Switching power supply temperature control circuit

Abstract

The utility model relates to a switching power supply temperature control circuit which is directly connected to a secondary output end of a power supply and comprises an external power supply voltage and an output current sampling voltage, and the external power supply voltage is respectively connected with a reference circuit, a negative feedback circuit and an operational amplifier; the reference circuit is connected with a normal phase input end of the operational amplifier; the negative feedback circuit is connected with the negative phase input end and the negative phase output end of the operational amplifier; the output current sampling voltage is connected with the negative phase input end of the operational amplifier through the negative feedback circuit; and the operational amplifier is grounded. The problems that the service life is shortened and the cost of replacing the power supply is increased due to the fact that the power supply is quickly aged under long-time high-temperature work are solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to a switching power supply temperature control circuit. BACKGROUND

[0002] In the field of LED lamp lighting, generally, the temperature is higher in low-latitude area, and the outdoor lighting lamp is in a high-temperature working environment, if there is not enough understanding of the local environment, it may cause the lamp to be damaged due to working in a high-temperature environment, which puts forward more strict requirements for the high-temperature work of the outdoor lighting lamp.

[0003] Therefore, a switching power supply temperature control circuit is provided. SUMMARY

[0004] The utility model discloses a switching power supply temperature control circuit that overcomes the defects of the prior art, solves the problem of rapid aging of the power supply under long-time high-temperature work, shortens the service life, and increases the cost of replacing the power supply.

[0005] The technical scheme for achieving the above-mentioned purpose is as follows:

[0006] A switching power supply temperature control circuit is directly connected to the secondary output end of the power supply, comprising: an external power supply voltage and an output current sampling voltage,

[0007] The external power supply voltage is connected to a reference circuit, a negative feedback circuit and an operational amplifier, respectively;

[0008] The reference circuit is connected to the positive input end of the operational amplifier;

[0009] The negative feedback circuit is connected to the negative input end and the output end of the operational amplifier;

[0010] The output current sampling voltage is connected to the negative input end of the operational amplifier through the negative feedback circuit;

[0011] The operational amplifier is grounded.

[0012] Preferably, the reference circuit comprises a second resistor and a seventh resistor,

[0013] The external power supply voltage is connected to the second resistor, the seventh resistor and the output end of the operational amplifier, respectively;

[0014] The other end of the second resistor is connected to a thermistor and the drain of a MOS tube, respectively;

[0015] The other end of the seventh resistor and the gate of the MOS tube are grounded through a temperature switch;

[0016] The other end of the thermistor and the source of the MOS tube are connected to a first resistor and the cathode of a zener diode, respectively;

[0017] The other end of the first resistance is connected with the fourth resistance and the positive input end of the operational amplifier respectively;

[0018] The other end of the fourth resistance is grounded and the anode of the stabilizing diode is grounded;

[0019] The first capacitor is connected in parallel with the fourth resistance.

[0020] Preferably, the negative feedback circuit comprises: the eighth resistance,

[0021] The external power supply voltage is connected with the input end of the optical coupler through the eighth resistance;

[0022] The output end of the optical coupler is connected with the anode of the diode;

[0023] The cathode of the diode is connected with the fifth resistance;

[0024] The other end of the fifth resistance is connected with the output end of the operational amplifier and the sixth resistance respectively;

[0025] The other end of the sixth resistance is connected with the second capacitor;

[0026] The other end of the second capacitor is connected with the third resistance and the negative input end of the operational amplifier respectively;

[0027] The third capacitor is connected in parallel with the sixth resistance and the second capacitor;

[0028] The output current sampling voltage is connected with the negative input end of the operational amplifier through the third resistance.

[0029] Preferably, the reference circuit is used for providing the reference voltage Vref and comparing with the output current sampling voltage through the operational amplifier.

[0030] The utility model discloses the beneficial effect is: the utility model through being below the rated temperature of temperature control switch, the operational amplifier is sampled to the power output end current through the third resistance, to realize the control to output current, when temperature reaches temperature control switch temperature, MOS pipe is closed, thermistor is accessed, reduces output current, realizes the purpose of temperature reduction, can ensure that the power supply working process will not produce excessively high temperature and prolongs power supply service life to some extent. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is the schematic diagram of the utility model one kind open switch power supply temperature control circuit. DETAILED DESCRIPTION

[0032] The technical solutions of the utility model will be described clearly and completely in connection with the drawings. In the description of the utility model, it should be explained that the directions or position relations of the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like are based on the directions or position relations shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and therefore cannot be understood as limiting the utility model. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying the importance of the opposite.

[0033] The utility model will be further described in connection with the drawings.

[0034] As Figure 1 shown, a switching power supply temperature control circuit is directly connected to the secondary output end of the power supply, and is characterized in that it comprises: an external power supply voltage VCC and an output current sampling voltage Vcs, the external power supply voltage VCC is connected to a reference circuit, a negative feedback circuit and an operational amplifier U1 respectively; the reference circuit is connected to the positive input end of the operational amplifier U1; the negative feedback circuit is connected to the negative input end and the output end of the operational amplifier U1; the output current sampling voltage Vcs is connected to the negative input end of the operational amplifier U1 through the negative feedback circuit; and the operational amplifier U1 is grounded.

[0035] In the embodiment, the reference circuit comprises: a second resistor R2 and a seventh resistor R7, the external power supply voltage VCC is connected to the second resistor R2, the seventh resistor R7 and the output end of the operational amplifier U1 respectively; the other end of the second resistor R2 is connected to the drain of a MOS tube Q1 and a thermistor PTC respectively; the other end of the seventh resistor R7 and the gate of the MOS tube Q1 are grounded through a temperature switch S1; the other end of the thermistor PTC and the source of the MOS tube Q1 are connected to a first resistor R1 and the cathode of a zener diode ZD1 respectively; the other end of the first resistor R1 is connected to a fourth resistor R4 and the positive input end of the operational amplifier U1 respectively; the other end of the fourth resistor R4 and the anode of the zener diode ZD1 are grounded; and the fourth resistor R4 is connected in parallel with a first capacitor C1 across the fourth resistor R4.

[0036] In the embodiment, the negative feedback circuit comprises: an eighth resistor R8, an input end of an optocoupler OP1 is connected to the eighth resistor R8 through a power supply voltage VCC; an output end of the optocoupler OP1 is connected to an anode of a diode D1; a cathode of the diode D1 is connected to a fifth resistor R5; the fifth resistor R5 is connected to an output end of an operational amplifier U1 and a sixth resistor R6 respectively; the sixth resistor R6 is connected to a second capacitor C2; the second capacitor C2 is connected to a third resistor R3 and a negative phase input end of the operational amplifier U1 respectively; the sixth resistor R6 and the second capacitor C2 are connected to a third capacitor C3 in parallel; an output current sampling voltage Vcs is connected to the negative phase input end of the operational amplifier U1 through the third resistor R3.

[0037] In the embodiment, the reference circuit is used to provide a reference voltage Vref, and compare the reference voltage Vref with the output current sampling voltage Vcs through the operational amplifier.

[0038] Working principle:

[0039] After the power supply is powered on, when the temperature of the power supply is below the rated temperature of the temperature switch S1, the temperature switch S1 is always open, at this time, the MOS tube Q1 is turned on, the reference circuit divides the voltage to provide the reference voltage Vref for the operational amplifier U1, the output current sampling voltage Vcs is compared with the reference voltage Vref through the third resistor R3, and the signal is transmitted to the primary side through the negative feedback circuit to realize full load output.

[0040] When the temperature of the power supply reaches the rated temperature of the temperature switch S1 but does not reach the target temperature designed by the thermistor PTC, the temperature switch S1 is closed, at this time, the MOS tube Q1 is turned off, the thermistor PTC is connected, the reference circuit divides the voltage to provide the reference voltage Vref for the operational amplifier U1, the output current sampling voltage Vcs is compared with the reference voltage Vref through the third resistor R3, at this time, the power supply is still full load output.

[0041] When the temperature of the power supply reaches the target temperature designed by the thermistor PTC, the zener diode ZD1 does not participate in the work, at this time, the reference circuit divides the voltage to provide the reference voltage Vref for the operational amplifier U1, and the reference voltage Vref gradually decreases with the increase of the temperature, the output current sampling voltage Vcs is compared with the reference voltage Vref, the signal is transmitted to the primary side through the negative feedback circuit, the control chip reduces the output current, and the power of the power supply is reduced, so as to reduce the temperature.

[0042] The above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A switching power supply temperature control circuit, directly connected to the secondary output terminal of a power supply, characterized in that, The application relates to a circuit for detecting the output current of a power supply, comprising: an external power supply voltage (VCC) and an output current sampling voltage (Vcs), the external power supply voltage (VCC) is connected to a reference circuit, a negative feedback circuit and an operational amplifier (U1) respectively; the reference circuit is connected to the positive input terminal of the operational amplifier (U1); the negative feedback circuit is connected to the negative input terminal and the output terminal of the operational amplifier (U1); the output current sampling voltage (Vcs) is connected to the negative input terminal of the operational amplifier (U1) through the negative feedback circuit; the operational amplifier (U1) is grounded.

2. The switching power supply temperature control circuit according to claim 1, wherein the reference circuit comprises a second resistor (R2) and a seventh resistor (R7), the external power supply voltage (VCC) is connected to the second resistor (R2), the seventh resistor (R7) and the output terminal of the operational amplifier (U1) respectively; the other end of the second resistor (R2) is connected to a thermistor (PTC) and the drain of a MOS tube (Q1) respectively; the other end of the seventh resistor (R7) and the gate of the MOS tube (Q1) are grounded through a temperature switch (S1); the other end of the thermistor (PTC) and the source of the MOS tube (Q1) are connected to a first resistor (R1) and the cathode of a stabilizing diode (ZD1) respectively; the other end of the first resistor (R1) is connected to a fourth resistor (R4) and the positive input terminal of the operational amplifier (U1) respectively; the other end of the fourth resistor (R4) and the anode of the stabilizing diode (ZD1) are grounded; the first capacitor (C1) is connected in parallel across the fourth resistor (R4).

3. The switching power supply temperature control circuit according to claim 1, wherein the negative feedback circuit comprises an eighth resistor (R8), the external power supply voltage (VCC) is connected to the input terminal of an optical coupler (OP1) through the eighth resistor (R8); the output terminal of the optical coupler (OP1) is connected to the anode of a diode (D1); the cathode of the diode (D1) is connected to a fifth resistor (R5); the other end of the fifth resistor (R5) is connected to the output terminal of the operational amplifier (U1) and a sixth resistor (R6) respectively; the other end of the sixth resistor (R6) is connected to a second capacitor (C2); the other end of the second capacitor (C2) is connected to a third resistor (R3) and the negative input terminal of the operational amplifier (U1) respectively; the third capacitor (C3) is connected in parallel across the sixth resistor (R6) and the second capacitor (C2); the output current sampling voltage (Vcs) is connected to the negative input terminal of the operational amplifier (U1) through the third resistor (R3).

4. The switching power supply temperature control circuit according to claim 1, wherein the reference circuit is used for providing a reference voltage Vref and comparing the reference voltage Vref with the output current sampling voltage (Vcs) through the operational amplifier.

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