Circuit for adjusting magnitude of output voltage

Abstract

The utility model discloses a circuit for adjusting output voltage, which comprises a comparator circuit, a reference voltage circuit and a variable input circuit, and the comparator circuit outputs corresponding voltage according to comparison of input voltage of a reference input end and input voltage of a variable input end. The reference voltage circuit outputs fixed reference voltage and is connected to the reference input end of the comparator circuit; the variable input circuit outputs a variable voltage and is connected to the variable input end of the comparator circuit. The circuit has the advantages that the circuit is simple in structure, low in cost, stable, reliable and capable of achieving output of various voltages; output of different voltages can be realized only by increasing or decreasing the number of the adjusting resistors according to needs.

Description

Technical Field

[0001] The utility model relates to the technical field of switching power supplies, in particular to a circuit for adjusting the magnitude of an output voltage, and is especially applied to a switching power supply output control circuit. Background Art

[0002] With the continuous innovation of technology, the application prospects of transmitting power supplies are becoming more and more extensive, and it is an indispensable part of the rapid development of today's electronic information industry. Various electronic devices have different requirements for power supply voltage and current. Traditional power supply designs are all single fixed output voltage standards, resulting in various types of power supplies on the market. In order to meet the adjustable voltage output to adapt to a variety of environments and reduce design costs. For this situation, it is necessary to use a simple circuit design to adjust the output voltage, which can meet a variety of usage conditions, reduce the types of power supply models, facilitate unification, and reduce costs.

[0003] For example, an output voltage regulation circuit and power supply with patent application number 201510224744.6, although the regulation circuit disclosed in the patent can stably output the regulated voltage, it still has defects such as complex circuit structure and low cost, and cannot meet the purpose of simply realizing multiple voltage regulation outputs of the circuit. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a circuit for adjusting the output voltage, which can achieve adjustable output voltage and simple adjustment through a simple circuit.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a circuit for adjusting the output voltage, including a comparator circuit, a reference voltage circuit, and a variable input circuit, wherein the comparator circuit outputs a corresponding voltage according to the input voltages of the reference input terminal and the variable input terminal; the reference voltage circuit outputs a fixed reference voltage, which is connected to the reference input terminal of the comparator circuit; the variable input circuit outputs a variable voltage, which is connected to the variable input terminal of the comparator circuit.

[0006] The variable input circuit includes a plurality of resistors connected in series in sequence to form a resistor string, wherein the plurality of resistors include one or more adjustment resistors, one end of the resistor string is connected to a power supply V0, and the other end is grounded; a terminal is drawn between two of the series resistors in the resistor string as an output end of the variable input circuit, which is used to be connected to a variable input end of a comparator circuit; and an output voltage of the output end of the variable input circuit is adjusted by one or more adjustment resistors.

[0007] An electronic switch is connected in parallel at both ends of each adjusting resistor, and the output voltage at the output end of the variable input circuit is adjusted by controlling the short circuit of the electronic switch.

[0008] The electronic switch is an optocoupler, and two terminals on the output side of the optocoupler are respectively connected to two ends of the regulating resistor; one end of the two terminals on the input side of the optocoupler is connected to the power supply VCC, and the other end is grounded through a switch.

[0009] The comparator circuit includes a comparator N1B, the output end of the comparator N1B outputs a voltage after passing through a resistor R18; the output end of the comparator N1B is connected to its variable input end through a capacitor C11; a resistor R10 and a capacitor C14 are connected in series and then in parallel to both ends of the capacitor C11.

[0010] The reference voltage circuit includes a reference power supply Vef, which is connected to a reference input terminal of a comparator circuit, and the reference input terminal of the comparator circuit is grounded via a capacitor C21.

[0011] A resistor R16 is connected in series between the variable input terminal of the comparator circuit and the variable input circuit, and a resistor R12 is connected in series with a capacitor C13 and then connected in parallel across the resistor R16.

[0012] The multiple resistors include two adjusting resistors, and four voltages are input to the variable input terminal through the two adjusting resistors. The comparator circuit outputs four output voltages according to the four voltages at the variable input terminal.

[0013] The advantages of the present invention are: simple circuit structure, low cost, stable and reliable, and can realize the output of multiple voltages; different voltage outputs can be realized by simply increasing or decreasing the number of adjusting resistors according to needs. When there are n adjusting resistors, 2 n The output regulation of various voltages can meet the use requirements and the circuit is simpler, which is suitable for various fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following is a brief description of the contents expressed in the drawings of the present invention and the symbols in the drawings:

[0015] Figure 1 This is a schematic diagram of the circuit implementation under four output voltages in the utility model. DETAILED DESCRIPTION

[0016] The specific implementation of the present invention will be further explained in detail below by describing the optimal embodiment with reference to the accompanying drawings.

[0017] The utility model provides a circuit for adjusting the output voltage. After being connected to the internal control circuit, the conduction mode of the optocoupler is controlled by the on-off signal of the external hardware switch to change the voltage of the 6th pin of the comparator N1 B, thereby changing the output voltage. Different voltages are sent to the pin of the comparator N1 B to compare with the reference voltage to output different voltages. The specific scheme is as follows:

[0018] A circuit for adjusting the output voltage includes a comparator circuit, a reference voltage circuit, and a variable input circuit. The comparator circuit outputs a corresponding voltage according to the input voltages of the reference input terminal and the variable input terminal; the reference voltage circuit outputs a fixed reference voltage, which is connected to the reference input terminal of the comparator circuit; and the variable input circuit outputs a variable voltage, which is connected to the variable input terminal of the comparator circuit.

[0019] The variable input circuit includes a plurality of resistors connected in series in sequence to form a resistor string, wherein the plurality of resistors include one or more adjustment resistors, one end of the resistor string is connected to a power supply V0, and the other end is grounded; a terminal is drawn between two of the series resistors in the resistor string as an output end of the variable input circuit, which is used to be connected to a variable input end of a comparator circuit; and an output voltage of the output end of the variable input circuit is adjusted by one or more adjustment resistors.

[0020] An electronic switch is connected in parallel at both ends of each adjusting resistor, and the output voltage at the output end of the variable input circuit is adjusted by controlling the short circuit of the electronic switch. The electronic switch is an optical coupler, and the two terminals on the output side of the optical coupler are respectively connected to the two ends of the adjusting resistor; one end of the two terminals on the input side of the optical coupler is connected to the power supply VCC, and the other end is grounded through the switch.

[0021] The comparator circuit includes a comparator N1 B, the output end of the comparator N1 B outputs a voltage after passing through a resistor R18; the output end of the comparator N1 B is connected to its variable input end through a capacitor C11; a resistor R10 is connected in series with a capacitor C14 and then connected in parallel to both ends of the capacitor C11. The reference voltage circuit includes a reference power supply Vef, the reference power supply Vef is connected to the reference input end of the comparator circuit, and the reference input end of the comparator circuit is grounded through a capacitor C21. A resistor R16 is connected in series between the variable input end of the comparator circuit and the variable input circuit, and a resistor R12 is connected in series with a capacitor C13 and then connected in parallel to both ends of the resistor R16.

[0022] The working principle of the above circuit is that a reference voltage is input into one of the two input terminals of the comparator, and the reference voltage is fixed, and an adjustable voltage is input into the other input terminal. These two voltages are input into the two input terminals of the comparator, and the comparator outputs different voltage values ​​according to the comparison results of the two input terminal voltages. Therefore, different voltage outputs can be achieved by adjusting and controlling the input terminal voltage of the comparator.

[0023] like Figure 1 As shown, taking the on-off signal of two external control switches of the switching power supply as an example, four different output voltage values ​​can be adjusted. The circuit structure is as follows:

[0024] Resistors R5, R22, R15, R21, R44, and R26 are connected in series to form a resistor string, wherein one end of resistor R5 is connected to power supply V0, and one end of R26 of the battery string is connected to power supply ground GND. Resistors R22 and R44 are adjustment resistors, and both ends of resistor R22 are respectively connected to the two terminals on the output side of optocoupler V2; both ends of resistor R44 are respectively connected to the two output terminals on the output side of optocoupler V3; wherein power supply VCC is connected to the first terminal on the control side of optocoupler V2 via resistor R108, and the second terminal Vad-11 on the control side of V2 is grounded via an electric control switch; similarly, power supply VCC is connected to the first terminal on the control side of optocoupler V3 via resistor R109, and the second terminal Vad-12 on the control side of V3 is grounded via an electric control switch; the conduction of optocouplers V1 and V2 can be controlled respectively via the electric control switch. The lead-out terminal in the series circuit between resistors R21 and R12 is connected to the adjustable input terminal pin 6 of comparator N1 B through resistors R17 and R16 in sequence; the lead-out terminal in the series circuit between resistors R21 and R12 is connected to the power supply V0 through capacitor C18 and resistor R6 in sequence; the lead-out terminal in the series circuit between resistors R21 and R12 is connected to ground GND through capacitor C22. Capacitor C13 and resistor R12 are connected in series and then connected in parallel at both ends of resistor R16; the reference power supply is 5V power supply Vef-5V, which is directly connected to the reference input terminal pin 5 of comparator N1B; pin 5 is grounded through pad C21. Pin 6 of comparator N1B is connected to its output terminal pin 11 through capacitor C11, and resistor R10 and capacitor C14 are connected in series and then connected in parallel at both ends of C11. The output terminal pin 7 of the comparator N1B is connected to the ground GND after being connected in series with R18 and R23, and a terminal is drawn out between the resistors R18 and R23 as a voltage output terminal for outputting the regulated voltage.

[0025] The principle of adjustable output voltage is as follows: this circuit can provide four different output voltage values, and the output voltage can be changed by controlling the conduction mode of optocouplers V2 and V3. Vad-1 and Vad-1 2 are respectively connected to external control switches to control the conduction of optocouplers V2 and V3.

[0026] When the external switches of Vad-1 and Vad-12 are both in the closed position, the optocouplers V2 and V3 are both in the on state, the resistors R22 and R44 are short-circuited, and the voltage at the 6th pin of N1B is compared with the voltage at the 5th pin to output a voltage signal corresponding to the first voltage value.

[0027] When the Vad-1 connection switch is in the open state and the Vad-1 2 connection switch is in the closed state, the optocoupler V2 will be cut off, V3 will be turned on, and the resistor R22 will be connected to the circuit. After voltage division, the voltage at pin 6 of N1B will decrease, and the comparator will output a voltage signal corresponding to the second voltage value.

[0028] When the Vad-l2 connection switch is in the open state and the Vad-l ​​1 connection switch is in the closed state, the optocoupler V3 will be cut off, V2 will be turned on, and the resistor R44 will be connected to the circuit. After voltage division, the voltage at pin 6 of N1B will increase, and the comparator will output a voltage signal corresponding to the third voltage value.

[0029] When the external switches of Vad-1 and Vad-12 are both in the off position, and the optocouplers V2 and V3 are both in the off state, the resistors R22 and R44 are connected to the circuit, and the voltage at the 6th pin of N1B is compared with the voltage at the 5th pin to output a voltage signal, which corresponds to the fourth voltage value.

[0030] In the above, the on-off mode of the external switches Vad-l ​​1 and Vad-l2 is used to control the on-off and off-off of the optocouplers V2 and V3. The four different on-off and off modes are used to obtain the required four different output voltages, which reduces the operation process and is simple and convenient.

[0031] Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, they are all within the protection scope of the present invention.

Claims

1. A circuit for adjusting output voltage, characterized in that: It includes a comparator circuit, a reference voltage circuit, and a variable input circuit. The comparator circuit outputs a corresponding voltage according to the input voltages of the reference input terminal and the variable input terminal; the reference voltage circuit outputs a fixed reference voltage, which is connected to the reference input terminal of the comparator circuit; the variable input circuit outputs a variable voltage, which is connected to the variable input terminal of the comparator circuit.

2. A circuit for adjusting output voltage as claimed in claim 1, characterized in that: The variable input circuit includes a plurality of resistors connected in series in sequence to form a resistor string, wherein the plurality of resistors include one or more adjustment resistors, one end of the resistor string is connected to a power supply V0, and the other end is grounded; a terminal is drawn between two of the series resistors in the resistor string as an output end of the variable input circuit, which is used to be connected to a variable input end of a comparator circuit; and an output voltage of the output end of the variable input circuit is adjusted by one or more adjustment resistors.

3. A circuit for adjusting output voltage as claimed in claim 2, characterized in that: An electronic switch is connected in parallel at both ends of each adjusting resistor, and the output voltage at the output end of the variable input circuit is adjusted by controlling the short circuit of the electronic switch.

4. A circuit for adjusting output voltage as claimed in claim 3, characterized in that: The electronic switch is an optocoupler, and two terminals on the output side of the optocoupler are respectively connected to two ends of the regulating resistor; one end of the two terminals on the input side of the optocoupler is connected to the power supply VCC, and the other end is grounded through a switch.

5. A circuit for adjusting output voltage as claimed in claim 1, characterized in that: The comparator circuit includes a comparator N1 B, the output end of the comparator N1 B outputs a voltage after passing through a resistor R18; the output end of the comparator N1 B is connected to its variable input end through a capacitor C11; a resistor R10 and a capacitor C14 are connected in series and then in parallel to both ends of the capacitor C11.

6. A circuit for adjusting output voltage as claimed in any one of claims 1 to 5, characterized in that: The reference voltage circuit includes a reference power supply Vef, which is connected to a reference input terminal of a comparator circuit, and the reference input terminal of the comparator circuit is grounded via a capacitor C21.

7. A circuit for adjusting output voltage as claimed in any one of claims 1 to 5, characterized in that: A resistor R16 is connected in series between the variable input terminal of the comparator circuit and the variable input circuit, and a resistor R12 is connected in series with a capacitor C13 and then connected in parallel across the resistor R16.

8. A circuit for adjusting output voltage as claimed in any one of claims 2 to 5, characterized in that: The multiple resistors include two adjusting resistors, and four voltages are input to the variable input terminal through the two adjusting resistors. The comparator circuit outputs four output voltages according to the four voltages at the variable input terminal.

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