CN204392087U - A kind of voltage stabilizing circuit - Google Patents

Abstract

This application discloses a kind of voltage stabilizing circuit, comprise DC power supply, first switching tube, second switch pipe, pull-up resistor, first feedback resistance and the second feedback resistance, by the corrective action of second switch pipe to the first switching tube, make the voltage stabilization of the second feedback resistance at an occurrence, simultaneously because the first feedback resistance and total resistance of the second feedback resistance and the difference of voltage stabilizing circuit load resistance resistance exceed preset resistive value, therefore less by the electric current on the first feedback resistance and the second feedback resistance, negligible compared with load current, this also makes by the electric current on the first feedback resistance and the second feedback resistance less by the impact of load current, voltage on second feedback resistance is highly stable, thus output voltage is highly stable.

Description

a voltage stabilizing circuit

technical field

The utility model relates to the technical field of voltage stabilization, in particular to a voltage stabilization circuit.

Background technique

A voltage stabilizing circuit is a circuit that can keep the output voltage constant when the input voltage, load, ambient temperature, circuit parameters, etc. change. The voltage stabilizing circuit can provide a stable DC power supply and is widely used in various electronic devices.

Referring to FIG. 1 , a circuit diagram of a voltage stabilizing circuit provided in the prior art, a resistor R and a voltage stabilizing diode D are connected in series between a DC power supply VB and a ground terminal, and the voltage across the voltage stabilizing diode D is the output voltage Vout. Since the Zener diode D reversely breaks down, within a certain current range (or within a certain power loss range), the terminal voltage is almost unchanged, that is, it shows a voltage stabilizing characteristic. Therefore, the output voltage Vout can be guaranteed. stability.

However, when the output load changes, the load current also changes accordingly, resulting in a change in the voltage regulation value of the Zener diode. Therefore, the voltage regulation accuracy of the existing voltage stabilization circuit is low.

Utility model content

In view of this, the utility model provides a voltage stabilizing circuit to improve the accuracy of voltage stabilizing.

A voltage stabilizing circuit, comprising: a DC power supply, a first switch tube, a second switch tube, a pull-up resistor, a first feedback resistor, and a second feedback resistor, wherein the first feedback resistor and the second feedback resistor The difference between the total resistance value of the voltage regulator circuit and the load resistance value exceeds the preset resistance value;

The input terminal of the first switch tube is connected to the DC power supply, the output terminal of the first switch tube is connected to the ground terminal through the first feedback resistor and the second feedback resistor connected in series, and the first switch tube The terminal voltage of the output terminal of the tube and the common terminal of the first feedback resistor is used as the output voltage of the voltage stabilizing circuit;

The input terminal of the second switch tube is connected to the control terminal of the first switch tube, the output terminal of the second switch tube is connected to the ground terminal, and the control terminal of the second switch tube is connected to the first feedback resistor and the common end of the second feedback resistor;

One end of the pull-up resistor is connected to the DC power supply, and the other end is connected to the control end of the first switch tube.

Preferably, it also includes: a voltage stabilizing capacitor;

The positive plate of the voltage stabilizing capacitor is connected to the common terminal of the first switch tube and the first feedback resistor, and the negative plate is connected to the ground terminal.

Preferably, it also includes: a thermistor;

One end of the thermistor is connected to the common end of the second switch tube and the first feedback resistor, and the other end of the thermistor is connected to a ground terminal through the second feedback resistor.

Preferably, the thermistor is a negative temperature coefficient thermistor.

Preferably, the first switch transistor is an NPN transistor.

Preferably, the first switch transistor is an NMOS transistor.

Preferably, the second switch transistor is an NPN transistor.

Preferably, the second switch transistor is an NMOS transistor.

It can be seen from the above technical solution that the utility model provides a voltage stabilizing circuit, including a DC power supply, a first switching tube, a second switching tube, a pull-up resistor, a first feedback resistor and a second feedback resistor. When the voltage on the second feedback resistor exceeds the turn-on voltage of the control terminal of the second switch tube, the second switch tube is turned on, and the voltage of the control terminal of the first switch tube is pulled down, and the first switch tube is turned off. At this time, the output voltage decreases, and the second switch tube The voltage on the feedback resistor decreases, the second switch tube is turned off, the voltage of the control terminal of the first switch tube rises, and the first switch tube is turned on again, and so on, and finally the voltage on the second feedback resistor is stabilized under the control of the second switch tube. Terminal open voltage. It can be seen that the adjustment effect of the second switch tube on the first switch tube stabilizes the voltage of the second feedback resistor at a specific value, and at the same time due to the total resistance of the first feedback resistor and the second feedback resistor and the load of the voltage stabilizing circuit The difference between the resistor resistance exceeds the preset resistance value, so the current passing through the first feedback resistor and the second feedback resistor is small, which is negligible compared with the load current, which also makes the current through the first feedback resistor and the second feedback resistor The current on the resistor is less affected by the load current, and the voltage on the second feedback resistor is very stable, so the output voltage is very stable. Compared with the prior art, the application greatly improves the voltage stabilization accuracy of the voltage stabilization circuit.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description It is only an embodiment of the utility model, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

Fig. 1 is a circuit diagram of a voltage stabilizing circuit disclosed in the prior art;

Fig. 2 is a circuit diagram of a voltage stabilizing circuit disclosed in an embodiment of the present invention;

Fig. 3 is a circuit diagram of another voltage stabilizing circuit disclosed in the embodiment of the present invention;

Fig. 4 is a circuit diagram of another voltage stabilizing circuit disclosed in the embodiment of the present invention;

Fig. 5 is a circuit diagram of another voltage stabilizing circuit disclosed by the embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. example. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

The embodiment of the utility model discloses a voltage stabilizing circuit to realize the improvement of voltage stabilizing precision.

Referring to Fig. 2 , a circuit diagram of a voltage stabilizing circuit disclosed in an embodiment of the present invention, the voltage stabilizing circuit includes: a DC power supply VB, a first switching tube Q1, a second switching tube Q2, a pull-up resistor R3, a first feedback resistor R1 and the second feedback resistor R2, the difference between the total resistance of the first feedback resistor R1 and the second feedback resistor R2 and the load resistance of the voltage stabilizing circuit exceeds a preset resistance;

in,

The input terminal of the first switching tube Q1 is connected to the DC power supply VB, the first feedback resistor R1 and the second feedback resistor R2 connected in series of the first switching tube Q1 are connected to the ground terminal, and the output terminal of the first switching tube Q1 is connected to the first feedback resistor R2. The terminal voltage of the common terminal of the resistor R1 is used as the output voltage Vout of the voltage stabilizing circuit;

The input terminal of the second switch tube Q2 is connected to the control terminal of the first switch tube Q1, the output terminal of the second switch tube Q2 is connected to the ground terminal, and the control terminal of the second switch tube Q2 is connected to the first feedback resistor R1 and the second feedback resistor R2 public end;

One end of the pull-up resistor R3 is connected to the DC power supply VB, and the other end is connected to the control end of the first switching tube Q1.

The pull-up resistor R3 is used to turn on the first switch tube Q1, and the specific resistance value depends on actual needs.

It should be noted that since the total resistance of the first feedback resistor R1 and the second feedback resistor R2 is connected in parallel with the load resistor of the voltage stabilizing circuit, in order to ensure the stability of the voltage on the second feedback resistor R2, the preset resistance needs to be It is ensured that the currents of the first feedback resistor R1 and the second feedback resistor R2 are relatively small and can be ignored compared with the load current. The specific value of the preset resistance depends on actual needs, and the present invention does not make a limitation here.

The working principle of the voltage regulator circuit is as follows:

The output voltage Vout is divided by the first feedback resistor R1 and the second feedback resistor R2, and the second switch tube Q2 collects the voltage on the second feedback resistor R2. When the voltage on the second feedback resistor R2 exceeds the control voltage of the second switch tube Q2 When the voltage at the terminal is turned on, the second switch tube Q2 is turned on, and the control terminal voltage of the first switch tube Q1 is pulled down, and the first switch tube Q1 is turned off. The current of the current path formed by the control terminal and output terminal of the tube Q1, the first feedback resistor R1 and the second feedback resistor R2 decreases, the output voltage Vout decreases, the voltage on the second feedback resistor R2 decreases, and the second switch tube Q2 is turned off. , the voltage at the control terminal of the first switching tube Q1 rises, and the first switching tube Q1 is turned on again. Repeatedly, finally, the voltage on the second feedback resistor R2 is stabilized at the turn-on voltage Vbeo of the control terminal of the second switching transistor Q2.

Since the voltage on the second feedback resistor R2 is generated by dividing the output voltage Vout through the first feedback resistor R1 and the second feedback resistor R2, therefore, Vbeo=Vout/(R1+R2)×R2, so the output voltage Vout is stable The value is: Vout=Vbeo×(R1+R2)/R2, since the control terminal turn-on voltage Vbeo of the second switch tube Q2, the first feedback resistor R1 and the second feedback resistor R2 are all fixed values, the stable The voltage circuit achieves voltage stabilization.

It should be noted that, by matching different voltage division values of the first feedback resistor R1 and the second feedback resistor R2 , the output voltage Vout can output different voltage values.

In summary, it can be seen that the adjustment effect of the second switch tube Q2 on the first switch tube Q1 makes the voltage of the second feedback resistor R2 stable at a specific value, and at the same time, due to the total of the first feedback resistor R1 and the second feedback resistor R2 The difference between the resistance value and the load resistance value of the voltage stabilizing circuit exceeds the preset resistance value, so the current passing through the first feedback resistor R1 and the second feedback resistor R2 is small, which is negligible compared with the load current, which also makes The current passing through the first feedback resistor R1 and the second feedback resistor R2 is less affected by the load current, and the voltage on the second feedback resistor R2 is very stable, so that the output voltage is very stable. Compared with the prior art, the present application The voltage stabilization accuracy of the voltage stabilization circuit is greatly improved.

Moreover, since the electrical components used in the voltage stabilizing circuit provided by the present application are all discrete components, the voltage stabilizing circuit provided in the present application has the advantages of easy implementation, low price and wide application range.

In order to further optimize the above embodiment, refer to FIG. 2 , which is a circuit diagram of a voltage stabilizing circuit disclosed in another embodiment of the present invention. On the basis of the embodiment shown in FIG. 1 , it also includes: a voltage stabilizing capacitor C1;

The positive plate of the voltage stabilizing capacitor C1 is connected to the common terminal of the first switching transistor Q1 and the first feedback resistor R1, and the negative plate is connected to the ground terminal.

When the output load changes, it takes a certain amount of time to adjust the voltage stabilizing circuit. At this time, the voltage stabilizing capacitor C1 plays the role of stabilizing the voltage.

In order to better realize the stability of the voltage stabilizing circuit, on the basis of the above embodiments, it also includes: a thermistor Rt;

One end of the thermistor Rt is connected to the common end of the second switch tube Q2 and the first feedback resistor R1, and the other end of the thermistor Rt is connected to the ground terminal through the second feedback resistor R2.

When the ambient temperature of the voltage stabilizing circuit changes, the turn-on voltage Vbeo of the control terminal of the second switch tube Q2 changes with the change of temperature, thus causing the output voltage Vout to shift, and a thermistor is connected in series with the second feedback resistor R2 After Rt, the thermistor Rt also changes with the change of temperature, thereby offsetting the change of the turn-on voltage Vbeo of the control terminal of the second switch tube Q2 caused by the temperature change, ensuring that the regulated voltage remains stable under different ambient temperatures. The stability of the output voltage Vout can be guaranteed.

Since the turn-on voltage Vbeo of the control terminal of the second switch tube Q2 decreases with the increase of temperature, it can be obtained from the formula Vout=Vbeo×(R1+R2)/R2 that in order to ensure the stability of the output voltage Vout, the second feedback resistor R2 The resistance value must also decrease with the increase of temperature, therefore, the thermistor Rt uses a negative temperature coefficient thermistor.

In the above embodiment, the first switching transistor Q1 may be an NPN transistor or an NMOS transistor. Similarly, the second switching transistor Q2 may be an NPN transistor or an NMOS transistor.

When both the first switch tube Q1 and the second switch tube Q2 are NPN transistors, refer to FIG. 2 and FIG. 3 for the circuit diagram of the voltage stabilizing circuit.

When both the first switching tube Q1 and the second switching tube Q2 are NMOS tubes, see FIG. 4 and FIG. 5 for the circuit diagram of the voltage stabilizing circuit.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

The above description of the disclosed embodiments enables those skilled in the art to realize or use the utility model. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. A voltage stabilizing circuit, characterized in that it comprises: a DC power supply, a first switch tube, a second switch tube, a pull-up resistor, a first feedback resistor and a second feedback resistor, wherein the first feedback resistor and the The difference between the total resistance of the second feedback resistor and the load resistance of the voltage stabilizing circuit exceeds a preset resistance; The input terminal of the first switch tube is connected to the DC power supply, the output terminal of the first switch tube is connected to the ground terminal through the first feedback resistor and the second feedback resistor connected in series, and the first switch tube The terminal voltage of the output terminal of the tube and the common terminal of the first feedback resistor is used as the output voltage of the voltage stabilizing circuit; The input terminal of the second switch tube is connected to the control terminal of the first switch tube, the output terminal of the second switch tube is connected to the ground terminal, and the control terminal of the second switch tube is connected to the first feedback resistor and the common end of the second feedback resistor; One end of the pull-up resistor is connected to the DC power supply, and the other end is connected to the control end of the first switch tube. 2. The voltage stabilizing circuit according to claim 1, further comprising: a voltage stabilizing capacitor; The positive plate of the voltage stabilizing capacitor is connected to the common terminal of the first switch tube and the first feedback resistor, and the negative plate is connected to the ground terminal. 3. The voltage stabilizing circuit according to claim 1, further comprising: a thermistor; One end of the thermistor is connected to the common end of the second switch tube and the first feedback resistor, and the other end of the thermistor is connected to a ground terminal through the second feedback resistor. 4. The voltage stabilizing circuit according to claim 3, wherein the thermistor is a negative temperature coefficient thermistor. 5. The voltage stabilizing circuit according to claim 1, wherein the first switch tube is an NPN transistor. 6. The voltage stabilizing circuit according to claim 1, wherein the first switching transistor is an NMOS transistor. 7. The voltage stabilizing circuit according to claim 1, wherein the second switch tube is an NPN transistor. 8. The voltage stabilizing circuit according to claim 1, wherein the second switching transistor is an NMOS transistor.