3, capacitor C5, resistor R15, resistor R16, diode D3, diode Z1 and transistor Q2;

[0043] Among them, one end of capacitor C3 is grounded, and the other end is connected in series with capacitor C5. Resistor R15 and diode D3 are connected in series between capacitor C3 and capacitor C5. One end of diode Z1 is grounded, and the other end is connected between diode D3 and resistor R15. One end of resistor R16 is connected to transistor Q2, and the other end is connected between capacitor C3 and diode D3.

[0044] The enhancement circuit increases the driving capability of the MOS tube Q1, reduces the operating loss of the MOS tube Q1, and reduces the operating temperature of the MOS tube Q1. As a key power device, the MOS tube Q1 plays a vital role in the environment of the entire cavity. When the temperature of the MOS tube Q1 decreases, the ambient temperature in the cavity also decreases, and the temperature of other components is also optimized.

[0045] Furthermore, the regulating circuit includes resistor R5, resistor R11 and resistor R12, one end of resistor R12 is grounded, and the other end is connected to the RTH pin of chip U1, one end of resistor R11 is grounded, and the other end is connected in series with resistor R5, and resistor R5 is connected to the RTH pin of chip U1.

[0046] The resistance values ​​of resistors R5, R11 and R12 can be set arbitrarily according to actual needs. When the driving power supply is overheated, the output current is gradually reduced to control the output power and temperature rise, so that the power supply temperature is maintained at the set value to improve the reliability of the system.

[0047] Furthermore, it also includes a resistor R8, a resistor R9, a resistor R10 and a capacitor C4. The resistor R9, the resistor R10 and the resistor R8 are connected in series in sequence. The capacitor C4 is connected in parallel with the resistor R9. The GND pin of the chip U1 is connected to the resistor R9 and the capacitor C4. The OVP pin of the chip U1 is connected between the resistor R9 and the resistor R10.

[0048] The no-load voltage can be set by changing the resistance values ​​of resistors R8, R9 and R10 to improve the stability of the equipment when it is running at no load.

[0049] Preferably, a circuit output module is also included, and the circuit output includes a diode D1, an electrolytic capacitor EC1 and a resistor R4, so as to provide stable direct current.

[0050] The above-mentioned embodiments only express several implementation methods of the utility model, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the utility model. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the utility model, and these all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. An over-temperature protection circuit, characterized in that: include: Rectifier circuit, used to convert input AC power into DC power; A filter circuit, used to remove electromagnetic interference in the direct current converted by the rectifier circuit; Chip U1 is used to drive the MOS tube Q1 to turn on and off; MOS tube Q1 drives the control network to control the energy storage and discharge of the energy storage inductor T1; An enhancement circuit, used to increase the driving capability of the MOS tube Q1; The regulating circuit is used to control the output power and temperature of the driving power supply.

2. An over-temperature protection circuit according to claim 1, characterized in that: The rectifier circuit includes an industrial mode magnetic ring LF1, a capacitor CX1 and a bridge rectifier module BD1. The alternating current passes through the industrial mode magnetic ring LF1, the capacitor CX1 and the bridge rectifier module BD1 in sequence and is output as the direct current.

3. An over-temperature protection circuit according to claim 2, characterized in that: The filter circuit includes a capacitor C1, a capacitor C2 and an inductor L1, wherein the capacitor C1 is connected in parallel with the capacitor C2, and the inductor L1 is arranged between the capacitor C1 and the capacitor C2.

4. The over-temperature protection circuit according to claim 3, characterized in that: The filter circuit further includes a patch capacitor C6 and a patch capacitor C7. The patch capacitor C6 is connected in series with the inductor L1, and the patch capacitor C6 is connected in parallel with the patch capacitor C7.

5. An over-temperature protection circuit according to claim 4, characterized in that: The MOS tube Q1 drive control network includes a resistor R6, a resistor R2, a resistor R3 and a diode D2. One end of the resistor R6 is connected to the GATE of the chip U1, and the other end is connected to the diode D2. One end of the resistor R2 is connected between the resistor R6 and the diode D2, and the other end is connected between the resistor R3 and the diode D2.

6. An over-temperature protection circuit according to claim 5, characterized in that: The CS pin of the chip U1 is also connected to a sampling resistor RS1 and a sampling resistor RS2 for monitoring the output current of the chip U1.

7. An over-temperature protection circuit according to claim 6, characterized in that: The enhancement circuit includes a capacitor C3, a capacitor C5, a resistor R15, a resistor R16, a diode D3, a diode Z1 and a transistor Q2; Among them, one end of the capacitor C3 is grounded, and the other end is connected in series with the capacitor C5. The resistor R15 and the diode D3 are connected in series between the capacitor C3 and the capacitor C5. One end of the diode Z1 is grounded, and the other end is connected between the diode D3 and the resistor R15. One end of the resistor R16 is connected to the transistor Q2, and the other end is connected between the capacitor C3 and the diode D3.

8. An over-temperature protection circuit according to claim 7, characterized in that: The regulating circuit includes a resistor R5, a resistor R11 and a resistor R12, one end of the resistor R12 is grounded, and the other end is connected to the RTH pin of the chip U1, one end of the resistor R11 is grounded, and the other end is connected in series with the resistor R5, and the resistor R5 is connected to the RTH pin of the chip U1.

9. An over-temperature protection circuit according to claim 8, characterized in that: It also includes a resistor R8, a resistor R9, a resistor R10 and a capacitor C4, wherein the resistor R9, the resistor R10 and the resistor R8 are connected in series in sequence, the capacitor C4 is connected in parallel with the resistor R9, the GND pin of the chip U1 is connected with the resistor R9 and the capacitor C4, and the OVP pin of the chip U1 is connected between the resistor R9 and the resistor R10.

10. An over-temperature protection circuit according to claim 9, characterized in that: It also includes a circuit output module, wherein the circuit output includes a diode D1, an electrolytic capacitor EC1 and a resistor R4, for providing the stable direct current.

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