Switching power supply circuit and power adapter

Abstract

The utility model discloses a switching power supply circuit and power adapter, switching power supply circuit includes filter circuit, current detection circuit, first switching circuit, voltage conversion circuit, temperature detection circuit, overvoltage protection circuit, first chip and second chip, through the introduction overvoltage protection circuit and temperature detection circuit, and with current detection circuit, first chip's output voltage feedback combines, will by second chip to input voltage, input current, output voltage, working temperature etc. multiple dimension parameters carry out the cooperative monitoring and processing to this control first switching circuit's on-off, thereby realizes the steady voltage output, overcurrent protection, overtemperature protection, overvoltage protection etc. multiple function, has promoted the comprehensive reliability and security of switching power supply circuit significantly.

Description

Technical Field

[0001] This utility model relates to the field of switching power supply technology, and in particular to a switching power supply circuit and power adapter. Background Technology

[0002] Switching power supplies are critical components in modern electronic devices, and their reliability is paramount. Traditional switching power supplies typically employ feedback loops to stabilize the output voltage and are equipped with basic protection functions such as overcurrent or short-circuit protection.

[0003] However, these traditional solutions have significant shortcomings: their protection mechanisms are singular and passive. They often only respond to output-side faults, lacking real-time, dedicated monitoring of input-side voltage anomalies and the operating temperatures of critical internal components. Input overvoltage can directly impact and damage the main switching transistors and capacitors, while localized overheating is a major cause of long-term power supply failure. Because they cannot simultaneously monitor multiple key parameters such as input voltage, input current, output voltage, and operating temperature in a coordinated manner, traditional power supplies are slow to react or make inaccurate judgments when facing complex operating conditions, exhibiting protection blind spots and insufficient overall system reliability and safety. Utility Model Content

[0004] This utility model provides a switching power supply circuit and a power adapter to address the issue of how to provide a switching power supply circuit that can simultaneously and in real time monitor multiple parameters such as input voltage, input current, output voltage, and operating temperature, and make coordinated judgments through an integrated control chip, thereby achieving fast and accurate multi-fault protection and fundamentally improving the reliability and safety of the switching power supply.

[0005] A switching power supply circuit includes a filter circuit, a current detection circuit, a first switching circuit, a voltage conversion circuit, a temperature detection circuit, an overvoltage protection circuit, a first chip, and a second chip. The filtering circuit is used to connect to the DC input terminal and is connected to the input terminal of the voltage conversion circuit. It is used to filter the electrical signal input to the DC input terminal. The output terminal of the voltage conversion circuit is used to connect to the load connection terminal. The current detection circuit and the first switching circuit are connected in series between the input terminals of the filter circuit and the voltage conversion circuit. The first chip is connected to the output terminal of the voltage conversion circuit and the second chip, and is used to detect the output voltage and output the output voltage to the second chip. The temperature detection circuit is connected to the voltage conversion circuit and the second chip, and is used to detect the operating temperature of the voltage conversion circuit and output the operating temperature to the second chip. The overvoltage protection circuit is connected to the input terminal of the voltage conversion circuit and the second chip, and is used to detect the input voltage. When the input voltage is greater than the preset voltage, it outputs an overvoltage protection signal to the second chip. The second chip is connected to the current detection circuit and the first switching circuit, and is used to control the first switching circuit to be turned on or off based on the output voltage, the operating temperature, the input voltage and the input current fed back by the current detection circuit.

[0006] Furthermore, the filter circuit includes a first resistor and two parallel capacitor circuits; each capacitor circuit includes two first capacitors connected in series; each first capacitor is connected in parallel with a first resistor.

[0007] Furthermore, the current detection circuit includes a plurality of first detection resistors; the plurality of first detection resistors are arranged in series and / or in parallel.

[0008] Furthermore, the first switching circuit includes a first switching transistor, a first terminal of the first switching transistor is coupled to the filter circuit, a second terminal of the first switching transistor is connected to the voltage conversion circuit, and a third terminal of the first switching transistor is connected to the second chip.

[0009] Furthermore, the voltage conversion circuit includes a transformer; the transformer includes a primary winding, a secondary winding, and an auxiliary winding; The first end of the primary winding is connected to the filter circuit, the second end of the primary winding is connected to the current detection circuit or the first switching circuit, and the secondary winding is used to connect to the load connection terminal. The first end of the auxiliary winding is connected to the second chip and the temperature detection circuit, and the second end of the auxiliary winding is connected to the first reference ground, for supplying power to the second chip and the temperature detection circuit.

[0010] Furthermore, the temperature detection circuit includes a thermistor, a second resistor, and a first diode; The thermistor, the second resistor, and the first diode are connected in series between the output terminal of the voltage conversion circuit and the second detection terminal of the second chip.

[0011] Furthermore, the overvoltage protection circuit includes a first voltage divider circuit, a first Zener diode, a second voltage divider circuit, and a first driving transistor; The first terminal of the first voltage divider circuit is connected to the input terminal of the voltage conversion circuit, the second terminal of the first voltage divider circuit is connected to the first reference ground, the third terminal of the first voltage divider circuit is connected to the cathode of the first Zener diode, the anode of the first Zener diode is connected to the first terminal of the second voltage divider circuit, the second terminal of the second voltage divider circuit is connected to the first reference ground, and the third terminal of the second voltage divider circuit is connected to the third terminal of the first driving transistor. The first end of the first driving transistor is connected to the second chip, and the second end of the first driving transistor is connected to the first reference ground.

[0012] Furthermore, the switching power supply circuit also includes a first optocoupler; The first optocoupler includes a phototransistor and a light-emitting diode; The anode of the light-emitting diode is connected to the first signal feedback terminal of the first chip, and the cathode of the light-emitting diode is connected to the second reference ground; The first end of the phototransistor is connected to the signal feedback terminal of the second chip, and the second end of the phototransistor is connected to the first reference ground.

[0013] Furthermore, the switching power supply circuit also includes a second detection resistor and a second switching transistor; The second sensing resistor and the second switching transistor are connected in series between the output terminal of the voltage conversion circuit and the load connection terminal; The first detection terminal of the first chip is connected to the output terminal of the voltage conversion circuit through the second detection resistor, and the first control terminal of the first chip is connected to the control terminal of the second switching transistor.

[0014] A power adapter comprising the aforementioned switching power supply circuit.

[0015] This utility model provides a switching power supply circuit and a power adapter. By introducing an overvoltage protection circuit and a temperature detection circuit, and combining them with a current detection circuit and the output voltage feedback of the first chip, the second chip will collaboratively monitor and process multiple parameters such as input voltage, input current, output voltage, and operating temperature, thereby controlling the on / off state of the first switching circuit. This achieves multiple functions such as voltage regulation, overcurrent protection, overtemperature protection, and overvoltage protection, significantly improving the overall reliability and safety of the switching power supply circuit. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a switching power supply circuit in one embodiment of the present invention.

[0018] In the diagram: 1. Filter circuit; 11. Two parallel capacitor circuits; 2. Current detection circuit; 3. First switching circuit; 4. Voltage conversion circuit; 5. Temperature detection circuit; 6. Overvoltage protection circuit; 61. First voltage divider circuit; 62. Second voltage divider circuit. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model.

[0020] It should be understood that this invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this invention to those skilled in the art.

[0021] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0022] To fully understand this utility model, detailed structures and steps will be presented in the following description to illustrate the technical solution proposed by this utility model. Preferred embodiments of this utility model are described in detail below; however, in addition to these detailed descriptions, this utility model may have other embodiments.

[0023] This embodiment provides a switching power supply circuit, such as Figure 1 As shown, the circuit includes a filter circuit 1, a current detection circuit 2, a first switching circuit 3, a voltage conversion circuit 4, a temperature detection circuit 5, an overvoltage protection circuit 6, a first chip U1, and a second chip U2. The filter circuit 1 is connected to the DC input terminal and the input terminal of the voltage conversion circuit 4, used to filter the electrical signal input from the DC input terminal. The output terminal of the voltage conversion circuit 4 is connected to the load connection terminal. The current detection circuit 2 and the first switching circuit 3 are connected in series between the filter circuit 1 and the input terminal of the voltage conversion circuit 4. The first chip U1 is connected to the output terminal of the voltage conversion circuit 4 and the second chip U2, used to detect the output voltage and output the output voltage. The temperature detection circuit 5 is connected to the voltage conversion circuit 4 and the second chip U2, and is used to detect the operating temperature of the voltage conversion circuit 4 and output the operating temperature to the second chip U2; the overvoltage protection circuit 6 is connected to the input terminal of the voltage conversion circuit 4 and the second chip U2, and is used to detect the input voltage, and output an overvoltage protection signal to the second chip U2 when the input voltage is greater than a preset voltage; the second chip U2 is connected to the current detection circuit 2 and the first switching circuit 3, and is used to control the first switching circuit 3 to be turned on or off according to the output voltage, the operating temperature, the input voltage and the input current fed back by the current detection circuit 2.

[0024] As an example, the input terminal of filter circuit 1 is connected to a DC input port, and the output terminal of filter circuit 1 is connected to the input terminal of voltage conversion circuit 4. Filter circuit 1 is used to smooth and filter the pulsed DC signal input to the DC input terminal, filtering out high-frequency noise and providing a clean DC signal for subsequent circuits. Optionally, the pulsed DC signal may be, for example, the DC signal processed by a rectifier bridge.

[0025] As an example, the current detection circuit 2 and the first switching circuit 3 are connected in series and arranged as a single circuit module between the input terminals of the filter circuit 1 and the voltage conversion circuit 4. The main power current of the switching power supply circuit flows sequentially through the current detection circuit 2 and the first switching circuit 3. The current detection circuit 2 is used to sample the input current flowing through it in real time and convert it into a voltage signal to be fed back to the second chip U2.

[0026] As an example, the output of voltage conversion circuit 4 is used to connect to the load connection terminal to provide a stable, isolated DC voltage to the electrical load (not shown).

[0027] As an example, the first chip U1 is connected to the output of the voltage conversion circuit 4 and the second chip U2. Optionally, the first chip U1 and the second chip U2 are indirectly connected through an isolation device. Exemplarily, this isolation signal is, for example, an optocoupler. In this example, the first chip U1 is used to detect the amplitude of the output voltage with high precision and generate an error signal based on the difference between the output voltage and an internal reference, which is transmitted to the second chip U2 through isolation. Optionally, the first chip U1 can be a feedback control chip on the secondary side.

[0028] As an example, the detection point of the temperature detection circuit 5 is located at a critical heat-generating component of the voltage conversion circuit 4. Optionally, this critical heat-generating component may be near the magnetic core of the transformer T1, the heat sink of the power switch transistor, etc. The temperature detection circuit 5 is connected to the second chip U2 to monitor the operating temperature of the voltage conversion circuit 4 in real time and outputs an analog signal representing the operating temperature to the second chip U2.

[0029] As an example, the input terminal of the overvoltage protection circuit 6 is connected to the input terminal of the voltage conversion circuit 4, i.e., to the filtered high-voltage DC bus, and the output terminal of the overvoltage protection circuit 6 is connected to the second chip U2. The overvoltage protection circuit 6 is used to continuously detect the amplitude of the input voltage. When the input voltage abnormally rises and exceeds a preset voltage threshold, the overvoltage protection circuit 6 will immediately generate an effective overvoltage protection signal and output it to the second chip U2. Exemplarily, the preset voltage is set by the internal component parameters of the overvoltage protection circuit 6.

[0030] As an example, the second chip U2 establishes electrical signal connections with the current detection circuit 2, the first switching circuit 3, the first chip U1, the temperature detection circuit 5, and the overvoltage protection circuit 6. The second chip U2 receives the output voltage feedback signal from the first chip U1, the operating temperature signal from the temperature detection circuit 5, the input overvoltage protection signal (i.e., the input voltage status signal) from the overvoltage protection circuit 6, and the input current sampling signal from the current detection circuit 2. The internal logic unit of the second chip U2 (or through external pin logic) comprehensively processes and judges the output voltage, the operating temperature, the input voltage, and the input current fed back by the current detection circuit 2. Based on the output voltage, the operating temperature, the input voltage, and the input current fed back by the current detection circuit 2, the second chip U2 generates a PWM (Pulse Width Modulation) control signal, which is output to the control terminal of the first switching circuit 3. This precisely controls the timing and duty cycle of the first switching circuit 3's on / off state, thereby achieving multiple functions such as regulated output, overcurrent protection (OCP), overtemperature protection (OTP), and overvoltage protection (OVP), realizing temperature-current dual closed-loop protection. Optionally, the second chip U2 is a master pulse modulation control chip on the primary side, such as the RT7755 series.

[0031] In this embodiment, by introducing an overvoltage protection circuit 6 and a temperature detection circuit 5, and combining them with the current detection circuit 2 and the output voltage feedback of the first chip U1, the second chip U2 will collaboratively monitor and process multiple parameters such as input voltage, input current, output voltage, and operating temperature, thereby controlling the on / off state of the first switching circuit 3. This achieves multiple functions such as voltage regulation, overcurrent protection, overtemperature protection, and overvoltage protection, significantly improving the overall reliability and safety of the switching power supply circuit.

[0032] In one embodiment, the filter circuit 1 includes a first resistor and two parallel capacitor circuits 11; each capacitor circuit includes two first capacitors connected in series; each first capacitor is connected in parallel with a first resistor. Figure 1 As shown, the first capacitor includes capacitors C1, C2, C3, and C4. The first resistor includes resistors R1, R2, R3, and R4. Capacitors C1 and C2 are connected in series, and capacitors C3 and C4 are connected in series. Resistor R1 is connected in parallel with capacitor C1, resistor R2 is connected in parallel with capacitor C2, resistor R3 is connected in parallel with capacitor C3, and resistor R4 is connected in parallel with capacitor C4.

[0033] In this embodiment, the filter circuit 1 includes a first resistor and two parallel capacitor circuits 11; each capacitor circuit includes two first capacitors connected in series; each first capacitor is connected in parallel with a first resistor, thereby reducing the voltage stress on a single first capacitor and reducing leakage current by connecting the first resistor in parallel.

[0034] In one embodiment, the current detection circuit 2 includes a plurality of first detection resistors; the plurality of first detection resistors are connected in series and / or in parallel. In this embodiment, the current detection circuit 2 includes a plurality of first detection resistors; the plurality of first detection resistors are connected in series and / or in parallel, and can be arranged in series, parallel, or a combination of series and parallel connections on the main power path according to actual power and accuracy requirements to sample the input current. In this example, the current detection circuit 2 includes one first detection resistor R5.

[0035] In one embodiment, the first switching circuit 3 includes a first switching transistor Q1, the first end of the first switching transistor Q1 is coupled to the filter circuit 1, the second end of the first switching transistor Q1 is connected to the voltage conversion circuit 4, and the third end of the first switching transistor Q1 is connected to the second chip U2.

[0036] As an example, the first switching transistor Q1 is a MOSFET. The source of the first switching transistor Q1 is coupled to the filter circuit 1, the drain of the first switching transistor Q1 is connected to the voltage conversion circuit 4, and the gate of the first switching transistor Q1 is connected to the PWM output pin GATE of the second chip U2 to receive the drive signal output by the second chip U2. Exemplarily, the PWM output pin GATE of the second chip U2 is connected to the gate of the first switching transistor Q1 through a resistor R8.

[0037] In one embodiment, the voltage conversion circuit 4 includes a transformer T1; the transformer T1 includes a primary winding NP, a secondary winding NS, and an auxiliary winding NA; the first end of the primary winding NP is connected to the filter circuit 1, the second end of the primary winding NP is connected to the current detection circuit 2 or the first switching circuit 3, the secondary winding NS is used to connect to the load connection terminal; the first end of the auxiliary winding NA is connected to the second chip U2 and the temperature detection circuit 5, the second end of the auxiliary winding NA is connected to the first reference ground PGND, and is used to supply power to the second chip U2 and the temperature detection circuit 5.

[0038] As an example, the voltage conversion circuit 440 includes a transformer T1. Transformer T1 includes a primary winding NP, a secondary winding NS, and an auxiliary winding NA. The first terminal of the primary winding NP is connected to the output of the filter circuit 110, and the second terminal of the primary winding NP is connected to the drain of the first switching transistor Q1. The secondary winding NS is connected to the load connection terminal through a rectifier and filter element (not shown in detail). The first terminal of the auxiliary winding NA is rectified and filtered by resistor R6, capacitor C6, diode D2, and resistor R12 to generate a supply voltage, which powers the primary-side circuits such as the second chip U2 and the temperature detection circuit 5; the second terminal of the auxiliary winding NA is connected to the primary-side first reference ground PGND.

[0039] In one embodiment, the temperature detection circuit 5 includes a thermistor RT1, a second resistor R10, and a first diode D1; the thermistor RT1, the second resistor R10, and the first diode D1 are connected in series between the output terminal of the voltage conversion circuit 4 and the second detection terminal CS of the second chip U2.

[0040] As an example, the temperature detection circuit 5 includes a negative temperature coefficient thermistor RT1, a second resistor R10, and a first diode D1. The second resistor R10 is used for current limiting, and the first diode D1 is used for isolation. The thermistor RT1, the second resistor R10, and the first diode D1 are connected in series between the auxiliary winding NA supply voltage and the second detection terminal CS of the second chip U2. When the temperature rises, the resistance of the thermistor RT1 decreases, causing the voltage input to the second detection terminal CS of the second chip U2 to increase. When this voltage exceeds an internal threshold, protection is triggered.

[0041] For example, the second detection terminal CS of the second chip U2 is connected to the first detection resistor R5 in the current detection circuit 2 through resistor R9, thereby achieving temperature-current dual closed-loop protection in combination with the operating temperature fed back by the temperature detection circuit 5.

[0042] In one embodiment, the overvoltage protection circuit 6 includes a first voltage divider circuit 61, a first Zener diode ZD1, a second voltage divider circuit 62, and a first driving transistor Q3. The first terminal of the first voltage divider circuit 61 is connected to the input terminal of the voltage conversion circuit 4. The second terminal of the first voltage divider circuit 61 is connected to the first reference ground PGND. The third terminal of the first voltage divider circuit 61 is connected to the cathode of the first Zener diode ZD1. The anode of the first Zener diode ZD1 is connected to the first terminal of the second voltage divider circuit 62. The second terminal of the second voltage divider circuit 62 is connected to the first reference ground PGND. The third terminal of the second voltage divider circuit 62 is connected to the third terminal of the first driving transistor Q3. The first terminal of the first driving transistor Q3 is connected to the second chip U2, and the second terminal of the first driving transistor Q3 is connected to the first reference ground PGND.

[0043] As an example, the first voltage divider circuit 61 includes a first voltage divider resistor R16 and a second voltage divider resistor R17. The first voltage divider resistor R16 and the second voltage divider resistor R17 are connected in series between the input terminal of the voltage conversion circuit 4 and the first reference ground PGND. The connection node between the first voltage divider resistor R16 and the second voltage divider resistor R17 is connected to the cathode of the first Zener diode ZD1.

[0044] As an example, the second voltage divider circuit 62 includes a second voltage divider resistor R18 and a third voltage divider resistor R19. The second voltage divider resistor R18 and the third voltage divider resistor R19 are connected in series between the anode of the first Zener diode ZD1 and the first reference ground PGND. The connection node between the second voltage divider resistor R18 and the third voltage divider resistor R19 is connected to the third terminal of the first driving transistor Q3.

[0045] As an example, the first driving transistor Q3 is a bipolar transistor. The first terminal of the first driving transistor Q3 is the collector, the second terminal of the first driving transistor Q3 is the emitter, and the third terminal of the first driving transistor Q3 is the base.

[0046] As an example, the overvoltage protection circuit 6 includes a first voltage divider circuit 61, a first Zener diode ZD1, a second voltage divider circuit 62, and a first driver transistor Q3. The first voltage divider circuit 61 divides the input voltage. The voltage divider point of the first voltage divider circuit 61 is connected to the cathode of the first Zener diode ZD1. When the voltage divided by the first voltage divider circuit 61 is lower than the Zener voltage of the first Zener diode ZD1, the first Zener diode ZD1 is cut off, and the circuit has no output. When the input voltage is too high, causing the voltage divided by the first voltage divider circuit 61 to break down the first Zener diode ZD1, the first Zener diode ZD1 conducts. Current flows through the second voltage divider circuit 62, generating a voltage drop across the first driver transistor Q3, driving the first driver transistor Q3 to conduct. This pulls the collector potential of the first driver transistor Q3 down to the first reference ground PGND. The collector of the first driver transistor Q3 is connected to the signal feedback terminal COMP of the second chip U2. A low-level active signal causes the second chip U2 to stop outputting, thus achieving protection. For example, the collector of the first driving transistor Q3 is connected to the signal feedback terminal COMP of the second chip U2 through resistor R20.

[0047] In one embodiment, the switching power supply circuit further includes a first optocoupler; the first optocoupler includes a phototransistor U3B and a light-emitting diode U3A; the anode of the light-emitting diode U3A is connected to the first signal feedback terminal of the first chip U1, and the cathode of the light-emitting diode U3A is connected to the second reference ground SGND; the first terminal of the phototransistor U3B is connected to the signal feedback terminal of the second chip U2, and the second terminal of the phototransistor U3B is connected to the first reference ground PGND.

[0048] In this embodiment, the anode of LED U3A is connected to the first signal feedback terminal OPTO of the first chip U1 through a current-limiting resistor R15, and the cathode of LED U3A is connected to the second reference ground SGND on the secondary side. The first terminal (collector) of phototransistor U3B is connected to the signal feedback terminal COMP of the second chip U2, and the second terminal (emitter) of phototransistor U3B is connected to the first reference ground PGND on the primary side. Thus, the voltage error signal on the secondary side is transmitted to the second chip U2 on the primary side in an isolated manner through the first optocoupler.

[0049] In one embodiment, the switching power supply circuit further includes a second detection resistor R13 and a second switching transistor Q2; the second detection resistor R13 and the second switching transistor Q2 are connected in series between the output terminal of the voltage conversion circuit 4 and the load connection terminal; the first detection terminal of the first chip U1 is connected to the output terminal of the voltage conversion circuit 4 through the second detection resistor R13, and the first control terminal USBP of the first chip U1 is connected to the control terminal of the second switching transistor Q2.

[0050] As an example, the second switch Q2 is a MOSFET. The first terminal of the second sensing resistor R13 is connected to the output terminal of the voltage conversion circuit 4, the second terminal of the second sensing resistor R13 is connected to the drain of the second switch Q2, the source of the second switch Q2 is connected to the load connection terminal, and the gate of the second switch Q2 is connected to the first control terminal USBP of the first chip U1 through resistor R14. The first sensing terminal of the first chip U1 includes a CS+ terminal and a CS- terminal. The CS+ terminal is connected to the first terminal of the second sensing resistor R13, and the CS- terminal is connected to the second terminal of the second sensing resistor R13. Exemplarily, the power supply terminal VDD of the first chip U1 is connected to the output terminal of the voltage conversion circuit 4.

[0051] In this embodiment, the second sensing resistor R13 and the second switching transistor Q2 are connected in series between the output terminal and the load connection terminal of the voltage conversion circuit 4. The first sensing terminal of the first chip U1 is connected to the output terminal of the voltage conversion circuit 4 through the second sensing resistor R13 to accurately detect the output voltage. At the same time, the first chip U1 can control the gate of the second switching transistor Q2 through the first control terminal, for example, when more complex control functions such as soft start and overload circuit breaking are required on the secondary side.

[0052] This embodiment provides a power adapter, including the switching power supply circuit described above.

[0053] The above-described embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be included within the protection scope of this utility model.

Claims

1. A switching power supply circuit, characterized in that, It includes a filter circuit, a current detection circuit, a first switching circuit, a voltage conversion circuit, a temperature detection circuit, an overvoltage protection circuit, a first chip, and a second chip; The filtering circuit is used to connect to the DC input terminal and is connected to the input terminal of the voltage conversion circuit. It is used to filter the electrical signal input to the DC input terminal. The output terminal of the voltage conversion circuit is used to connect to the load connection terminal. The current detection circuit and the first switching circuit are connected in series between the input terminals of the filter circuit and the voltage conversion circuit. The first chip is connected to the output terminal of the voltage conversion circuit and the second chip, and is used to detect the output voltage and output the output voltage to the second chip. The temperature detection circuit is connected to the voltage conversion circuit and the second chip, and is used to detect the operating temperature of the voltage conversion circuit and output the operating temperature to the second chip. The overvoltage protection circuit is connected to the input terminal of the voltage conversion circuit and the second chip, and is used to detect the input voltage. When the input voltage is greater than the preset voltage, it outputs an overvoltage protection signal to the second chip. The second chip is connected to the current detection circuit and the first switching circuit, and is used to control the first switching circuit to be turned on or off based on the output voltage, the operating temperature, the input voltage and the input current fed back by the current detection circuit.

2. The switching power supply circuit as described in claim 1, characterized in that, The filter circuit includes a first resistor and two parallel capacitor circuits; each capacitor circuit includes two first capacitors connected in series; each first capacitor is connected in parallel with a first resistor.

3. The switching power supply circuit as described in claim 1, characterized in that, The current detection circuit includes a plurality of first detection resistors; the plurality of first detection resistors are arranged in series and / or in parallel.

4. The switching power supply circuit as described in claim 1, characterized in that, The first switching circuit includes a first switching transistor, a first terminal of which is coupled to the filter circuit, a second terminal of which is connected to the voltage conversion circuit, and a third terminal of which is connected to the second chip.

5. The switching power supply circuit as described in claim 1, characterized in that, The voltage conversion circuit includes a transformer; the transformer includes a primary winding, a secondary winding, and an auxiliary winding; The first end of the primary winding is connected to the filter circuit, the second end of the primary winding is connected to the current detection circuit or the first switching circuit, and the secondary winding is used to connect to the load connection terminal. The first end of the auxiliary winding is connected to the second chip and the temperature detection circuit, and the second end of the auxiliary winding is connected to the first reference ground, for supplying power to the second chip and the temperature detection circuit.

6. The switching power supply circuit as described in claim 1, characterized in that, The temperature detection circuit includes a thermistor, a second resistor, and a first diode; The thermistor, the second resistor, and the first diode are connected in series between the output terminal of the voltage conversion circuit and the second detection terminal of the second chip.

7. The switching power supply circuit as described in claim 1, characterized in that, The overvoltage protection circuit includes a first voltage divider circuit, a first Zener diode, a second voltage divider circuit, and a first driver diode; The first terminal of the first voltage divider circuit is connected to the input terminal of the voltage conversion circuit, the second terminal of the first voltage divider circuit is connected to the first reference ground, the third terminal of the first voltage divider circuit is connected to the cathode of the first Zener diode, the anode of the first Zener diode is connected to the first terminal of the second voltage divider circuit, the second terminal of the second voltage divider circuit is connected to the first reference ground, and the third terminal of the second voltage divider circuit is connected to the third terminal of the first driving transistor. The first end of the first driving transistor is connected to the second chip, and the second end of the first driving transistor is connected to the first reference ground.

8. The switching power supply circuit as described in claim 1, characterized in that, The switching power supply circuit also includes a first optocoupler; The first optocoupler includes a phototransistor and a light-emitting diode; The anode of the light-emitting diode is connected to the first signal feedback terminal of the first chip, and the cathode of the light-emitting diode is connected to the second reference ground; The first end of the phototransistor is connected to the signal feedback terminal of the second chip, and the second end of the phototransistor is connected to the first reference ground.

9. The switching power supply circuit as described in claim 1, characterized in that, The switching power supply circuit also includes a second detection resistor and a second switching transistor. The second sensing resistor and the second switching transistor are connected in series between the output terminal of the voltage conversion circuit and the load connection terminal; The first detection terminal of the first chip is connected to the output terminal of the voltage conversion circuit through the second detection resistor, and the first control terminal of the first chip is connected to the control terminal of the second switching transistor.

10. A power adapter, characterized in that, Includes the switching power supply circuit according to any one of claims 1 to 9.

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