Overtemperature protection device, method and switching power supply

Abstract

The present disclosure proposes an over-temperature protection device, method and switching power supply, which relate to the field of electronic circuit technology. An over-temperature protection device disclosed in the present disclosure includes: a temperature-controlled voltage output circuit, which is configured to output a temperature-controlled voltage according to temperature changes, wherein the temperature-controlled voltage changes with the change of temperature when the temperature is greater than a predetermined protection value; a measurement comparison circuit, which is configured to compare the temperature-controlled voltage and the sampled voltage value on the controlled circuit; a drive circuit, which is configured to limit the current size on the controlled circuit so that the sampled voltage value is not greater than the temperature-controlled voltage. Such a temperature-controlled current-limiting device can adjust the temperature-controlled voltage according to the change of temperature when the temperature is higher than the predetermined protection value, and then determine the on and off of the controlled circuit according to the sampled voltage on the controlled circuit and the temperature-controlled voltage, thereby realizing the control of the current size according to the temperature and increasing the available time of the controlled device.

Description

Technical Field

[0001] The present disclosure relates to the technical field of electronic circuits, and in particular to an over-temperature protection device, method and switching power supply. Background Art

[0002] In switching power supply products, temperature is a very critical performance indicator. Excessive temperature will cause failure of temperature-sensitive semiconductor devices (such as MOS (Metal-Oxid-Semiconductor, metal oxide semiconductor) tubes, triodes), capacitors and other components. When the temperature exceeds a certain value, the failure rate increases exponentially. Statistics show that the reliability of electronic components will decrease by 10% for every 2°C increase in temperature; and the life span when the temperature rises by 50°C is only 1 / 6 of the life span when the temperature rises by 25°C. In addition to electrical stress, temperature is the most important factor affecting the reliability and stability of switching power supply components. Especially when the ambient temperature is high, coupled with the heat generated by the switching power supply itself, it is easy to make electronic components work at high temperatures and accelerate the aging of the power supply. Therefore, an over-temperature protection circuit must be used in the switching power supply circuit to control the operating temperature of the switching power supply components within the allowable range to ensure its reliability and stability. Summary of the invention

[0003] The inventors found that in the related art, the over-temperature protection circuits used in analog circuits all determine whether to trigger protection by collecting the ambient temperature or the temperature of the power module. When the ambient temperature or the temperature of the power module exceeds the protection value, the protection action is triggered, the pulse is blocked, and the power supply stops working to prevent the power supply from working in a high temperature environment. Such an over-temperature protection circuit only blocks the pulse through the logic AND gate when the temperature is higher than the protection value, so that the power supply stops working. The power supply has only two states: working and not working, which shortens the available time of the switching power supply and limits the scope of use of the switching power supply.

[0004] One object of the present disclosure is to increase the usable time of a controlled circuit.

[0005] According to one aspect of the present disclosure, an over-temperature protection device is proposed, including: a temperature-controlled voltage output circuit, configured to output a temperature-controlled voltage according to temperature changes, wherein the temperature-controlled voltage changes with changes in temperature when the temperature is greater than a predetermined protection value; a measurement comparison circuit, configured to compare the temperature-controlled voltage and a sampled voltage value on a controlled circuit; and a drive circuit, configured to limit the current size on the controlled circuit so that the sampled voltage value is not greater than the temperature-controlled voltage.

[0006] Optionally, the temperature-controlled voltage changes with temperature when the temperature is greater than a predetermined protection value, including: the temperature-controlled voltage remains unchanged when the temperature is less than or equal to the predetermined protection value, and decreases with increasing temperature after the temperature is greater than the predetermined protection value.

[0007] Optionally, the temperature-controlled voltage output circuit includes: an over-temperature judgment sub-circuit, configured to output an initial temperature-controlled voltage according to temperature changes, the initial temperature-controlled voltage remains unchanged when the temperature is less than or equal to a predetermined protection value, and increases with increasing temperature after the temperature is greater than the predetermined protection value; a subtraction sub-circuit, configured to output a temperature-controlled voltage according to the initial temperature-controlled voltage, wherein the temperature-controlled voltage decreases as the initial temperature-controlled voltage increases.

[0008] Optionally, the over-temperature judgment subcircuit includes: a first power supply circuit and a second power supply circuit; when the temperature is less than or equal to a predetermined protection value, a constant initial temperature control voltage is output through the first power supply circuit; when the temperature is greater than the predetermined protection value, the second power supply circuit is switched to output an initial temperature control voltage that increases with increasing temperature.

[0009] Optionally, the first power supply circuit includes a first reference voltage source and a first diode, the input end of the first diode is connected to the first reference voltage source, and the output end is connected to the output end of the over-temperature judgment sub-circuit; the second power supply circuit includes a second reference voltage source, a thermistor with a negative temperature coefficient and a grounding resistor, the first end of the thermistor is connected to the second reference voltage, and the second end is grounded through the grounding resistor; the input end of the second diode is connected to the second end of the thermistor, and the output end is connected to the output end of the over-temperature judgment sub-circuit; when the temperature is equal to a predetermined protection value, the voltage divided by the second reference voltage on the grounding resistor is equal to the voltage value of the first reference voltage.

[0010] Optionally, the measurement comparison circuit includes a comparator; the positive input terminal of the comparator is connected to the output terminal of the sampling voltage on the controlled circuit, the reverse input terminal is connected to the output terminal of the temperature control voltage output circuit, and the output terminal is the output terminal of the measurement comparison circuit.

[0011] Optionally, the driving circuit includes a latch and a transistor; the signal input terminal of the latch is connected to the output terminal of the measurement and comparison circuit, and the output terminal is connected to the gate of the transistor; the transistor is configured to control the on and off of the controlled circuit through the signal of the gate.

[0012] Optionally, when a low level is input to the signal input terminal of the latch and a high level is input to the clock signal input terminal, the output signal of the signal output terminal of the latch causes the transistor to control the controlled circuit to be turned on; when a high level is input to the signal input terminal of the latch and a low level is input to the clock signal input terminal, the output signal of the signal output terminal of the latch causes the transistor to control the controlled circuit to be turned off; when a low level is input to the signal input terminal of the latch and a low level is input to the clock signal input terminal, the output voltage of the signal output terminal of the latch remains unchanged.

[0013] Optionally, the transistor is an NMOS (N-Metal-Oxide-Semiconductor) tube; when a low level is input to the signal input end of the latch and a high level is input to the clock signal input end, the signal output end of the latch outputs a high level to the gate of the NMOS tube; when a high level is input to the signal input end of the latch and a low level is input to the clock signal input end, the signal output end of the latch outputs a low level to the gate of the NMOS tube.

[0014] Optionally, the transistor is a PMOS (Positive Channel Metal Oxide Semiconductor) tube; when a low level is input to the signal input end of the latch and a high level is input to the clock signal input end, the signal output end of the latch outputs a low level to the gate of the PMOS tube; when a high level is input to the signal input end of the latch and a low level is input to the clock signal input end, the signal output end of the latch outputs a high level to the gate of the PMOS tube.

[0015] Such an over-temperature protection device can adjust the temperature control voltage according to the temperature change when the temperature is higher than the preset protection value, and then determine the on and off of the controlled circuit according to the sampling voltage and the temperature control voltage on the controlled circuit, thereby controlling the current size according to the temperature, increasing the available time of the controlled circuit, and expanding the use range of the controlled equipment.

[0016] According to another aspect of the present disclosure, a switching power supply is provided, comprising: a switching power supply main circuit; and any one of the over-temperature protection devices mentioned above, configured to perform over-temperature protection on the switching power supply main circuit.

[0017] Such a switching power supply can adjust the temperature control voltage according to the temperature change when the temperature is higher than the preset protection value, and then determine the on and off of the main circuit of the switching power supply according to the sampling voltage and the temperature control voltage on the main circuit of the switching power supply, thereby controlling the current size according to the temperature, increasing the available time of the switching power supply, and expanding the scope of use of the switching power supply.

[0018] According to another aspect of the present disclosure, an over-temperature protection method is proposed, including: outputting a temperature-controlled voltage according to temperature changes, wherein the temperature-controlled voltage changes with temperature changes when the temperature is greater than a predetermined protection value; comparing the temperature-controlled voltage with a sampled voltage value on a controlled circuit; and limiting the current on the controlled circuit so that the sampled voltage value is not greater than the temperature-controlled voltage.

[0019] Optionally, the temperature-controlled voltage remains unchanged when the temperature is less than or equal to a predetermined protection value, and decreases as the temperature increases after the temperature is greater than the predetermined protection value.

[0020] Optionally, outputting a temperature-controlled voltage according to temperature changes includes: outputting an initial temperature-controlled voltage according to temperature changes, the initial temperature-controlled voltage remains unchanged when the temperature is less than or equal to a predetermined protection value, and increases with increasing temperature after the temperature is greater than the predetermined protection value; outputting a temperature-controlled voltage according to the initial temperature-controlled voltage, wherein the temperature-controlled voltage decreases as the initial temperature-controlled voltage increases.

[0021] Optionally, outputting an initial temperature control voltage according to temperature changes includes: when the temperature is less than or equal to a predetermined protection value, outputting a constant initial temperature control voltage through the first power supply circuit; when the temperature is greater than the predetermined protection value, switching to the second power supply circuit to output an initial temperature control voltage that increases with increasing temperature.

[0022] Optionally, comparing the temperature control voltage and the sampled voltage value on the controlled circuit includes: when the sampled voltage is greater than the temperature control voltage, outputting a high level; when the sampled voltage is less than the temperature control voltage, outputting a low level.

[0023] Optionally, limiting the current in the controlled circuit by controlling the sampling voltage value to be no greater than the temperature control voltage includes: controlling the output level of the latch by connecting the output of the comparator to the signal input of the latch; controlling the on-off between the source and drain of the transistor through the signal output of the latch connected to the gate of the transistor, wherein the transistor controls the on-off of the controlled circuit.

[0024] Optionally, when a low level is input to the signal input terminal of the latch and a high level is input to the clock signal input terminal, the output signal of the signal output terminal of the latch causes the transistor to control the controlled circuit to be turned on; when a high level is input to the signal input terminal of the latch and a low level is input to the clock signal input terminal, the output signal of the signal output terminal of the latch causes the transistor to control the controlled circuit to be turned off; when a low level is input to the signal input terminal of the latch and a low level is input to the clock signal input terminal, the output voltage of the signal output terminal of the latch remains unchanged.

[0025] Through this method, the temperature control voltage can be adjusted according to the temperature change when the temperature is higher than the preset protection value, and then the on and off of the controlled circuit can be determined according to the sampled voltage and the temperature control voltage on the controlled circuit, thereby achieving the control of the current size according to the temperature, increasing the available time of the controlled circuit, and expanding the use range of the controlled equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide a further understanding of the present disclosure and constitute a part of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure. In the drawings:

[0027] Figure 1 It is a schematic diagram of an embodiment of an over-temperature protection device disclosed in the present invention.

[0028] Figure 2 The diagram is a schematic diagram of an embodiment of a temperature-controlled voltage output circuit in the over-temperature protection device disclosed in the present invention.

[0029] Figure 3 This is a circuit diagram of another embodiment of a temperature-controlled voltage output circuit in the over-temperature protection device disclosed in the present invention.

[0030] Figure 4 The diagram is a schematic diagram of an embodiment of a measurement comparison circuit and a drive circuit in the over-temperature protection device of the present disclosure.

[0031] Figure 5 A circuit diagram of another embodiment of the over-temperature protection device disclosed in the present invention.

[0032] Figure 6 This is a diagram showing the effect of using an embodiment of the over-temperature protection device disclosed herein.

[0033] Figure 7 A schematic diagram of an embodiment of a switching power supply disclosed herein.

[0034] Figure 8 The present invention is a flow chart of an embodiment of an over-temperature protection method. DETAILED DESCRIPTION

[0035] The technical solution of the present disclosure is further described in detail below through the accompanying drawings and embodiments.

[0036] A schematic diagram of an embodiment of the over-temperature protection device disclosed in the present invention is shown in FIG. Figure 1 shown.

[0037] The temperature-controlled voltage output circuit 11 can output a temperature-controlled voltage to the measurement comparison circuit. The temperature-controlled voltage changes with the temperature of the current controlled circuit. In one embodiment, the temperature-controlled voltage remains unchanged when the temperature is less than or equal to a predetermined protection value, and decreases as the temperature increases after the temperature is greater than the predetermined protection value. In one embodiment, the temperature-controlled voltage can be adjusted by a circuit including a thermistor.

[0038] The measurement comparison circuit can compare the temperature control voltage with the sampled voltage value on the controlled circuit. The sampled voltage value can be the voltage drop across the sampling resistor on the controlled circuit, which can reflect the current situation on the controlled circuit. The sampled voltage value is not limited to being obtained by resistor sampling, but can also be obtained by current sensor sampling or other sampling methods.

[0039] The driving circuit can limit the current size on the controlled circuit so that the sampling voltage value is not greater than the temperature control voltage. In one embodiment, since the temperature control voltage decreases with increasing temperature, the maximum value of the sampling voltage decreases, thereby reducing the maximum value of the current on the controlled circuit.

[0040] Such an over-temperature protection device can adjust the temperature control voltage according to the temperature change when the temperature is higher than the preset protection value, and then determine the on and off of the controlled circuit according to the sampling voltage and the temperature control voltage on the controlled circuit, thereby controlling the current size according to the temperature, increasing the available time of the controlled circuit, and expanding the use range of the controlled equipment.

[0041] In one embodiment, the controlled circuit may be a switching power supply circuit in various forms, thereby increasing the usable time of the switching power supply and expanding the use range of the switching power supply.

[0042] A schematic diagram of an embodiment of a temperature-controlled voltage output circuit in an over-temperature protection device disclosed in the present invention is shown in FIG. Figure 2 The temperature control voltage output circuit may include an over-temperature judgment subcircuit 211 and a subtraction subcircuit 212 .

[0043] The over-temperature judgment subcircuit 211 can output an initial temperature control voltage according to the temperature change. The initial temperature control voltage remains unchanged when the temperature is less than or equal to the predetermined protection value, and increases with the temperature increase after the temperature is greater than the predetermined protection value. Figure 2 As shown, the over-temperature judgment subcircuit 211 includes a first power supply circuit 2111 and a second power supply circuit 2112. The first power supply circuit 2111 can output a constant voltage, and the second power supply circuit 2112 includes a thermistor and can output a voltage that increases with increasing temperature. When the temperature is less than or equal to a predetermined protection value, the first power supply circuit 2111 outputs a voltage; when the temperature is greater than the predetermined protection value, the second power supply circuit 2112 outputs a voltage.

[0044] The subtraction subcircuit 212 can output a temperature control voltage according to the initial temperature control voltage, and the temperature control voltage decreases as the initial temperature control voltage increases.

[0045] Such an over-temperature protection device can utilize the over-temperature judgment sub-circuit and the subtraction sub-circuit to realize the output temperature control voltage, has a reliable structure and is easy to realize, which is conducive to popularization and application.

[0046] A circuit diagram of another embodiment of the temperature-controlled voltage output circuit in the over-temperature protection device disclosed in the present invention is shown in FIG. Figure 3 shown.

[0047] The first power supply circuit 3111 includes a first reference voltage source Vr1 and a first diode D1, the input end of the first diode D1 is connected to the first reference voltage source Vr1, and the output end is connected to the output end of the over-temperature judgment sub-circuit. The initial temperature control voltage is represented by Ve.

[0048] The second power supply circuit 3112 includes a second reference voltage source Vr2, a thermistor R1 with a negative temperature coefficient and a grounding resistor R2, wherein the first end of the thermistor R1 is connected to the second reference voltage Vr2, and the second end is grounded through the grounding resistor R2; the input end of the second diode D2 is connected to the second end of the thermistor R1, and the output end is connected to the output end of the over-temperature judgment sub-circuit.

[0049] When the temperature is lower than a predetermined protection value, the divided voltage Vr2*R2 / (R1+R2) of the second reference voltage Vr2 on the grounding resistor is lower than Vr1, Ve=Vr1.

[0050] When the temperature is equal to the predetermined protection value, the divided voltage of the second reference voltage on the grounding resistor is Vr2*R2 / (R1+R2)=Vr1=Ve.

[0051] When the temperature is greater than a predetermined protection value, the divided voltage Vr2*R2 / (R1+R2) of the second reference voltage Vr2 on the grounding resistor is greater than Vr1, and the first power supply circuit 3111 is cut off, Ve=Vr2*R2 / (R1+R2).

[0052] Such an over-temperature judgment sub-circuit can use the first power supply circuit 3111 to provide an initial temperature control voltage when the temperature is lower than a predetermined protection value, thereby ensuring the stability of the initial temperature control voltage; when the temperature is higher than the predetermined protection value, the second power supply circuit 3112 is used to provide an initial temperature control voltage, so that the initial temperature control voltage increases with increasing temperature. The circuit is reliable and small in size, which is conducive to integrated applications.

[0053] In one embodiment, Figure 3 As shown, the subtraction subcircuit 312 can be implemented by an operational amplifier. For the convenience of operation, R3=R4=R5=R6 can be set, and the temperature-controlled voltage Ve' output by the operational amplifier U1 is proportional to Vr3-Ve, so that Ve' decreases with the increase of Ve, that is, it decreases with the increase of temperature. The circuit is reliable and small in size, which is conducive to integrated applications. In one embodiment, the subtraction subcircuit 312 can realize the function of Ve' decreasing with the increase of Ve through any subtraction circuit.

[0054] A schematic diagram of an embodiment of a measuring comparison circuit and a driving circuit in the over-temperature protection device disclosed in the present invention is shown in FIG. Figure 4 shown.

[0055] The measurement comparison circuit includes a comparator 42, and the driving circuit can be a PWM (Pulse Width Modulation) driving circuit, including a latch 431 and a transistor 433. The two input ends of the comparator 42 are respectively connected to the output end of the sampling voltage on the controlled circuit and the output end of the temperature-controlled voltage output circuit, and the output end is connected to the input end of the driving circuit. The comparator 42 outputs a signal to the signal input end of the latch 431. The signal output end of the latch is connected to the gate of the transistor 432. The source and drain of the transistor 432 are connected in series to the controlled circuit, and the output signal of the signal output end of the latch controls the on-off between the source and drain of the transistor, thereby controlling the on-off of the controlled circuit.

[0056] Such an over-temperature protection device can use the output signal of the latch to control the on and off of the controlled circuit, and the output signal of the latch is related to the current and temperature of the controlled circuit, thereby limiting the current according to the temperature. While preventing the device from overheating, it can also enable the device to be used normally by reducing the current, thereby improving the temperature tolerance of the controlled circuit and expanding the scope of use of the controlled device.

[0057] A circuit diagram of another embodiment of the over-temperature protection device disclosed in the present invention is shown in FIG. Figure 5 As shown. The positive input terminal of the comparator U2 is connected to the output terminal of the sampling voltage on the controlled circuit, and the reverse input terminal is connected to the output terminal of the temperature-controlled voltage output circuit. The input terminal R of the latch is connected to the output terminal of the comparator U2, the S terminal is connected to the clock signal, and the output terminal Q is connected to the gate of the transistor Q1. Vd is the voltage source identifier of the controlled circuit, and the source and drain of the transistor Q1 are located in the controlled circuit. Rs is the sampling resistor on the controlled circuit, and Vs is the voltage drop across Rs, which is the sampling voltage.

[0058] In one embodiment, Q1 is an NMOS transistor, and the state change of the latch can be shown in Table 1:

[0059] Table 1 Output logic of latch when transistor is NMOS tube

[0060]

[0061] In another embodiment, if Q1 is a PMOS transistor, when S is 1 and R is 0, Q is 0; when S is 0 and R is 1, Q is 1.

[0062] The effect diagram of an embodiment of the use effect of the over-temperature protection device is as follows Figure 6 As shown. Taking Q1 as an NMOS transistor as an example, if the source and drain of the transistor are turned on, the gate needs to input a high level, that is, R needs to input 0, that is, Ve'>Vs, so that the current Is in the switch circuit can be guaranteed to be less than Ve' / Rs. When the temperature is lower than the predetermined protection value, Ve' is higher (such as Figure 6 When the temperature exceeds the predetermined protection value, Ve' decreases as the temperature rises, the maximum value of Vs decreases, and the maximum value of Vs / Rs also decreases, thereby achieving the control of the power supply current according to the temperature, and the power supply current decreases as the temperature increases, while ensuring that the operating temperature is within the allowable range, the normal use time of the equipment is increased.

[0063] A schematic diagram of an embodiment of the switching power supply disclosed in the present invention is shown in FIG. Figure 7 As shown. The switching power supply 70 includes a switching power supply main circuit 71 and an over-temperature protection device 72. The switching power supply main circuit refers to a circuit in the switching power supply that performs the function of controlling the on-off of the switch tube. The over-temperature protection device 72 can be any of the over-temperature protection devices mentioned above. The over-temperature protection device 72 can limit the sampling voltage of the switching power supply main circuit to not be greater than the temperature control voltage of the over-temperature protection device 72, and when the temperature is lower than the predetermined protection value, the temperature control voltage remains unchanged, and when the temperature is higher than the predetermined protection value, the temperature control voltage decreases as the temperature increases, so that the maximum value of the current of the switching power supply main circuit 71 decreases as the temperature increases.

[0064] Such a switching power supply can adjust the temperature control voltage according to the temperature change when the temperature is higher than the preset protection value, and then determine the on and off of the main circuit of the switching power supply according to the sampling voltage and the temperature control voltage on the main circuit of the switching power supply, thereby controlling the current size according to the temperature, increasing the available time of the switching power supply, and expanding the scope of use of the switching power supply.

[0065] A flow chart of an embodiment of the over-temperature protection method disclosed in the present invention is as follows: Figure 8 shown.

[0066] In step 801, a temperature-controlled voltage is output according to temperature changes, wherein the temperature-controlled voltage remains unchanged when the temperature is less than or equal to a predetermined protection value, and decreases as the temperature increases after the temperature is greater than the predetermined protection value.

[0067] In step 802, the temperature-controlled voltage is compared with a sampled voltage value on the controlled circuit.

[0068] In step 803, the current in the controlled circuit is limited so that the sampled voltage value is not greater than the temperature control voltage.

[0069] Through this method, the temperature control voltage can be adjusted according to the temperature change when the temperature is higher than the preset protection value, and then the on and off of the controlled circuit can be determined according to the sampled voltage and the temperature control voltage on the controlled circuit, thereby achieving the control of the current size according to the temperature, increasing the available time of the controlled circuit, and expanding the use range of the controlled equipment.

[0070] In one embodiment, the following can be used: Figure 2The structure shown in the figure first outputs an initial temperature control voltage according to the temperature change. The initial temperature control voltage remains unchanged when the temperature is less than or equal to the predetermined protection value, and increases with the temperature increase after the temperature is greater than the predetermined protection value. Then, a temperature control voltage is output according to the initial temperature control voltage, which decreases with the increase of the initial temperature control voltage. In one embodiment, the following can be used: Figure 3 The circuit structure shown outputs a temperature-controlled voltage. In one embodiment, the first power supply circuit and the second power supply circuit can be set to output an initial temperature-controlled voltage. When the temperature is less than or equal to a predetermined protection value, a constant initial temperature-controlled voltage is output through the first power supply circuit; when the temperature is greater than the predetermined protection value, the second power supply circuit is switched to output an initial temperature-controlled voltage that increases with increasing temperature. By using such a method, it is possible to keep the output voltage constant when the temperature is lower than the predetermined protection value, and to increase the output voltage with increasing temperature when the temperature is greater than the predetermined protection value, thereby realizing a two-stage conversion of the output voltage.

[0071] In one embodiment, the temperature control voltage and the sampled voltage value on the controlled circuit can be compared by a comparator, and a high level can be output when the sampled voltage is greater than the temperature control voltage; a low level can be output when the sampled voltage is less than the temperature control voltage, or vice versa. The output end of the comparator is connected to the signal input end of the latch to control the output end level of the latch, and the on-off between the source and drain of the transistor is controlled by the signal output end of the latch connected to the gate of the transistor, thereby controlling the on-off of the controlled circuit.

[0072] Through this method, the output signal of the latch can be used to control the on and off of the controlled circuit, and the output signal of the latch is related to the current and temperature of the controlled circuit, thereby limiting the current according to the temperature. While avoiding overheating of the device, it can also enable the device to be used normally by reducing the current, thereby improving the temperature tolerance of the controlled circuit and expanding the scope of use of the controlled device.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present disclosure rather than to limit it. Although the present disclosure has been described in detail with reference to the preferred embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present disclosure can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present disclosure, which should be included in the scope of the technical solution for protection of the present disclosure.

Claims

1. An over-temperature protection device, comprising: A temperature-controlled voltage output circuit is configured to output a temperature-controlled voltage according to temperature changes, wherein the temperature-controlled voltage changes with temperature changes when the temperature is greater than a predetermined protection value; A measurement comparison circuit is configured to compare the temperature-controlled voltage with a sampled voltage value on a controlled circuit; The driving circuit includes a latch and a transistor, and is configured to limit the current size of the controlled circuit so that the sampling voltage value is not greater than the temperature control voltage, wherein the signal input end of the latch is connected to the output end of the measurement comparison circuit, and the output end is connected to the gate of the transistor, and the transistor is configured to control the on and off of the controlled circuit through the signal of the gate, Wherein, the temperature-controlled voltage output circuit includes: a first power supply circuit and a second power supply circuit; The first power supply circuit includes a first reference voltage source and a first diode, the input end of the first diode is connected to the first reference voltage source, and the output end of the first diode is connected to the output end of the over-temperature judgment sub-circuit; The second power supply circuit includes a second reference voltage source, a thermistor with a negative temperature coefficient, a grounding resistor and a second diode, wherein a first end of the thermistor is connected to a second reference voltage, and a second end is grounded through the grounding resistor; an input end of the second diode is connected to the second end of the thermistor, and an output end of the second diode is connected to the output end of the over-temperature judgment sub-circuit.

2. The device according to claim 1, wherein: The temperature-controlled voltage changes with the temperature when the temperature is greater than the predetermined protection value, including: The temperature control voltage remains unchanged when the temperature is less than or equal to the predetermined protection value; The temperature control voltage decreases as the temperature increases after the temperature is greater than the predetermined protection value.

3. The device according to claim 2, wherein: The temperature-controlled voltage output circuit comprises: an over-temperature judgment subcircuit, comprising the first power supply circuit and the second power supply circuit, configured to output an initial temperature control voltage according to temperature changes, wherein the initial temperature control voltage remains unchanged when the temperature is less than or equal to a predetermined protection value, and increases with the increase of temperature after the temperature is greater than the predetermined protection value; The subtraction subcircuit is configured to output the temperature-controlled voltage according to the initial temperature-controlled voltage, wherein the temperature-controlled voltage decreases as the initial temperature-controlled voltage increases.

4. The device according to claim 3, wherein: When the temperature is less than or equal to the predetermined protection value, a constant initial temperature control voltage is output through the first power supply circuit; When the temperature is greater than the predetermined protection value, the second power supply circuit is switched to output an initial temperature-controlled voltage that increases with the increase of temperature.

5. The device according to claim 4, wherein: When the temperature is equal to the predetermined protection value, the divided voltage of the second reference voltage on the grounding resistor is equal to the voltage value of the first reference voltage.

6. The device according to any one of claims 1 to 5, wherein: The measurement comparison circuit includes a comparator; The positive input terminal of the comparator is connected to the output terminal of the sampling voltage on the controlled circuit, the reverse input terminal is connected to the output terminal of the temperature-controlled voltage output circuit, and the output terminal is the output terminal of the measurement comparison circuit.

7. The device according to any one of claims 1 to 5, wherein: When a low level is input to the signal input terminal of the latch and a high level is input to the clock signal input terminal, an output signal of the signal output terminal of the latch causes the transistor to control the controlled circuit to be turned on; When a high level is input to the signal input terminal of the latch and a low level is input to the clock signal input terminal, an output signal of the signal output terminal of the latch causes the transistor to control the controlled circuit to be disconnected; When a low level is input to the signal input terminal of the latch and a low level is input to the clock signal input terminal, the output voltage of the signal output terminal of the latch remains unchanged.

8. The device according to claim 7, wherein: The transistor is an N-type metal-oxide-semiconductor (NMOS) tube; when a low level is input to the signal input end of the latch and a high level is input to the clock signal input end, the signal output end of the latch outputs a high level to the gate of the NMOS tube; when a high level is input to the signal input end of the latch and a low level is input to the clock signal input end, the signal output end of the latch outputs a low level to the gate of the NMOS tube; or, The transistor is a P-type metal-oxide-semiconductor (PMOS) tube; when a low level is input to the signal input end of the latch and a high level is input to the clock signal input end, the signal output end of the latch outputs a low level to the gate of the PMOS tube; when a high level is input to the signal input end of the latch and a low level is input to the clock signal input end, the signal output end of the latch outputs a high level to the gate of the PMOS tube.

9. A switching power supply comprising: Switching power supply main circuit; and, The over-temperature protection device according to any one of claims 1 to 8 is configured to perform over-temperature protection on the main circuit of the switching power supply.

10. An over-temperature protection method, comprising: Outputting a temperature-controlled voltage according to temperature changes using a temperature-controlled voltage output circuit, wherein the temperature-controlled voltage changes with temperature changes when the temperature is greater than a predetermined protection value; Comparing the temperature-controlled voltage with a sampled voltage value on a controlled circuit; Limiting the current on the controlled circuit so that the sampled voltage value is not greater than the temperature-controlled voltage includes: controlling the output level of the latch by connecting the output of the comparator to the signal input of the latch; controlling the on-off between the source and drain of the transistor through the signal output of the latch connected to the gate of the transistor, wherein the transistor controls the on-off of the controlled circuit, Wherein, the temperature-controlled voltage output circuit includes: a first power supply circuit and a second power supply circuit; The first power supply circuit includes a first reference voltage source and a first diode, the input end of the first diode is connected to the first reference voltage source, and the output end of the first diode is connected to the output end of the over-temperature judgment sub-circuit; The second power supply circuit includes a second reference voltage source, a thermistor with a negative temperature coefficient, a grounding resistor and a second diode, wherein a first end of the thermistor is connected to a second reference voltage, and a second end is grounded through the grounding resistor; an input end of the second diode is connected to the second end of the thermistor, and an output end of the second diode is connected to the output end of the over-temperature judgment sub-circuit.

11. The method according to claim 10, wherein: The temperature control voltage remains unchanged when the temperature is less than or equal to the predetermined protection value, and decreases as the temperature increases after the temperature is greater than the predetermined protection value.

12. The method according to claim 11, wherein: Outputting a temperature-controlled voltage according to temperature changes includes: Outputting an initial temperature control voltage according to the temperature change, wherein the initial temperature control voltage remains unchanged when the temperature is less than or equal to a predetermined protection value, and increases as the temperature increases after the temperature is greater than the predetermined protection value; The temperature-controlled voltage is output according to the initial temperature-controlled voltage, wherein the temperature-controlled voltage decreases as the initial temperature-controlled voltage increases.

13. The method according to claim 12, wherein: Outputting the initial temperature control voltage according to the temperature change includes: When the temperature is less than or equal to the predetermined protection value, a constant initial temperature control voltage is output through the first power supply circuit; When the temperature is greater than the predetermined protection value, the second power supply circuit is switched to output an initial temperature-controlled voltage that increases with the increase of temperature.

14. The method according to claim 10 or 11, wherein: The comparing the temperature-controlled voltage with the sampled voltage value of the controlled circuit comprises: When the sampling voltage is greater than the temperature control voltage, a high level is output; When the sampling voltage is less than the temperature control voltage, a low level is output.

15. The method according to claim 10, wherein: When a low level is input to the signal input terminal of the latch and a high level is input to the clock signal input terminal, an output signal of the signal output terminal of the latch causes the transistor to control the controlled circuit to be turned on; When a high level is input to the signal input terminal of the latch and a low level is input to the clock signal input terminal, an output signal of the signal output terminal of the latch causes the transistor to control the controlled circuit to be disconnected; When a low level is input to the signal input terminal of the latch and a low level is input to the clock signal input terminal, the output voltage of the signal output terminal of the latch remains unchanged.

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