A direct current detection and feedback circuit

Abstract

The utility model relates to a direct current detection and feedback circuit, its characterized in that: including auxiliary module F1, auxiliary module F1's third foot is connected with power input end, auxiliary module F1's second foot is connected with triode Q4's collector and resistance R2's one end respectively, auxiliary module F1's first foot is connected with triode Q4's emitter and resistance R1's one end respectively, triode Q4's base set is connected with resistance R1's other end common power output end, resistance R2's other end ground connection, the utility model can realize constant current - constant voltage output, by this increase the stability of circuit, and the required electronic device is simple, reduces cost and makes craft.

Description

Technical Field

[0001] This utility model relates to the field of electronic technology, and in particular to a DC current detection and feedback circuit. Background Technology

[0002] Currently available DC-DC constant current voltage converter integrated circuits, whether boost or buck, are all constant voltage output circuits. To achieve constant current output using a constant voltage integrated circuit, whether boosting or bucking, current detection is required to sense the current and then control the output voltage. However, the mainstream current detection methods on the market are diverse, involving numerous components, which actually increases the overall system cost and instability. Summary of the Invention

[0003] In view of the defects or deficiencies in the existing technology, the technical problem to be solved by this utility model is to provide a DC current detection and feedback circuit.

[0004] To achieve the above objectives, the present invention provides a DC current detection and feedback circuit, comprising an auxiliary module F1. The third pin of the auxiliary module F1 is connected to the power input terminal. The second pin of the auxiliary module F1 is connected to the collector of transistor Q4 and one end of resistor R2. The first pin of the auxiliary module F1 is connected to the emitter of transistor Q4 and one end of resistor R1. The base of transistor Q4 and the other end of resistor R1 are connected to the power output terminal. The other end of resistor R2 is grounded. The auxiliary module F1 includes a chip U1. The VIN pin of the chip U1 is connected to the power input terminal VIN via one end of the inductor L1 and one end of the capacitor C1. The other end of the capacitor C1 is grounded. The VIN pin of the chip U1 is connected to one end of the resistor R5. The other end of the resistor R5 is connected to the EN pin of the chip U1 and one end of the capacitor C3. The other end of the capacitor C3 is grounded via the GND pin of the chip U1. The SW pin of the chip U1 is connected to the positive terminal of the diode D1 and the other end of the inductor L1. The negative terminal of the diode D1 is connected to the power output terminal via one end of the resistor R3 and one end of the capacitor C2. The other end of the resistor R3 is connected to the FB pin of the chip U1 and one end of the resistor R2. The other end of the resistor R2 is grounded.

[0005] As a further improvement of this utility model, the auxiliary module F1 is a boost integrated circuit.

[0006] As a further improvement of this utility model, the integrated circuit chip of the auxiliary module F1 is model number BL8042.

[0007] As a further improvement of this utility model, the auxiliary module F1 is a step-down integrated circuit.

[0008] As a further improvement of this utility model, the integrated circuit chip of the auxiliary module F1 is model ME310X.

[0009] As a further improvement of this invention, the resistance of resistor R1 is 0.1Ω. As a further improvement of this invention, the resistance of resistor R2 is 1200Ω. As a further improvement of this utility model, the resistor R is 37800Ω.

[0010] The beneficial effects of this utility model are: In this invention, the input power supply flows through an auxiliary module F1 and a resistor R1 for current detection, while simultaneously creating a voltage difference across the resistor R1. The two ends of the resistor R1 are connected to the base and emitter of a transistor Q4, respectively. The collector of the transistor Q4 receives the feedback signal from the FB pin of the auxiliary module F1 to realize the amplification circuit, which can achieve constant current-constant voltage output, thereby increasing the stability of the circuit. Moreover, the required electronic components are simple, reducing costs and manufacturing processes. Attached Figure Description

[0011] Figure 1 This is the circuit schematic diagram provided by this utility model; Figure 2 This is the circuit schematic diagram of the auxiliary module F1 provided by this utility model. Detailed Implementation

[0012] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0013] like Figure 1 The diagram shows a DC current detection and feedback circuit according to this invention, including an auxiliary module F1. The third pin of the auxiliary module F1 is connected to the power input terminal, the second pin of the auxiliary module F1 is connected to the collector of transistor Q4 and one end of resistor R2, and the first pin of the auxiliary module F1 is connected to the emitter of transistor Q4 and one end of resistor R1. The base of transistor Q4 and the other end of resistor R1 are connected to the power output terminal. The other end of resistor R2 is grounded. like Figure 2As shown, auxiliary module F1 includes chip U1. The VIN pin of chip U1 is connected to the power input terminal VIN along with one end of inductor L1 and one end of capacitor C1. The other end of capacitor C1 is grounded. The VIN pin of chip U1 is connected to one end of resistor R5. The other end of resistor R5 is connected to the EN pin of chip U1 and one end of capacitor C3. The other end of capacitor C3 is grounded along with the GND pin of chip U1. The SW pin of chip U1 is connected to the positive terminal of diode D1 and the other end of inductor L1. The negative terminal of diode D1 is connected to the power output terminal along with one end of resistor R3 and one end of capacitor C2. The other end of resistor R3 is connected to the FB pin of chip U1 and one end of resistor R2. The other end of resistor R2 is grounded.

[0014] Preferably, in this invention, the auxiliary module F1 is a boost or buck integrated circuit; the chip U1 can be a buck ME310X series (Nanjing Weimeng), a boost BL8042 (Shanghai Belling), etc., but is not limited to those listed. They have a common characteristic: their output voltage can rise and fall continuously inversely proportional to the voltage at the feedback terminal (FB point).

[0015] Preferably, in this invention, R1 is a pure resistor that forms a current detection circuit.

[0016] Preferably, in this invention, R1 = 0.1Ω, R2 = 1200Ω, and R3 = 7800Ω.

[0017] The principle of this circuit is as follows: Capacitor C3 is an enable filter capacitor, connected between the EN pin of chip U1 and ground; resistor R2 is a sampling voltage divider resistor, connected between the FB pin of chip U1 and ground, and together with resistor R3, it divides the voltage to provide the sampling voltage. The process of DC current detection and feedback is as follows: the input power supply passes through auxiliary module F1, flows through the current detection resistor R1, and forms a voltage difference across the resistor. The resistance value of resistor R1 determines the constant current output current value; transistor Q4 is a germanium NPN transistor, which processes the current across the sampling resistor R1 and converts it into a voltage signal output, thus forming a current amplification circuit. Combined with the feedback circuit adjustment, this achieves the purpose of ensuring a stable output current.

[0018] According to the circuit diagram, the formula for calculating the output voltage is: Vout = Vfb * (r1 + r2) / r2; Where: Vfb is the internal reference voltage of chip U1; r1 and r2 are the resistance values ​​of resistors R1 and R2, respectively.

[0019] Ur=I*r1; Ur is the voltage drop across the current sensing resistor R1; I is the current in the circuit; r1 is the resistance value of resistor R1; Since the conduction voltage of the germanium NPN transistor is 0.3V, when Ur is greater than 0.3V, the transistor Q4 conducts, causing the voltage across resistor R2 (FB point) to rise, the output voltage of the functional module to drop, and the current in the path to decrease, thereby achieving the purpose of stabilizing the current. Stabilizing the current can also achieve voltage stabilization.

[0020] As stated above, the path current is I = 0.3 / R. The resistance value of the current sensing resistor can be changed according to different current requirements. For example, to achieve an output current of 3A, a voltage of 9V, and Vfb = 1.2V, but this is not limited to the examples listed.

[0021] In summary, in this invention, the input power supply flows through the auxiliary module F1 and the current is detected by the resistor R1. At the same time, a voltage difference is formed across the resistor R1. The two ends of the resistor R1 are connected to the base and emitter of the transistor Q4, respectively. The collector of the transistor Q4 receives the feedback signal from the FB pin of the auxiliary module F1 to realize the amplification circuit, which can achieve constant current-constant voltage output, thereby increasing the stability of the circuit. Moreover, the required electronic components are simple, reducing costs and manufacturing processes.

[0022] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the protection scope of the present invention.

Claims

1. A DC current detection and feedback circuit, characterized in that: The system includes an auxiliary module F1. The third pin of the auxiliary module F1 is connected to the power input terminal. The second pin of the auxiliary module F1 is connected to the collector of transistor Q4 and one end of resistor R2. The first pin of the auxiliary module F1 is connected to the emitter of transistor Q4 and one end of resistor R1. The base of transistor Q4 and the other end of resistor R1 are connected to the power output terminal. The other end of resistor R2 is grounded. The auxiliary module F1 includes a chip U1. The VIN pin of the chip U1 is connected to the power input terminal VIN via one end of the inductor L1 and one end of the capacitor C1. The other end of the capacitor C1 is grounded. The VIN pin of the chip U1 is connected to one end of the resistor R5. The other end of the resistor R5 is connected to the EN pin of the chip U1 and one end of the capacitor C3. The other end of the capacitor C3 is grounded via the GND pin of the chip U1. The SW pin of the chip U1 is connected to the positive terminal of the diode D1 and the other end of the inductor L1. The negative terminal of the diode D1 is connected to the power output terminal via one end of the resistor R3 and one end of the capacitor C2. The other end of the resistor R3 is connected to the FB pin of the chip U1 and one end of the resistor R2. The other end of the resistor R2 is grounded.

2. The DC current detection and feedback circuit according to claim 1, characterized in that: The auxiliary module F1 is a boost integrated circuit.

3. The DC current detection and feedback circuit according to claim 2, characterized in that: The integrated circuit chip of the auxiliary module F1 is model BL8042.

4. The DC current detection and feedback circuit according to claim 1, characterized in that: The auxiliary module F1 is a step-down integrated circuit.

5. The DC current detection and feedback circuit according to claim 4, characterized in that: The integrated circuit chip of the auxiliary module F1 is model ME310X.

6. The DC current detection and feedback circuit according to claim 1, characterized in that: The resistance of resistor R1 is 0.1Ω.

7. The DC current detection and feedback circuit according to claim 1, characterized in that: The resistance of resistor R2 is 1200Ω.

8. The DC current detection and feedback circuit according to claim 1, characterized in that: The resistor is R37800Ω.

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