Flyback switching power supply control circuit

Abstract

The utility model discloses a flyback switching power supply control circuit, and belongs to the technical field of power supply control. A pin 1 of a primary side of a transformer T1 is connected with an input end of external equipment, the pin 1 of the primary side of the transformer T1 is connected with an input end of a step-down sub-circuit, a pin 3 of the primary side of the transformer T1 is simultaneously connected with an output end of the step-down sub-circuit and pins 5, 6, 7 and 8 of a PWM controller U1, and a sampling sub-circuit is connected in parallel between a pin 4 and a pin 5 of the transformer T1. A power supply sub-circuit is connected in series between a pin 4 and a pin 5 of the transformer T1, a first filtering sub-circuit is connected in series between a pin 6 and a pin 7 of the transformer T1, and a second filtering sub-circuit is connected in series between a pin 9 and a pin 10 of the transformer T1. According to the utility model, the specific requirements of multiple devices are met, the circuit is simplified, the occupied space is reduced, and the manufacturing cost is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of power supply control technology, specifically relating to a flyback switching power supply control circuit. Background Technology

[0002] Flyback switching power supplies are widely used in AC / DC conversion, providing electrical isolation between input and output. A flyback switching power supply is controlled by pulse width modulation (PWM), which generates a high-frequency square wave signal on the primary side of a transformer by controlling the closing and turning of a MOSFET. The transformer transmits the generated square wave signal to the secondary side via magnetic field induction. Through the filtering and rectification of diodes and capacitors, a stable DC output is obtained at the output. A flyback switching power supply consists of a PWM controller, MOSFETs, a transformer, output rectifier diodes, output filter capacitors, and an output voltage sampling circuit. Traditional flyback switching power supply output voltage sampling circuits consist of optocouplers, voltage regulators, resistors, and capacitors, resulting in a complex circuit, higher cost, and larger PCB footprint. Furthermore, traditional control circuits require external MOSFETs, increasing space and cost. Utility Model Content

[0003] Purpose of this utility model: To provide a flyback switching power supply control circuit that solves the aforementioned problems existing in the prior art.

[0004] Technical solution: A flyback switching power supply control circuit includes a transformer T1 whose primary side pin 1 is connected to the input terminal of an external device; the primary side pin 1 of the transformer T1 is connected to the input terminal of a step-down sub-circuit; the primary side pin 3 of the transformer T1 is simultaneously connected to the output terminal of the step-down sub-circuit and pins 5, 6, 7, and 8 of a PWM controller U1; a sampling sub-circuit is connected in parallel between pins 4 and 5 of the transformer T1; a power supply circuit is connected in series between pins 4 and 5 of the transformer T1; a first filter sub-circuit is connected in series between pins 6 and 7 of the transformer T1; and a second filter sub-circuit is connected in series between pins 9 and 10 of the transformer T1.

[0005] Preferably, the step-down sub-circuit includes resistor R1, resistor R2, capacitor C1, and diode D1. One end of resistor R1 is connected to pin 1 of transformer T1 and one end of capacitor C1. The other end of resistor R1 is connected to the other end of capacitor C1 and one end of resistor R2. The other end of resistor R2 is connected to the negative terminal of diode D1. The positive terminal of diode D1 is connected to pin 3 of transformer T1.

[0006] Preferably, the sampling sub-circuit includes resistor R4, resistor R5, and capacitor C5. One end of resistor R4 is connected to pin 4 of transformer T1 and the input terminal of the power supply circuit. The other end of resistor R4 is connected to one end of capacitor R5, one end of capacitor C5, and pin 2 of PWM controller U1. The other end of resistor R5 is connected to the other end of capacitor C5, pin 3 of PWM controller U1, and the output terminal of the power supply circuit.

[0007] Preferably, the power supply circuit includes resistor R3, diode D2, and capacitor C2. One end of resistor R3 is connected to pin 4 of transformer T1, and the other end of resistor R3 is connected to the positive terminal of diode D2. The negative terminal of diode D2 is connected to both the positive terminal of capacitor C2 and pin 4 of PWM controller U1. The negative terminal of capacitor C2 is connected to pin 3 of PWM controller U1 and grounded.

[0008] Preferably, the first filter sub-circuit includes diode D4 and capacitor C4. The positive terminal of diode D4 is connected to pin 7 of transformer T1, the negative terminal of diode D4 is connected to the positive terminal of capacitor C4, and the negative terminal of capacitor C4 is connected to pin 6 of transformer T1.

[0009] Preferably, the second filter sub-circuit includes a diode D3 and a capacitor C3. The positive terminal of the diode D3 is connected to pin 10 of the transformer T1, the negative terminal of the diode D3 is connected to the positive terminal of the capacitor C3, and the negative terminal of the capacitor C3 is connected to pin 9 of the transformer T1.

[0010] Preferably, the transformer T1 is a TA24 / 4A model transformer.

[0011] Preferably, the PWM controller U1 is a PN6795D PWM controller.

[0012] Beneficial effects: This utility model relates to a flyback switching power supply control circuit. It uses the input terminal of the PWM controller to input DC voltage. After processing by the PWM controller, a high-frequency square wave is generated at both ends of the transformer T1. The transformer T1 transmits the generated square wave signal to the secondary winding of the transformer T1 through magnetic field induction. The two sets of outputs of the secondary winding of the transformer T1 are then sent to external devices to meet the specific needs of multiple devices. This not only simplifies the circuit but also reduces the space occupied and lowers the manufacturing cost. Attached Figure Description

[0013] Figure 1 This is the overall circuit diagram of this utility model. Detailed Implementation

[0014] like Figure 1As shown, this utility model provides a technical solution: a flyback switching power supply control circuit, including a transformer T1, a step-down sub-circuit, a sampling sub-circuit, a power supply circuit, a first filter sub-circuit, and a second filter sub-circuit. The transformer T1 is a TA24 / 4A model transformer. Pin 1 of the primary side of transformer T1 is connected to the input terminal of an external device. Pin 1 of the primary side of transformer T1 is also connected to the input terminal of the step-down sub-circuit, which reduces the higher input voltage to the required lower output voltage level. Pin 3 of the primary side of transformer T1 is simultaneously connected to the output terminal of the step-down sub-circuit and pins 5, 6, 7, and 8 of the PWM controller U1. A sampling sub-circuit is connected in parallel between pins 4 and 5 of transformer T1. The voltage signal output by transformer T1 is converted into a discrete signal by a sampling sub-circuit for processing and analysis by the PWM controller. The PWM controller U1 is a PN6795D model PWM controller. A power supply circuit is connected in series between pins 4 and 5 of transformer T1. The stable voltage output of the power supply circuit powers the PWM controller, ensuring stable operation. A first filter sub-circuit is connected in series between pins 6 and 7 of transformer T1, and a second filter sub-circuit is connected in series between pins 9 and 10 of transformer T1. This allows transformer T1 to form two sets of outputs, meeting the specific needs of multiple devices. This not only simplifies the circuit but also reduces space occupation and manufacturing costs.

[0015] In a further embodiment, the step-down sub-circuit includes resistors R1 and R2, capacitor C1, and diode D1. One end of resistor R1 is connected to pin 1 of transformer T1 and one end of capacitor C1. The other end of resistor R1 is connected to the other end of capacitor C1 and one end of resistor R2. The other end of resistor R2 is connected to the negative terminal of diode D1. The positive terminal of diode D1 is connected to pin 3 of transformer T1. The step-down sub-circuit reduces the high voltage input to the low voltage required by transformer T1, providing transformer T1 with a stable and reliable low voltage, ensuring that transformer T1 can operate normally.

[0016] In a further embodiment, the sampling sub-circuit includes resistors R4 and R5 and capacitor C5. One end of resistor R4 is connected to pin 4 of transformer T1 and the input terminal of the power supply circuit. The other end of resistor R4 is connected to one end of capacitor R5, one end of capacitor C5, and pin 2 of PWM controller U1. The other end of resistor R5 is connected to the other end of capacitor C5, pin 3 of PWM controller U1, and the output terminal of the power supply circuit. The PWM controller realizes the conversion of analog signals to digital signals, providing accurate data support for the digital system, reducing data transmission volume, and improving the real-time monitoring and control capabilities of the system.

[0017] In a further embodiment, the power supply circuit includes resistor R3, diode D2, and capacitor C2. One end of resistor R3 is connected to pin 4 of transformer T1, and the other end of resistor R3 is connected to the positive terminal of diode D2. The negative terminal of diode D2 is connected to both the positive terminal of capacitor C2 and pin 4 of PWM controller U1. The negative terminal of capacitor C2 is connected to pin 3 of PWM controller U1 and grounded. The power supply circuit provides a stable operating voltage to the PWM controller, ensuring stable operation of the PWM controller.

[0018] In a further embodiment, the first filter sub-circuit includes diode D4 and capacitor C4. The positive terminal of diode D4 is connected to pin 7 of transformer T1, and the negative terminal of diode D4 is connected to the positive terminal of capacitor C4. The negative terminal of capacitor C4 is connected to pin 6 of transformer T1. The second filter sub-circuit includes diode D3 and capacitor C3. The positive terminal of diode D3 is connected to pin 10 of transformer T1, and the negative terminal of diode D3 is connected to the positive terminal of capacitor C3. The negative terminal of capacitor C3 is connected to pin 9 of transformer T1. That is, with the cooperation of the first and second filter sub-circuits, two sets of outputs are formed to power different devices, reducing costs and PCB layout space.

[0019] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and all such equivalent transformations fall within the protection scope of the present invention.

Claims

1. A flyback switching power supply control circuit, characterized in that, The transformer T1 includes a primary side pin 1 connected to the input terminal of an external device, a primary side pin 1 of the transformer T1 connected to the input terminal of a step-down sub-circuit, a primary side pin 3 of the transformer T1 connected to both the output terminal of the step-down sub-circuit and pins 5, 6, 7, and 8 of the PWM controller U1, a sampling sub-circuit connected in parallel between pins 4 and 5 of the transformer T1, a power supply circuit connected in series between pins 4 and 5 of the transformer T1, a first filter sub-circuit connected in series between pins 6 and 7 of the transformer T1, and a second filter sub-circuit connected in series between pins 9 and 10 of the transformer T1.

2. The flyback switching power supply control circuit according to claim 1, characterized in that, The step-down sub-circuit includes resistor R1, resistor R2, capacitor C1, and diode D1. One end of resistor R1 is connected to pin 1 of transformer T1 and one end of capacitor C1. The other end of resistor R1 is connected to the other end of capacitor C1 and one end of resistor R2. The other end of resistor R2 is connected to the negative terminal of diode D1. The positive terminal of diode D1 is connected to pin 3 of transformer T1.

3. The flyback switching power supply control circuit according to claim 1, characterized in that, The sampling sub-circuit includes resistor R4, resistor R5, and capacitor C5. One end of resistor R4 is connected to pin 4 of transformer T1 and the input terminal of the power supply circuit. The other end of resistor R4 is connected to one end of capacitor R5, one end of capacitor C5, and pin 2 of PWM controller U1. The other end of resistor R5 is connected to the other end of capacitor C5, pin 3 of PWM controller U1, and the output terminal of the power supply circuit.

4. The flyback switching power supply control circuit according to claim 1, characterized in that, The circuit consists of resistor R3, diode D2, and capacitor C2. One end of resistor R3 is connected to pin 4 of transformer T1, and the other end of resistor R3 is connected to the positive terminal of diode D2. The negative terminal of diode D2 is connected to both the positive terminal of capacitor C2 and pin 4 of PWM controller U1. The negative terminal of capacitor C2 is connected to pin 3 of PWM controller U1 and grounded.

5. The flyback switching power supply control circuit according to claim 1, characterized in that, The first filter sub-circuit includes a diode D4 and a capacitor C4. The positive terminal of the diode D4 is connected to pin 7 of the transformer T1, the negative terminal of the diode D4 is connected to the positive terminal of the capacitor C4, and the negative terminal of the capacitor C4 is connected to pin 6 of the transformer T1.

6. The flyback switching power supply control circuit according to claim 1, characterized in that, The second filter sub-circuit includes a diode D3 and a capacitor C3. The positive terminal of the diode D3 is connected to pin 10 of the transformer T1, the negative terminal of the diode D3 is connected to the positive terminal of the capacitor C3, and the negative terminal of the capacitor C3 is connected to pin 9 of the transformer T1.

7. The flyback switching power supply control circuit according to claim 1, characterized in that, The transformer T1 is a TA24 / 4A model transformer.

8. The flyback switching power supply control circuit according to claim 1, characterized in that, The PWM controller U1 is a PN6795D model PWM controller.

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