Voltage detection circuit of switching power supply power supply control system

Abstract

The utility model particularly relates to a voltage detection circuit of a switching power supply control system, which comprises a bridge rectifier DB1 and a transformer T1, an output end of the bridge rectifier DB1 is connected onto the transformer T1, a primary coil end of the transformer T1 is led out to be connected with a fourth diode D4, the fourth diode D4 is connected with a fifth pin of a comparator IC2, and the fifth pin of the comparator IC2 is connected with a second pin of the comparator IC2. A mains supply is connected to a second pin of a comparator IC2 through a fifth diode D5, a first pin of the comparator IC2 is connected to a second pin of a third optical coupler IC3, a fourth pin of the third optical coupler IC3 is connected with a fourth pin of a detection chip MCU, the circuit carries out voltage sampling and reference voltage reading through the comparator IC2, the third optical coupler IC3 outputs square wave signals and feeds back the square wave signals to the detection chip MCU, and the detection chip MCU is connected with the detection chip MCU. And the commercial power voltage value is calculated according to a pulse width and sine wave calculation formula, so that the demand of detecting the commercial power voltage in a switching power supply system in reality is met.

Description

Technical Field

[0001] This utility model specifically relates to a voltage detection circuit for a switching power supply control system. Background Technology

[0002] Low-frequency transformer detection circuits determine the mains voltage by detecting the transformer's output voltage. However, low-frequency transformers suffer from drawbacks such as high standby power consumption, low conversion efficiency, and high material costs. With national standards increasing requirements for standby power consumption of electrical appliances, traditional low-frequency transformers no longer meet these requirements. Replacing low-frequency transformers with switching power supplies is an inevitable trend. Since control systems powered by switching power supplies cannot detect mains voltage like low-frequency transformers, the following detection circuit addresses the need for mains voltage detection in switching power supply systems. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a voltage detection circuit for a switching power supply control system, to address the need for detecting mains voltage in practical switching power supply systems.

[0004] According to the present invention, a voltage detection circuit for a switching power supply control system includes a rectifier bridge DB1 and a transformer T1. The output terminal of the rectifier bridge DB1 is connected to the transformer T1. The circuit is characterized in that: a fourth diode D4 is connected to the primary coil terminal of the transformer T1, the fourth diode D4 is connected to pin 5 of the comparator IC2, the mains power is connected to pin 2 of the comparator IC2 via a fifth diode D5, pin 1 of the comparator IC2 is connected to pin 2 of the third optocoupler IC3, pin 4 of the third optocoupler IC3 is connected to pin 4 of the detection chip MCU, and pin 3 of the transformer T1 is connected to the step-down chip IC1.

[0005] Specifically, the comparator IC2 supplies power to the third optocoupler IC3: the fourth diode D4 is connected to pin 5 of the transformer T1, the other end of the fourth diode D4 is connected to the third electrolytic capacitor E3 and the twenty-sixth resistor R26, and the other end of the twenty-sixth resistor R26 is connected to pin 5 of the comparator IC2.

[0006] Specifically, the sampling circuit of the comparator IC2 is as follows: a twentieth resistor R20 is connected to pin 2 of the comparator IC2, a nineteenth resistor R19 is connected to the twentieth resistor R20, the nineteenth resistor R19 is connected to the fifth diode D5, and the fifth diode D5 is connected to the input mains power.

[0007] Specifically, the common terminal between pin 2 of the comparator IC2 and the twentieth resistor R20 is connected to the negative terminal of the common power supply via a twenty-first resistor R21.

[0008] Specifically, the comparator IC2 reference voltage circuit has the following configuration: pin 3 of the comparator IC2 is connected to the 23rd resistor R23 and the 22nd resistor R22. The other end of the 23rd resistor R23 is connected to the negative terminal of the common power supply, and the other end of the 22nd resistor R22 is connected to pin 8 of the positive terminal of the comparator IC2 power supply.

[0009] Specifically, in the output circuit of the comparator IC2, a 24th resistor R24 ​​is connected between pin 1 of the comparator IC2 and pin 2 of the third optocoupler IC3.

[0010] Specifically, a 26th resistor R26, a third electrolytic capacitor E3, and a Zener diode DZ1 are respectively provided between the fourth diode D4 and pin 8 of the comparator IC2. The 26th resistor R26 and the Zener diode DZ1 are connected in series. One end of the third electrolytic capacitor E3 is connected to the common terminal between the fourth diode D4 and the 26th resistor R26, and the other end of the third electrolytic capacitor E3 is connected to the other end of the rectifier diode DZ1. Pin 8 of the comparator IC2 is connected to the common terminal between the 26th resistor R26 and the Zener diode DZ1.

[0011] Specifically, pin 4 of the third optocoupler IC3 is also connected to a 25th resistor R25, the other end of which is connected to the +VCC terminal. Pin 3 of the third optocoupler IC3 is connected to a fourth capacitor C4, and the common terminal between pin 3 of the third optocoupler IC3 and the fourth capacitor C4 is connected to the ground terminal GND.

[0012] The beneficial effects of this utility model are as follows: This circuit uses comparator IC2 to sample the voltage with the fifth diode D5 and read the reference voltage with the fourth diode D4. The third optocoupler IC3 on comparator IC2 outputs a square wave signal and feeds it back to the detection chip MCU. The detection chip MCU calculates the mains voltage value according to the pulse width and sine wave calculation formula, so as to solve the need for detecting the mains voltage in the actual switching power supply system. Attached Figure Description

[0013] The above and / or additional aspects and advantages of this invention will become apparent and readily understood in conjunction with the following description of the embodiments in conjunction with the accompanying drawings.

[0014] Figure 1 This is the circuit diagram of this utility model.

[0015] Figure 2 This is a schematic diagram of the detection chip MCU of this utility model.

[0016] Figure 3 This is a schematic diagram of the square wave output from the third optocoupler IC3. Detailed Implementation

[0017] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0018] The following is for reference. Figures 1 to 3 This invention describes a voltage detection circuit for a switching power supply control system according to an embodiment of the present invention. The circuit includes a rectifier bridge DB1 and a transformer T1. The output terminal of the rectifier bridge DB1 is connected to the transformer T1. A fourth diode D4 is connected to the primary winding terminal of the transformer T1. The fourth diode D4 is connected to pin 8 of comparator IC2. Diode D5 is connected in series with resistors R19 and R20 to pin 2 of comparator IC2. The voltage at pin 8 of comparator IC2 is connected in series with resistors R22 and R23. The common point of R22 and R23 is connected to pin 3 of comparator IC2. Pin 1 of comparator IC2 is connected to pin 2 of a third optocoupler IC3. Pin 4 of the third optocoupler IC3 is connected to pin 4 of the detection chip MCU. Pin 3 of transformer T1 is connected to a step-down chip IC1.

[0019] This circuit uses comparator IC2 connected to the fifth diode D5 for voltage sampling and the fourth diode D4 for reading the reference voltage. The third optocoupler IC3 on comparator IC2 outputs a square wave signal, which is fed back to the detection chip MCU. The MCU calculates the mains voltage value based on the pulse width and sine wave calculation formula, thus addressing the need for mains voltage detection in switching power supply systems. In this embodiment, the peak value of the pulse sine wave is 5V; the mains voltage detection range is 180VAC~265VAC.

[0020] The comparator IC2 is model LM393. Pin 2 of comparator IC2 is connected to the twentieth resistor R20. R20 is also connected to the nineteenth resistor R19. R19 is connected to a rectifier diode D5, which is connected to the AC input. The common terminal between pin 2 of comparator IC2 and the twentieth resistor R20 is connected to the twenty-first resistor R21. Pin 3 of comparator IC2 is connected to the midpoint between resistors R23 and R22. The other end of resistor R23 is connected to the common ground terminal of the power supply. The other end of resistor R22 is connected to pin 8 of comparator IC2 and pin 1 of the third optocoupler IC3. The twenty-fourth resistor R24 ​​is connected between pin 1 of comparator IC2 and pin 2 of the third optocoupler IC3. A 26th resistor R26, a third electrolytic capacitor E3, and a Zener diode DZ1 are connected between the fourth diode D4 and pin 8 of comparator IC2. The 26th resistor R26 and the Zener diode DZ1 are connected in series. The third electrolytic capacitor E3 acts as a filter, providing a cleaner DC current. The Zener diode DZ1 stabilizes the power supply to comparator IC2. One end of the third electrolytic capacitor E3 is connected to the common terminal between the fourth diode D4 and the 26th resistor R26, and the other end of the third electrolytic capacitor E3 is connected to the other end of the Zener diode DZ1. Pin 8 of comparator IC2 is connected to the common terminal between the 26th resistor R26 and the Zener diode DZ1. Pin 4 of the third optocoupler IC3 is also connected to a 25th resistor R25, the other end of which is connected to the VCC terminal. Pin 3 of the third optocoupler IC3 is connected to a fourth capacitor C4. The common terminal between pin 3 of the third optocoupler IC3 and the fourth capacitor C4 is connected to the ground terminal GND.

[0021] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A voltage detection circuit of a switching power supply control system, comprising a rectifier bridge stack DB1 and a transformer T1, the output of the rectifier bridge stack DB1 being connected to the transformer T1, characterized in that: The primary coil end of transformer T1 is connected with the fourth diode D4, the fourth diode D4 is connected with the pin 5 of comparator IC2, the commercial power is connected with the pin 2 of comparator IC2 through the fifth diode D5, the pin 1 of comparator IC2 is connected with the pin 2 of the third optocoupler IC3, the pin 4 of the third optocoupler IC3 is connected with the pin 4 of the detection chip MCU, the pin 3 of transformer T1 is connected with the voltage reduction chip IC1.

2. The voltage detection circuit of a switching power supply control system according to claim 1, wherein: The comparator IC2 supplies power to the third optocoupler IC3: the fourth diode D4 is connected with the pin 5 of transformer T1, the other end of the fourth diode D4 is connected with the third electrolytic capacitor E3 and the twenty-sixth resistor R26, the other end of the twenty-sixth resistor R26 is connected with the pin 5 of comparator IC2.

3. The voltage detection circuit of a switching power supply control system according to claim 1, wherein: The sampling circuit of comparator IC2: the pin 2 of comparator IC2 is connected with the twentieth resistor R20, the twentieth resistor R20 is also connected with the nineteenth resistor R19, the nineteenth resistor R19 is connected with the fifth diode D5, the fifth diode D5 is connected with the input commercial power.

4. The voltage detection circuit of a switching power supply control system according to claim 1, wherein: The common end between the pin 2 of comparator IC2 and the twentieth resistor R20 is connected with the twenty-first resistor R21 to the common power negative pole.

5. The voltage detection circuit of a switching power supply control system according to claim 1, wherein: The reference voltage circuit of comparator IC2: the pin 3 of comparator IC2 is connected with the twenty-third resistor R23 and the twenty-second resistor R22 respectively, the other end of the twenty-third resistor R23 is connected with the common power negative pole, the other end of the twenty-second resistor R22 is connected with the power positive pole pin 8 of comparator IC2.

6. The voltage detection circuit of a switching power supply control system according to claim 1, wherein: The output circuit of comparator IC2: the pin 1 of comparator IC2 is connected with the pin 2 of the third optocoupler IC3 through the twenty-fourth resistor R24.

7. The voltage detection circuit of a switching power supply control system according to claim 1, wherein: The fourth diode D4 and the pin 8 of comparator IC2 are respectively provided with the twenty-sixth resistor R26, the third electrolytic capacitor E3 and the voltage stabilizing diode DZ1, the twenty-sixth resistor R26 and the voltage stabilizing diode DZ1 are connected in series, one end of the third electrolytic capacitor E3 is connected with the common end between the fourth diode D4 and the twenty-sixth resistor R26, one end of the third electrolytic capacitor E3 is connected with the other end of the rectifier diode DZ1, the pin 8 of comparator IC2 is connected with the common end between the twenty-sixth resistor R26 and the voltage stabilizing diode DZ1.

8. The voltage detection circuit of a switching power supply control system according to claim 1, wherein: The pin 4 of the third optocoupler IC3 is also connected with the twenty-fifth resistor R25, the other end of the twenty-fifth resistor R25 is connected with the +VCC end, the pin 3 of the third optocoupler IC3 is connected with the fourth capacitor C4, the common end between the pin 3 of the third optocoupler IC3 and the fourth capacitor C4 is connected with the ground end GND.

Images