Constant current output circuit

Abstract

The utility model discloses a constant current output circuit, the constant current output circuit comprises a shunt voltage stabilizer and a triode, the shunt voltage stabilizer is connected in parallel to a power supply input, the base electrode of the triode is connected with the cathode of the shunt voltage stabilizer, the emitter electrode of the triode is connected with the reference end of the shunt voltage stabilizer, and the reference end of the shunt voltage stabilizer is connected with the triode. The collector electrode of the triode is used for being connected with a load, and the reference end of the shunt voltage stabilizer is connected with a sampling resistor so as to feed back the voltage output by the load. A sampling resistor is arranged as feedback, and a parallel voltage stabilizer is arranged to control output, so that current constant output of a load is achieved. The circuit is optimized in structure, and can be conveniently applied to a constant-current charging circuit and a load constant output circuit.

Description

Technical Field

[0001] The present application generally relates to the technical field of low-voltage electrical appliances, and in particular to a constant current output circuit. Background Art

[0002] A constant current output circuit is an electronic circuit whose primary function is to generate a constant current output, maintaining the current stability even when external conditions such as voltage or load resistance change. This circuit has applications in a variety of fields, including electronic measurement, electronic equipment, and power supply. The generation of a constant current source generally consists of a power supply, a constant current source, and a load. Constant current sources, which are composed of voltage regulators and transistors, have the advantage of a simple structure. However, when applied to constant current charging circuits, obtaining a structurally optimized circuit remains a challenge for researchers and developers. Utility Model Content

[0003] A main purpose of the present application is to provide a constant current output circuit, which obtains a structurally optimized constant current output circuit by setting a connection structure of a parallel regulator and a transistor, thereby overcoming one or more problems caused by the limitations and defects of the relevant technology at least to a certain extent.

[0004] To achieve the above application objectives, this application adopts the following technical solutions:

[0005] According to one aspect of the present application, a constant current output circuit is provided, which includes a parallel regulator and a transistor, the parallel regulator is connected in parallel to the power input, the base of the transistor is connected to the cathode of the parallel regulator, the emitter of the transistor is connected to the reference end of the parallel regulator, the collector of the transistor is used to connect to a load, and the reference end of the parallel regulator is connected to a sampling resistor to feedback the voltage output by the load.

[0006] According to one embodiment of the present application, the constant current output circuit includes a bias resistor, one end of the bias resistor is connected to the positive electrode of the power input, and the other end of the bias resistor is connected to the cathode of the parallel regulator and the base of the transistor.

[0007] According to one embodiment of the present application, the resistance of the bias resistor is set to 1K ohm.

[0008] According to an embodiment of the present application, one end of the sampling resistor is connected to the reference end of the shunt regulator, and the other end of the sampling resistor is connected to the anode of the shunt regulator.

[0009] According to an embodiment of the present application, the resistance of the sampling resistor is set to 2 ohms.

[0010] According to an embodiment of the present application, the shunt regulator is selected to be TL431, and the reference voltage of the reference terminal of the shunt regulator is set to 2.5V.

[0011] In this application, a sampling resistor is set as feedback and a parallel regulator is set to control the output, thereby achieving a constant current output of the load. With an optimized structure, it is easy to apply to constant current charging circuits and load constant output circuits.

[0012] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and other features and advantages of the present application will become more apparent by describing in detail example embodiments thereof with reference to the accompanying drawings.

[0014] Figure 1 is a schematic diagram of a constant current output circuit according to an exemplary embodiment. DETAILED DESCRIPTION

[0015] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent like or similar structures, and thus their detailed description will be omitted.

[0016] See also Figure 1 In one embodiment, the constant current output circuit includes a parallel regulator Q4 and a transistor Q3. The parallel regulator Q4 is connected in parallel to the power input, the base of the transistor Q3 is connected to the cathode of the parallel regulator Q4, the emitter of the transistor Q3 is connected to the reference end of the parallel regulator Q4, and the collector of the transistor Q3 is used to connect to the load. The reference end of the parallel regulator Q4 is connected to a sampling resistor R2 to feedback the voltage output by the load.

[0017] In this circuit, during normal operation, transistor Q3 conducts, the load operates, and further load current flows through sampling resistor R2, generating a corresponding voltage. When the voltage across sampling resistor R2 reaches the reference voltage of shunt regulator Q4, shunt regulator Q4 conducts, and transistor Q3 turns off, ceasing output to the load. At this point, sampling resistor R2 reports that no current is flowing, and no voltage is generated across it. Shunt regulator Q4 then turns off, and transistor Q3 conducts, resuming output to the load. This cycle repeats until the load current eventually stabilizes at a constant output value.

[0018] In a specific embodiment, the power input includes a positive electrode VIN+ and a negative electrode VIN−. The positive electrode VIN+ and the collector of the transistor Q3 are connected to the load outputs VOUT+ and VOUT−, respectively.

[0019] In a specific embodiment, the constant current output circuit includes a bias resistor R1, one end of which is connected to the positive electrode VIN+ of the power input, and the other end of which is connected to the cathode of the shunt regulator Q4 and the base of the transistor Q3. The bias resistor R1 can provide bias current for the transistor Q3 and the shunt regulator Q4, which is conducive to more stable operation of the circuit. Preferably, the resistance of the bias resistor R1 is set to 1K ohm.

[0020] In a specific embodiment, the shunt regulator Q4 is a TL431, and the reference voltage at the reference terminal of the shunt regulator is set to 2.5V, resulting in an output current of 1.25A. One end of the sampling resistor R2 is connected to the reference terminal of the shunt regulator Q4, and the other end of the sampling resistor R2 is connected to the anode of the shunt regulator Q4. Preferably, the resistance of the sampling resistor R2 is set to 2 ohms. Of course, it is understood that the output current can be adjusted by varying the resistance of the sampling resistor R2 within a certain range.

[0021] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A constant current output circuit, characterized in that: The constant current output circuit includes a parallel regulator and a triode, the parallel regulator is connected in parallel to the power input, the base of the triode is connected to the cathode of the parallel regulator, the emitter of the triode is connected to the reference end of the parallel regulator, the collector of the triode is used to connect to the load, and the reference end of the parallel regulator is connected to a sampling resistor to feed back the voltage output by the load.

2. The constant current output circuit according to claim 1, wherein: The constant current output circuit includes a bias resistor, one end of which is connected to the positive electrode of the power input, and the other end of which is connected to the cathode of the shunt regulator and the base of the transistor.

3. The constant current output circuit according to claim 2, wherein: The resistance of the bias resistor is set to 1K ohm.

4. The constant current output circuit according to claim 1, wherein: One end of the sampling resistor is connected to the reference end of the shunt regulator, and the other end of the sampling resistor is connected to the anode of the shunt regulator.

5. The constant current output circuit according to claim 4, wherein: The resistance of the sampling resistor is set to 2 ohms.

6. The constant current output circuit according to claim 1, wherein: The shunt regulator is TL431, and the reference voltage of the reference terminal of the shunt regulator is set to 2.5V.

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