Over-temperature protection control circuit and power supply equipment

Abstract

The utility model discloses an over-temperature protection control circuit and power supply equipment, the over-temperature protection control circuit comprises a reference circuit and a temperature detection circuit, the output end of the reference circuit is connected to the input end of the temperature detection circuit; the temperature detection circuit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a first controllable precision voltage stabilization source, a first switch tube, a second switch tube, a first capacitor and a thermistor. According to the utility model, the thermistor is adopted in the temperature detection circuit to replace a temperature switch in the traditional scheme, so that the control precision can be effectively improved, the cost is low, and the difficulty of structural design can be reduced.

Description

Technical Field

[0001] The utility model relates to the field of switching converters, in particular to an over-temperature protection control circuit. Background Art

[0002] As the application environment of the power supply industry becomes increasingly harsh, especially for some air-cooled power supply equipment, the long-term operation of the fan inhales a large amount of dust, causing the power supply air duct to become blocked, resulting in the power supply power device overheating and failure. Over-temperature failure of power devices may cause grid tripping or even fire accidents. Therefore, the temperature of power devices must be monitored and the power supply equipment must be protected based on the monitoring results. If a temperature switch is used directly for monitoring, not only will the accuracy be poor and the cost be high, but the installation of the temperature switch will also be difficult. Utility Model Content

[0003] In view of this, an object of the present invention is to provide an over-temperature protection control circuit and a power supply device, which not only have high control accuracy and low cost, but also can reduce the difficulty of structural design.

[0004] In order to solve the above-mentioned purpose, the technical solution adopted by the present utility model is as follows:

[0005] In a first aspect, the present invention provides an over-temperature protection control circuit, the over-temperature protection control circuit comprising a reference circuit and a temperature detection circuit, wherein the output end of the reference circuit is connected to the input end of the temperature detection circuit;

[0006] The temperature detection circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first controllable precision voltage regulator, a first switching tube, a second switching tube, a first capacitor, and a thermistor. The reference electrode of the first controllable precision voltage regulator is connected to the output end of the reference circuit through the first resistor. The reference electrode of the first controllable precision voltage regulator is also connected to the first end of the first switching tube through the second resistor. The reference electrode of the first controllable precision voltage regulator is also connected to the second end of the first switching tube through the thermistor. The cathode of the first controllable precision voltage regulator is connected to the output end of the reference circuit through the third resistor. The cathode of the first controllable precision voltage regulator is also connected to the anode of the first controllable precision voltage regulator through the fourth resistor. The cathode of the first controllable precision voltage regulator is respectively connected to the control end of the first switching tube and the control end of the second switching tube. The first end of the second switching tube is connected to the ground signal through the first capacitor. The anode of the first controllable precision voltage regulator, the second end of the first switching tube, and the second end of the second switching tube are all connected to the ground signal. The first end of the second switching tube serves as the output end of the temperature detection circuit.

[0007] Optionally, the reference circuit includes a fifth resistor, a sixth resistor, a seventh resistor, a second capacitor and a second controllable precision voltage-stabilizing source, the first end of the fifth resistor is connected to the power supply signal, the second end of the fifth resistor is connected to the cathode of the second controllable precision voltage-stabilizing source, the cathode of the second controllable precision voltage-stabilizing source is connected to the anode of the second controllable precision voltage-stabilizing source through the second capacitor, the reference pole of the second controllable precision voltage-stabilizing source is connected to the cathode of the second controllable precision voltage-stabilizing source through the sixth resistor, the reference pole of the second controllable precision voltage-stabilizing source is also connected to the anode of the second controllable precision voltage-stabilizing source through the seventh resistor, the anode of the second controllable precision voltage-stabilizing source is connected to the ground signal, and the cathode of the second controllable precision voltage-stabilizing source is connected to the input end of the temperature detection circuit.

[0008] Optionally, the first switch tube is an NMOS tube, the first end of the first switch tube is a drain, the second end of the first switch tube is a source, and the control end of the first switch tube is a gate.

[0009] Optionally, the second switch tube is an NMOS tube, the first end of the second switch tube is a drain, the second end of the second switch tube is a source, and the control end of the second switch tube is a gate.

[0010] Optionally, the thermistor is an NTC thermistor.

[0011] In a second aspect, the present invention further provides a power supply device, comprising a power controller and an over-temperature protection control circuit as described in the first aspect, wherein the output end of the over-temperature protection control circuit is connected to the input end of the power controller.

[0012] The beneficial effects of the utility model are:

[0013] The utility model adopts a thermistor in the temperature detection circuit to replace the temperature switch in the traditional solution, which not only effectively improves the control accuracy with low cost, but also reduces the difficulty of structural design. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The utility model is a schematic diagram of an over-temperature protection control circuit. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0016] refer to Figure 1, an embodiment of the utility model provides an over-temperature protection control circuit, which specifically includes a reference circuit 200 and a temperature detection circuit 100, wherein the output end of the reference circuit 200 is connected to the input end of the temperature detection circuit 100;

[0017] The temperature detection circuit 100 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first controllable precision voltage regulator HR1, a first switch tube Q1, a second switch tube Q2, a first capacitor C1 and a thermistor RT1. The reference electrode of the first controllable precision voltage regulator HR1 is connected to the output end of the reference circuit 200 through the first resistor R1. The reference electrode of the first controllable precision voltage regulator HR1 is also connected to the first end of the first switch tube Q1 through the second resistor R2. The reference electrode of the first controllable precision voltage regulator HR1 is also connected to the second end of the first switch tube Q1 through the thermistor RT1. The first controllable precision voltage regulator HR1 The cathode of the first controllable precision voltage-stabilizing source HR1 is connected to the output end of the reference circuit 200 through the third resistor R3, the cathode of the first controllable precision voltage-stabilizing source HR1 is further connected to the anode of the first controllable precision voltage-stabilizing source HR1 through the fourth resistor R4, the cathode of the first controllable precision voltage-stabilizing source HR1 is respectively connected to the control end of the first switching tube Q1 and the control end of the second switching tube Q2, the first end of the second switching tube Q2 is connected to the ground signal through the first capacitor C1, the anode of the first controllable precision voltage-stabilizing source HR1, the second end of the first switching tube Q1 and the second end of the second switching tube Q2 are all connected to the ground signal, and the first end of the second switching tube Q2 serves as the output end of the temperature detection circuit 100.

[0018] In this embodiment, the output of the temperature detection circuit 100 is connected to the power controller U1. The second end of the second switch Q2 is connected to the LL / SS pin of the power controller U1. One end of the first capacitor C1 connected to the ground signal GND is connected to the GND pin of the power controller U1. The VCC pin of the power controller U1 is connected to the power supply signal VCC. The LL / SS pin is a soft-start pin.

[0019] It should be noted that the switch tube in the embodiment of the present application can be one or more of various types of switch tubes such as a metal oxide semiconductor field effect transistor (MOSFET), a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT), a gallium nitride field effect transistor (GaN), a silicon carbide (SiC) power tube, etc., and the embodiment of the present application will not list them one by one. Each switch tube can include a first end, a second end and a control end, wherein the control end is used to control the conduction or disconnection of the switch tube. When the switch tube is turned on, current can be transmitted between the first end and the second end of the switch tube. When the switch tube is turned off, current cannot be transmitted between the first end and the second end of the switch tube. Taking MOSFET as an example, the control end of the switch tube is the gate, the first end of the switch tube can be the source of the switch tube, and the second end can be the drain of the switch tube, or the first end can be the drain of the switch tube and the second end can be the source of the switch tube.

[0020] In this embodiment, the first switching transistor Q1 is an NMOS transistor, with a first terminal of the first switching transistor Q1 being a drain, a second terminal of the first switching transistor Q1 being a source, and a control terminal of the first switching transistor Q1 being a gate. The second switching transistor Q2 is an NMOS transistor, with a first terminal of the second switching transistor Q2 being a drain, a second terminal of the second switching transistor Q2 being a source, and a control terminal of the second switching transistor Q2 being a gate. The thermistor RT1 is an NTC thermistor RT1.

[0021] In this embodiment, the first controllable precision voltage regulator HR1 is implemented by a TL431 chip. According to circuit analysis, before the first switch Q1Q1 is turned on, the voltage at pin 1 of the first controllable precision voltage regulator HR1 is When the temperature of the power device is normal, the resistance of the thermistor RT1 is large and the voltage Vo1 is greater than 2.5V. Therefore, the 3rd pin of the first controllable precision voltage regulator HR1 is low, the gate of the second switch tube Q2 is low, the second switch tube Q2 is in the off state, and the constant current source inside the power controller U1 charges the first capacitor C1 to the reference voltage of the power controller U1 through the LL / SS pin. The power controller U1 works normally. In abnormal working conditions, the temperature of the power device rises and the resistance of the thermistor RT1 gradually decreases. When the voltage Vo1 is 1 is less than 2.5V, at this time, the 3rd pin of the first controllable precision voltage regulator HR1 is high, the gate of the second switch tube Q2 is high, the second switch tube Q2 is in the on state, the LL / SS pin of the power controller U1 will be pulled low to the ground signal GND, the power controller U1 stops working, at the same time as the 3rd pin of the first controllable precision voltage regulator HR1 is high, the gate of the first switch tube Q1 is high, the first switch tube Q1 is turned on, the second resistor R2 is connected in parallel with the thermistor RT1, playing a hysteresis role, at this time the 1st corner voltage of the first controllable precision voltage regulator HR1 After the power controller U1 stops working, the temperature of the power device of the power supply decreases, and the resistance of the thermistor RT1 gradually decreases. When the voltage Vo1 is less than 2.5V, the 3rd pin of the first controllable precision voltage regulator HR1 becomes low again, the gate of the second switch tube Q2 is low, and the second switch tube Q2 is in the off state. The constant current source inside the power controller U1 charges the first capacitor C1 to the reference voltage of the power controller U1 through the LL / SS pin, and the power controller U1 starts to work normally again.

[0022] In one embodiment, the reference circuit 200 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a second capacitor C2, and a second controllable precision voltage-stabilizing source HR2. The first end of the fifth resistor R5 is connected to the power supply signal, the second end of the fifth resistor R5 is connected to the cathode of the second controllable precision voltage-stabilizing source HR2, the cathode of the second controllable precision voltage-stabilizing source HR2 is connected to the anode of the second controllable precision voltage-stabilizing source HR2 through the second capacitor C2, the reference electrode of the second controllable precision voltage-stabilizing source HR2 is connected to the cathode of the second controllable precision voltage-stabilizing source HR2 through the sixth resistor R6, the reference electrode of the second controllable precision voltage-stabilizing source HR2 is also connected to the anode of the second controllable precision voltage-stabilizing source HR2 through the seventh resistor R7, the anode of the second controllable precision voltage-stabilizing source HR2 is connected to the ground signal, and the cathode of the second controllable precision voltage-stabilizing source HR2 is connected to the input end of the temperature detection circuit 100.

[0023] In this embodiment, the second controllable precision voltage regulator HR2 is implemented by a TL431 chip, and the reference circuit 200 is mainly used to provide a reference voltage for voltage comparison.

[0024] In addition, an embodiment of the present invention further provides a power supply device, including a power controller U1 and an over-temperature protection control circuit as described in the above embodiment, wherein the output of the over-temperature protection control circuit is connected to the input of the power controller U1. The specific circuit principles are consistent with those of the above embodiment and will not be further described here.

[0025] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An over-temperature protection control circuit, characterized in that: The over-temperature protection control circuit includes a reference circuit and a temperature detection circuit, wherein the output end of the reference circuit is connected to the input end of the temperature detection circuit; The temperature detection circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first controllable precision voltage regulator, a first switching tube, a second switching tube, a first capacitor, and a thermistor. The reference electrode of the first controllable precision voltage regulator is connected to the output end of the reference circuit through the first resistor. The reference electrode of the first controllable precision voltage regulator is also connected to the first end of the first switching tube through the second resistor. The reference electrode of the first controllable precision voltage regulator is also connected to the second end of the first switching tube through the thermistor. The cathode of the first controllable precision voltage regulator is connected to the output end of the reference circuit through the third resistor. The cathode of the first controllable precision voltage regulator is also connected to the anode of the first controllable precision voltage regulator through the fourth resistor. The cathode of the first controllable precision voltage regulator is respectively connected to the control end of the first switching tube and the control end of the second switching tube. The first end of the second switching tube is connected to the ground signal through the first capacitor. The anode of the first controllable precision voltage regulator, the second end of the first switching tube, and the second end of the second switching tube are all connected to the ground signal. The first end of the second switching tube serves as the output end of the temperature detection circuit.

2. The over-temperature protection control circuit according to claim 1, characterized in that: The reference circuit includes a fifth resistor, a sixth resistor, a seventh resistor, a second capacitor and a second controllable precision voltage-stabilizing source. The first end of the fifth resistor is connected to the power supply signal, the second end of the fifth resistor is connected to the cathode of the second controllable precision voltage-stabilizing source, the cathode of the second controllable precision voltage-stabilizing source is connected to the anode of the second controllable precision voltage-stabilizing source through the second capacitor, the reference electrode of the second controllable precision voltage-stabilizing source is connected to the cathode of the second controllable precision voltage-stabilizing source through the sixth resistor, the reference electrode of the second controllable precision voltage-stabilizing source is also connected to the anode of the second controllable precision voltage-stabilizing source through the seventh resistor, the anode of the second controllable precision voltage-stabilizing source is connected to the ground signal, and the cathode of the second controllable precision voltage-stabilizing source is connected to the input end of the temperature detection circuit.

3. The over-temperature protection control circuit according to claim 1, wherein: The first switch tube is an NMOS tube, the first end of the first switch tube is a drain, the second end of the first switch tube is a source, and the control end of the first switch tube is a gate.

4. The over-temperature protection control circuit according to claim 1, wherein: The second switch tube is an NMOS tube, the first end of the second switch tube is a drain, the second end of the second switch tube is a source, and the control end of the second switch tube is a gate.

5. The over-temperature protection control circuit according to claim 1, wherein: The thermistor is an NTC thermistor.

6. A power supply device, characterized in that: It comprises a power controller and an over-temperature protection control circuit according to any one of claims 1 to 5, wherein the output end of the over-temperature protection control circuit is connected to the input end of the power controller.

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