Switching power supply control circuit with controlled single-path output

Abstract

The invention provides a switching power supply control circuit with controlled single-path output, and relates to the field of power supply control circuits, and the switching power supply control circuit with controlled single-path output comprises an input terminal, a PWM circuit, a control circuit, a transformation circuit, an output terminal, a control circuit EN signal feedback circuit, and a VCC power supply circuit. The characteristic that the FB pin of the PWM circuit turns off PWM output at a low level is utilized, low power consumption, low cost and no noise are achieved, the FB pin of the PWM circuit is pulled to the low level, so that an IC cannot normally drive to achieve controllable output, and the circuit has the advantages of being capable of saving material cost, low in power consumption, capable of reducing the wiring space of a PCB, good in reliability and the like.

Description

Technical Field

[0001] The present application relates to the field of power supply control circuits, and in particular to a single-channel output controlled switching power supply control circuit. Background Art

[0002] Traditional single-channel output switching power supplies want to output the on / off control of the controlled circuit by connecting a relay in series at the output end. When the control circuit is at a high level, the relay coil is powered to close the relay and the output is used to power the subsequent equipment. Alternatively, a P-MOS is connected in series to replace the relay. Neither of these two methods can achieve low power consumption and low cost by shutting down the PWM IC. First, the relay solution produces noise when the relay is turned on and off. The relay is expensive and large in size. When overcurrent and short circuit occur in the downstream electrical equipment, the relay contacts will heat up and stick and fail. The P-MOS solution is also costly, and heat sinks are required for those with slightly higher power. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a single-output controlled switching power supply control circuit, which can solve the above-mentioned technical problems.

[0004] An embodiment of the present application provides a single-channel output controlled switching power supply control circuit, comprising an input terminal, a PWM circuit, a control circuit, a voltage conversion circuit, an output terminal, a control circuit EN signal feedback circuit, and a VCC power supply circuit, wherein the input end of the input terminal is connected to an external battery assembly, the output end of the input terminal is connected to the input end of the PWM circuit, the output end of the PWM circuit is connected to the input end of the voltage conversion circuit and the input end of the control circuit, the output end of the voltage conversion circuit is connected to the output terminal, the input end of the control circuit EN signal feedback circuit is connected to the output end of the voltage circuit through the VCC power supply circuit, the output end of the control circuit EN signal feedback circuit is electrically connected to the control circuit, and the output end of the VCC power supply circuit is electrically connected to the PWM circuit.

[0005] Preferably, the PWM circuit includes a variable resistor MOV1, a conjugate inductor LF1, a capacitor CX1, a resistor R1, a resistor R2, a conjugate inductor LF2, a diode D1, a diode D2, a rectifier bridge, a capacitor CC1, a capacitor CC2, a resistor R7, and a capacitor EC1, one end of the variable resistor MOV1 is connected to the input terminal and the third port of the conjugate inductor LF1, the other end of the variable resistor MOV1 is connected to the input terminal and the first port of the conjugate inductor LF1, the fourth interface of the conjugate inductor LF1 is connected to one end of the capacitor CX1, one end of the resistor R1, and the third interface of the conjugate inductor LF2, the second interface of the conjugate inductor LF1 is connected to the other end of the capacitor CX1, one end of the resistor R2, and the first interface of the conjugate inductor LF2, and the resistor R 1 is connected to the other end of the resistor R2, the second interface of the conjugate inductor LF2 is connected to the input end of the diode D2 and the third interface of the rectifier bridge, the fourth interface of the conjugate inductor LF2 is connected to the second interface of the rectifier bridge, the fourth interface of the conjugate inductor LF2 and the second interface of the rectifier bridge are both connected to the control circuit through the diode D1, the first interface of the rectifier bridge is connected to one end of the capacitor CC1, the fourth interface of the rectifier bridge is connected to the other end of the capacitor CC1 and the other end of the capacitor CC2, one end of the resistor R7 is connected to the first interface of the rectifier bridge, the other end of the resistor R7 is connected to the other end of the capacitor CC2, the capacitor EC1 is connected to one end of the resistor R7 and the transformer circuit, and the other end of the capacitor EC1 is grounded.

[0006] Preferably, the voltage transformation circuit includes a voltage stabilizing and current limiting circuit, a transformer, a diode D5, a diode D6, a resistor R35, a resistor R36, a resistor R33, a resistor R34, a resistor R37, a capacitor CC5, a capacitor C6, a capacitor EC3, a capacitor EC4, and a conjugate inductor LF3. The input end of the voltage stabilizing and current limiting circuit is connected to the PWM circuit, and the output end of the voltage stabilizing and current limiting circuit is connected to the primary coil of the transformer. One end of the secondary coil of the transformer is respectively connected to the input end of the diode D5, the input end of the diode D6, one end of the resistor R33, one end of the resistor R34, one end of the resistor R35, one end of the resistor R36, and one end of the capacitor C6. The output end of the diode D5, the The output end of the diode D6 is connected to one end of the capacitor CC5, one end of the capacitor EC3, one end of the capacitor EC4, and the third interface of the conjugate inductor LF3. The other end of the resistor R33, the other end of the resistor R34, the other end of the resistor R35, and the other end of the resistor R36 are connected to the other end of the capacitor CC5. The other end of the capacitor C6 is connected to one end of the resistor R37, and the other end of the resistor R37 is connected to one end of CC5. The other end of the capacitor EC3, the other end of the capacitor EC4, and the first interface of the conjugate inductor LF3 are all grounded. The second interface of the conjugate inductor LF3 and the fourth interface of the conjugate inductor LF3 are connected to the output terminal.

[0007] Preferably, the control circuit EN signal feedback circuit includes a terminal CON3, a resistor R44, a resistor R45, a resistor R46, a capacitor C7, a photoelectric coupling switch, a resistor R31, a resistor R28, a resistor R9, a resistor R26, a capacitor C2, and a transistor Q3. The third interface and the fourth interface of the terminal CON3 are connected to the control circuit, the first interface and the second interface of the terminal CON3 are both grounded, the fourth interface of the terminal CON3 is connected to one end of the resistor R46, the other end of the resistor R46 is connected to one end of the resistor R44, one end of the capacitor C7, and one end of the input end of the photoelectric coupling switch, the other end of the resistor R44, the The other end of the capacitor C7 and the other end of the input end of the photoelectric coupling switch are both grounded through the capacitor R45, one end of the output end of the photoelectric coupling switch is connected to the control circuit through the resistor R31 and the resistor R26, the other end of the output end of the photoelectric coupling switch is grounded, one end of the resistor R27 is connected to one end of the resistor R31, the other end of the resistor R27 is connected to one end of the resistor R28, one end of the capacitor C2, and the B pole of the transistor Q3, the other end of the capacitor C2, the other end of the resistor R28, and the E pole of the transistor Q3 are all grounded, and the C pole of the transistor Q3 is connected to the control circuit through the resistor R9.

[0008] Preferably, a fuse F1 and a thermistor NTC1 are provided between the input terminal and the PWM circuit.

[0009] Preferably, the output voltage of the output terminal is DC +24V.

[0010] Preferably, the VCC power supply circuit includes resistor R20, capacitor C1, capacitor EC2, diode D3, resistor R15, resistor R14, transistor Q1, transistor Q2, capacitor CC4, resistor R16, resistor R17, resistor R18, resistor R19, diode D4, capacitor C4, resistor R21, resistor R22, resistor R23, and resistor R25.

[0011] Preferably, the transformer comprises an auxiliary winding, and the auxiliary winding is electrically connected to the capacitor EC2.

[0012] Beneficial effects of the present invention:

[0013] The present invention provides a single-channel output controlled switching power supply control circuit, comprising an input terminal, a PWM circuit, a control circuit, a voltage conversion circuit, an output terminal, a control circuit EN signal feedback circuit, and a VCC power supply circuit. The input end of the input terminal is connected to an external battery assembly, the output end of the input terminal is connected to the input end of the PWM circuit, the output end of the PWM circuit is connected to the input end of the voltage conversion circuit and the input end of the control circuit, the output end of the voltage conversion circuit is connected to the output terminal, the input end of the control circuit EN signal feedback circuit is connected to the output end of the voltage circuit through the VCC power supply circuit, the output end of the control circuit EN signal feedback circuit is electrically connected to the control circuit, and the output end of the VCC power supply circuit is electrically connected to the PWM circuit. The present invention utilizes the characteristics of the FB pin of the PWM circuit turning off the PWM output at a low level to achieve low power consumption, low cost, and no noise. The circuit pulls the FB pin of the PWM circuit to a low level so that the IC cannot normally drive to achieve output control. This circuit can save material cost, has low power consumption, reduces PCB wiring space, and has good reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 It is a framework diagram of the present invention;

[0016] Figure 2 It is a circuit schematic diagram of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0019] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0020] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0021] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0022] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0023] like Figure 1-2 As shown, a single-channel output controlled switching power supply control circuit includes an input terminal, a PWM circuit, a control circuit, a voltage conversion circuit, an output terminal, a control circuit EN signal feedback circuit, and a VCC power supply circuit. The input end of the input terminal is connected to an external battery assembly, the output end of the input terminal is connected to the input end of the PWM circuit, the output end of the PWM circuit is connected to the input end of the voltage conversion circuit and the input end of the control circuit, the output end of the voltage conversion circuit is connected to the output terminal, the input end of the control circuit EN signal feedback circuit is connected to the output end of the voltage circuit through the VCC power supply circuit, the output end of the control circuit EN signal feedback circuit is electrically connected to the control circuit, and the output end of the VCC power supply circuit is electrically connected to the PWM circuit; the present invention utilizes the characteristics of the FB pin of the PWM circuit being low-level to shut down the PWM output, so as to achieve low power consumption, low cost, and no noise. The circuit pulls the FB pin of the PWM circuit to a low level so that the IC cannot drive normally to achieve output controllability. This circuit can save material cost, has low power consumption, reduces PCB wiring space, and has good reliability.

[0024] like Figure 2As shown, in this embodiment, the PWM circuit includes a variable resistor MOV1, a conjugate inductor LF1, a capacitor CX1, a resistor R1, a resistor R2, a conjugate inductor LF2, a diode D1, a diode D2, a rectifier bridge, a capacitor CC1, a capacitor CC2, a resistor R7, and a capacitor EC1. One end of the variable resistor MOV1 is connected to the input terminal and the third port of the conjugate inductor LF1, the other end of the variable resistor MOV1 is connected to the input terminal and the first port of the conjugate inductor LF1, the fourth interface of the conjugate inductor LF1 is connected to one end of the capacitor CX1, one end of the resistor R1, and the third interface of the conjugate inductor LF2, the second interface of the conjugate inductor LF1 is connected to the other end of the capacitor CX1, one end of the resistor R2, and the first interface of the conjugate inductor LF2, and the The other end of the resistor R1 is connected to the other end of the resistor R2, the second interface of the conjugate inductor LF2 is connected to the input end of the diode D2 and the third interface of the rectifier bridge, the fourth interface of the conjugate inductor LF2 is connected to the second interface of the rectifier bridge, the fourth interface of the conjugate inductor LF2 and the second interface of the rectifier bridge are both connected to the control circuit through the diode D1, the first interface of the rectifier bridge is connected to one end of the capacitor CC1, the fourth interface of the rectifier bridge is connected to the other end of the capacitor CC1 and the other end of the capacitor CC2, one end of the resistor R7 is connected to the first interface of the rectifier bridge, the other end of the resistor R7 is connected to the other end of the capacitor CC2, the capacitor EC1 is connected to one end of the resistor R7 and the transformer circuit, and the other end of the capacitor EC1 is grounded.

[0025] like Figure 2As shown, in this embodiment, the voltage conversion circuit includes a voltage stabilizing and current limiting circuit, a transformer, a diode D5, a diode D6, a resistor R35, a resistor R36, a resistor R33, a resistor R34, a resistor R37, a capacitor CC5, a capacitor C6, a capacitor EC3, a capacitor EC4, and a conjugate inductor LF3. The input end of the voltage stabilizing and current limiting circuit is connected to the PWM circuit, and the output end of the voltage stabilizing and current limiting circuit is connected to the primary coil of the transformer. One end of the secondary coil of the transformer is respectively connected to the input end of the diode D5, the input end of the diode D6, one end of the resistor R33, one end of the resistor R34, one end of the resistor R35, one end of the resistor R36, and one end of the capacitor C6. The output end of the diode D5 , the output end of the diode D6 is connected to one end of the capacitor CC5, one end of the capacitor EC3, one end of the capacitor EC4, and the third interface of the conjugate inductor LF3, the other end of the resistor R33, the other end of the resistor R34, the other end of the resistor R35, and the other end of the resistor R36 are connected to the other end of the capacitor CC5, the other end of the capacitor C6 is connected to one end of the resistor R37, and the other end of the resistor R37 is connected to one end of CC5, the other end of the capacitor EC3, the other end of the capacitor EC4, and the first interface of the conjugate inductor LF3 are all grounded, and the second interface of the conjugate inductor LF3 and the fourth interface of the conjugate inductor LF3 are connected to the output terminal.

[0026] like Figure 2As shown, in this embodiment, the control circuit EN signal feedback circuit includes a terminal CON3, a resistor R44, a resistor R45, a resistor R46, a capacitor C7, a photoelectric coupling switch, a resistor R31, a resistor R28, a resistor R9, a resistor R26, a capacitor C2, and a transistor Q3. The third interface and the fourth interface of the terminal CON3 are connected to the control circuit, the first interface and the second interface of the terminal CON3 are both grounded, the fourth interface of the terminal CON3 is connected to one end of the resistor R46, the other end of the resistor R46 is connected to one end of the resistor R44, one end of the capacitor C7, and one end of the input end of the photoelectric coupling switch, and the other end of the resistor R44, The other end of the capacitor C7 and the other end of the input end of the photoelectric coupling switch are both grounded through the capacitor R45, one end of the output end of the photoelectric coupling switch is connected to the control circuit through the resistor R31 and the resistor R26, the other end of the output end of the photoelectric coupling switch is grounded, one end of the resistor R27 is connected to one end of the resistor R31, the other end of the resistor R27 is connected to one end of the resistor R28, one end of the capacitor C2, and the B pole of the transistor Q3, the other end of the capacitor C2, the other end of the resistor R28, and the E pole of the transistor Q3 are all grounded, and the C pole of the transistor Q3 is connected to the control circuit through the resistor R9.

[0027] like Figure 2 As shown, in this embodiment, a fuse F1 and a thermistor NTC1 are provided between the input terminal and the PWM circuit.

[0028] like Figure 2 As shown, in this embodiment, the output voltage of the output terminal is DC +24V.

[0029] like Figure 2 As shown, in this embodiment, the VCC power supply circuit includes a resistor R20, a capacitor C1, a capacitor EC2, a diode D3, a resistor R15, a resistor R14, a transistor Q1, a transistor Q2, a capacitor CC4, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a diode D4, a capacitor C4, a resistor R21, a resistor R22, a resistor R23, and a resistor R25.

[0030] like Figure 2 As shown, in this embodiment, the transformer includes an auxiliary winding, and the auxiliary winding is electrically connected to the capacitor EC2.

[0031] This circuit has only a single 24V output voltage, which is turned on or off by the terminal product control circuit:

[0032] Open loop: When the EN pin of terminal CON3 receives a high-level signal from the control circuit, the photoelectric coupling switch is divided by resistors R44 and R45, and then the photoelectric coupling switch emits light, OC2B is turned on to pull down the upper end level of resistor R31, so that the base level of transistor Q3 also becomes low, and transistor Q3 is not turned on. The FB pin voltage of the control circuit remains normal, and the control circuit can turn on PWM to the gate of Q1, and 24V can be output normally.

[0033] Shutdown loop: When the control circuit sends a low-level signal to the EN pin of terminal CON3, the optocoupler switch does not work, and OC2B does not receive the signal to be cut off. The control circuit provides the working voltage through the high-voltage start pin of HV, and the gate of transistor Q1 turns on the PWM signal. At this time, the auxiliary winding of the transformer charges the capacitor EC2, and the VCC voltage is divided by resistors R26, R27, and R28 to provide voltage to the base of transistor Q3. After transistor Q3 is turned on, the level of the FB pin of the control circuit is pulled to the ground through resistor R9. At this time, the control circuit cannot detect the FB feedback signal, and the PWM signal is turned off to realize the 24V shutdown. When the VCC voltage on capacitor EC2 is consumed and Q3 is turned off, it will enter the next cycle, and 24V will always maintain the shutdown state.

[0034] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A single-output controlled switching power supply control circuit, characterized in that: It includes an input terminal, a PWM circuit, a control circuit, a voltage conversion circuit, an output terminal, a control circuit EN signal feedback circuit, and a VCC power supply circuit. The input end of the input terminal is connected to an external battery assembly, the output end of the input terminal is connected to the input end of the PWM circuit, the output end of the PWM circuit is connected to the input end of the voltage conversion circuit and the input end of the control circuit, the output end of the voltage conversion circuit is connected to the output terminal, the input end of the control circuit EN signal feedback circuit is connected to the output end of the voltage circuit through the VCC power supply circuit, the output end of the control circuit EN signal feedback circuit is electrically connected to the control circuit, and the output end of the VCC power supply circuit is electrically connected to the PWM circuit.

2. A single-output controlled switching power supply control circuit according to claim 1, characterized in that: The PWM circuit includes a variable resistor MOV1, a conjugate inductor LF1, a capacitor CX1, a resistor R1, a resistor R2, a conjugate inductor LF2, a diode D1, a diode D2, a rectifier bridge, a capacitor CC1, a capacitor CC2, a resistor R7, and a capacitor EC1. One end of the variable resistor MOV1 is connected to the input terminal and the third port of the conjugate inductor LF1. The other end of the variable resistor MOV1 is connected to the input terminal and the first port of the conjugate inductor LF1. The fourth interface of the conjugate inductor LF1 is connected to one end of the capacitor CX1, one end of the resistor R1, and the third interface of the conjugate inductor LF2. The second interface of the conjugate inductor LF1 is connected to the other end of the capacitor CX1, one end of the resistor R2, and the first interface of the conjugate inductor LF2. The other end is connected to the other end of the resistor R2, the second interface of the conjugate inductor LF2 is connected to the input end of the diode D2 and the third interface of the rectifier bridge, the fourth interface of the conjugate inductor LF2 is connected to the second interface of the rectifier bridge, the fourth interface of the conjugate inductor LF2 and the second interface of the rectifier bridge are both connected to the control circuit through the diode D1, the first interface of the rectifier bridge is connected to one end of the capacitor CC1, the fourth interface of the rectifier bridge is connected to the other end of the capacitor CC1 and the other end of the capacitor CC2, one end of the resistor R7 is connected to the first interface of the rectifier bridge, the other end of the resistor R7 is connected to the other end of the capacitor CC2, the capacitor EC1 is connected to one end of the resistor R7 and the transformer circuit, and the other end of the capacitor EC1 is grounded.

3. The single-output controlled switching power supply control circuit according to claim 1, characterized in that: The voltage transformation circuit includes a voltage stabilizing and current limiting circuit, a transformer, a diode D5, a diode D6, a resistor R35, a resistor R36, a resistor R33, a resistor R34, a resistor R37, a capacitor CC5, a capacitor C6, a capacitor EC3, a capacitor EC4, and a conjugate inductor LF3. The input end of the voltage stabilizing and current limiting circuit is connected to the PWM circuit, and the output end of the voltage stabilizing and current limiting circuit is connected to the primary coil of the transformer. One end of the secondary coil of the transformer is respectively connected to the input end of the diode D5, the input end of the diode D6, one end of the resistor R33, one end of the resistor R34, one end of the resistor R35, one end of the resistor R36, and one end of the capacitor C6. The output end of the diode D5, the diode D6, the resistor R33, the resistor R34, the resistor R35, the resistor R36, and the capacitor C6. The output end of the tube D6 is connected to one end of the capacitor CC5, one end of the capacitor EC3, one end of the capacitor EC4, and the third interface of the conjugate inductor LF3. The other end of the resistor R33, the other end of the resistor R34, the other end of the resistor R35, and the other end of the resistor R36 are connected to the other end of the capacitor CC5. The other end of the capacitor C6 is connected to one end of the resistor R37, and the other end of the resistor R37 is connected to one end of CC5. The other end of the capacitor EC3, the other end of the capacitor EC4, and the first interface of the conjugate inductor LF3 are all grounded. The second interface of the conjugate inductor LF3 and the fourth interface of the conjugate inductor LF3 are connected to the output terminal.

4. The single-output controlled switching power supply control circuit according to claim 1, characterized in that: The control circuit EN signal feedback circuit includes a terminal CON3, a resistor R44, a resistor R45, a resistor R46, a capacitor C7, a photoelectric coupling switch, a resistor R31, a resistor R28, a resistor R9, a resistor R26, a capacitor C2, and a transistor Q3. The third interface and the fourth interface of the terminal CON3 are connected to the control circuit. The first interface and the second interface of the terminal CON3 are both grounded. The fourth interface of the terminal CON3 is connected to one end of the resistor R46. The other end of the resistor R46 is connected to one end of the resistor R44, one end of the capacitor C7, and one end of the input end of the photoelectric coupling switch. The other end of the resistor R44, the capacitor C7, and the input end of the photoelectric coupling switch are connected. The other end of C7 and the other end of the input end of the photoelectric coupling switch are both grounded through the capacitor R45, one end of the output end of the photoelectric coupling switch is connected to the control circuit through the resistor R31 and the resistor R26, the other end of the output end of the photoelectric coupling switch is grounded, one end of the resistor R27 is connected to one end of the resistor R31, the other end of the resistor R27 is connected to one end of the resistor R28, one end of the capacitor C2, and the B pole of the transistor Q3, the other end of the capacitor C2, the other end of the resistor R28, and the E pole of the transistor Q3 are all grounded, and the C pole of the transistor Q3 is connected to the control circuit through the resistor R9.

5. The single-output controlled switching power supply control circuit according to claim 1, characterized in that: A fuse F1 and a thermistor NTC1 are provided between the input terminal and the PWM circuit.

6. The single-output controlled switching power supply control circuit according to claim 1, characterized in that: The output voltage of the output terminal is DC +24V.

7. The single-output controlled switching power supply control circuit according to claim 3, characterized in that: The VCC power supply circuit includes a resistor R20, a capacitor C1, a capacitor EC2, a diode D3, a resistor R15, a resistor R14, a transistor Q1, a transistor Q2, a capacitor CC4, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a diode D4, a capacitor C4, a resistor R21, a resistor R22, a resistor R23, and a resistor R25.

8. The single-output controlled switching power supply control circuit according to claim 7, characterized in that: The transformer includes an auxiliary winding, and the auxiliary winding is electrically connected to the capacitor EC2.

Images