A voltage stabilizing circuit

Abstract

The application provides a voltage stabilizing circuit, comprising a reference source, an anode of the reference source being connected to ground, a voltage sampling unit, the voltage sampling unit sampling an output voltage and outputting a control signal, the reference source being controlled by the control signal, a feedback unit, a first output port of the feedback unit being connected to the reference source in parallel, a second output port of the feedback unit being connected to the voltage sampling unit in parallel, and an input end of the feedback unit being connected to a power supply; if a voltage of the control signal does not reach a reference voltage of the reference source, a line between the feedback unit and a first end of a load is turned on, the power supply is connected to the load, and the output voltage rises; once the output voltage rises to a set value, the reference source shorts the load, the current in the feedback unit decreases, the output voltage decreases and is stabilized at the set value. The application has a wide application range while being simple in design and high in stability.

Description

Technical Field

[0001] This invention relates to the field of power management chip technology, and in particular to a voltage regulator circuit. Background Technology

[0002] Today, portable electronic devices, represented by smartphones, are developing rapidly and playing a vital role in the economy and society. High-performance power management chips are fundamental to advanced portable electronic devices and are a basic requirement for ensuring the normal operation of electronic systems. External power supplies inevitably contain high-frequency noise or ripple voltage. These high-frequency noise voltages typically propagate within the electronic system through coupling capacitors and DC paths. When the amplitude of the noise signal is comparable to that of the normal signal, the electronic system cannot function properly. The main function of power management chips is to reduce high-frequency noise in the electronic system's power supply, improve the power supply rejection ratio, and suppress the impact of output load current variations on the power supply voltage. Common power management chips include low-dropout linear regulators (LDOs), which are increasingly widely used due to their advantages such as high integration, low noise, low quiescent current, and simple structure.

[0003] Power supply protection measures are crucial for the entire electronic system, including overvoltage, overcurrent, and overheat protection. When electronic products malfunction, such as a short circuit on the input side or an open circuit on the output side, the power supply must disconnect its output voltage to prevent damage to power and output-side equipment. However, simply shutting off the power supply is not appropriate; the circuit must also be able to resume operation after the overcurrent event is resolved. Therefore, designing a low-dropout linear regulator circuit with overcurrent protection is essential. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides a voltage regulator circuit, which adopts the following technical solution:

[0005] A voltage regulator circuit includes a reference source, wherein the anode of the reference source is grounded.

[0006] A voltage sampling unit samples the voltage across the load and outputs a control signal; the reference source is controlled by the control signal.

[0007] The feedback unit has a first output port connected in parallel with the reference source, a second output port connected in parallel with the voltage sampling unit, and an input terminal connected to a power supply.

[0008] If the voltage of the control signal does not reach the reference voltage of the reference source, the reference source cannot short-circuit the load, the line between the feedback unit and the load is connected, the power supply is connected to the load, and the voltage across the load rises; once the voltage across the load rises to the set value, the voltage of the corresponding control signal will also reach the reference voltage of the reference source, the reference source short-circuits the load, the current in the feedback unit decreases, and since the line between the feedback unit and the load is connected, the voltage across the load drops, and the voltage across the load stabilizes at the set value.

[0009] The implementation can include any or all of the following features.

[0010] Furthermore, the feedback unit includes a first resistor, a first end of which is connected to the power supply, and a second end of which is connected to the cathode of the reference source;

[0011] A switching module includes a first switch, the emitter of which is connected to the power supply, and the base of which is connected to a first terminal of the load.

[0012] A second switch, the base of which is connected to the collector of the first switch, and the emitter of which is connected to the power supply.

[0013] A third switch, the base of which is connected to the collector of the second switch, the collector of which is connected to the power supply, and the emitter of which is connected to the base of the first switch.

[0014] A fourth switch, the collector of which is connected to the base of the second switch, the base of which is connected to the second terminal of the first resistor, and the emitter of which is connected to the anode of the reference source.

[0015] Furthermore, the feedback unit also includes an overcurrent protection module, which includes a second resistor. The first end of the second resistor is connected to the emitter of the first switch, and the second end of the second resistor is connected to the collector of the third switch.

[0016] A third resistor, the first end of which is connected to the second end of the second resistor, and the second end of which is connected to the base of the first switch.

[0017] A fourth resistor, the first end of which is connected to the base of the first switch, and the second end of which is connected to the emitter of the third switch.

[0018] Furthermore, the voltage sampling unit includes a fifth resistor and a sixth resistor, which are connected in series, and the control signal is output at the midpoint of the series connection between the fifth resistor and the sixth resistor.

[0019] Furthermore, it also includes a capacitor, one end of which is connected to the cathode of the reference source, and the other end of which is connected to the control electrode of the reference source.

[0020] Furthermore, the switching module also includes a diode, the anode of which is connected to the anode of the reference source, and the cathode of which is connected to the emitter of the fourth switch.

[0021] Furthermore, the switch module also includes a seventh resistor, one end of which is connected to the power supply, and the other end of which is connected to the emitter of the second switch.

[0022] Furthermore, the switch module also includes an eighth resistor, one end of which is connected to the power supply, and the other end of which is connected to the base of the second switch.

[0023] Furthermore, the switching module also includes a ninth resistor, one end of which is connected to the base of the second switch, and the other end of which is connected to the collector of the fourth switch.

[0024] In the above technical solution of the present invention, the set value of the output voltage is designed by the reference source in conjunction with the voltage sampling unit, and the output voltage is stabilized at the set value by the different connection methods between the switches in the switching module and the connection relationship between the switching module and the reference source. The set value can be adjusted by the voltage sampling unit. Furthermore, the feedback unit can automatically reduce the output current when the output current is too high due to the load short circuit, so as to prevent the third switch from overheating and being damaged.

[0025] In summary, the voltage regulator circuit of this invention can adjust the output voltage to the voltage required by the load according to actual needs when the power supply voltage is singular. It can also detect overcurrent and adaptively reduce the current on the power transistor to achieve foldback current limiting, thus avoiding damage to the power transistor due to prolonged high current during the overcurrent protection phase. The design is simple, highly stable, and has a wide range of applications. Attached Figure Description

[0026] Figure 1 The diagram shown is a structural block diagram of a voltage regulator circuit according to the present invention.

[0027] Figure 2 This is shown as a specific embodiment of the present invention.

[0028] Explanation of reference numerals in the attached diagram:

[0029] 1-Voltage regulator circuit; 11-Feedback unit; 111-Overcurrent protection module; 112-Switching module; 12-Reference unit; 13-Voltage sampling unit. Detailed Implementation

[0030] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] like Figure 1 As shown, the present invention provides a voltage regulator circuit 1, including a feedback unit 11, a reference unit 12, and a voltage sampling unit 13. The voltage sampling unit 13 is connected in parallel with a load RL, and the first terminal of the load RL outputs a voltage V. out The control signal CTL1 output by the voltage sampling unit 13 is input to the first terminal of the reference unit 12. The second terminal of the reference unit 12 is connected to the ground terminal GND. The second terminal and the third terminal of the reference unit 12 are connected in parallel to the first output port of the feedback unit 11. The voltage sampling unit 13 is connected in parallel to the second output port of the feedback unit 11. The input terminal O of the feedback unit 11 is... in Input voltage V in If the voltage V out The set value was not reached, and the set value does not exceed the voltage V. in The voltage value is such that the corresponding control signal CTL1 voltage does not reach the reference voltage of the reference unit 12, the reference unit 12 cannot short-circuit the load RL, the feedback unit 11 is turned on, and the line between the feedback unit 11 and the load RL is thus connected, and the voltage V... out Rise; once the voltage V out As the voltage rises to the set value, the corresponding control signal CTL1 reaches the reference voltage of the reference unit 12. The reference unit 12 short-circuits the load RL, and the current in the feedback unit 11 decreases. Since the line between the feedback unit 11 and the first terminal of the load RL is now connected, the voltage V... out The voltage V decreases, and the above circuit structure ensures that the voltage V is maintained. out It stabilizes at the set value.

[0032] like Figure 2As shown, the present invention provides a voltage regulator circuit 1, including a feedback unit 11, a reference unit 12, and a voltage sampling unit 13. The voltage sampling unit 13 is connected in parallel with a load RL, and the first terminal of the load RL outputs a voltage V. out The control signal CTL1 output by the voltage sampling unit 13 is input to the first terminal of the reference unit 12. The second terminal of the reference unit 12 is connected to the ground terminal GND. The second terminal and the third terminal of the reference unit 12 are connected in parallel to the first output port of the feedback unit 11. The voltage sampling unit 13 is connected in parallel to the second output port of the feedback unit 11. The input terminal O of the feedback unit 11 is... in Input voltage V in .

[0033] The feedback unit 11 includes a resistor R7, an overcurrent protection module 111, and a switching module 112. The first end of the resistor R7 is connected to the input terminal O. in The second end of resistor R7 is connected to the third end of reference unit 12. Switch module 112 is connected to the third end of reference unit 12 via resistor R7. Overcurrent protection module 111 provides a current foldback path for switch module 112. Overcurrent protection module 111 includes resistors R3, R4, and R5. The first end of resistor R3 is connected to the first end of resistor R7. The first end of resistor R4 is connected to the second end of resistor R3. The first end of resistor R5 is connected to the second end of resistor R4. The second end of resistor R5 is connected to the first end of load RL. Resistors R3, R4, and R5 are connected in series. In this embodiment, the resistance value of resistor R3 is very small.

[0034] The switching module 112 includes a resistor R1, a switch Q1, a switch Q2, a resistor R2, a switch Q3, a resistor R6, a switch Q4, and a diode ZD1. The emitter of switch Q1 is connected to the first terminal of resistor R3, the base of switch Q1 is connected to the midpoint of the series connection of resistors R4 and R5, the collector of switch Q1 is connected to the base of switch Q2, the collector of switch Q2 is connected to the base of switch Q3, the collector of switch Q3 is connected to the midpoint of the series connection of resistors R3 and R4, the emitter of switch Q3 is connected to the first terminal of the load RL, the emitter of switch Q2 is connected to the first terminal of resistor R1, and the second terminal of resistor R1 is connected to... The emitter of switch Q1 is connected to the base of switch Q2, the first end of resistor R2 is connected to the second end of resistor R2, the first end of resistor R6 is connected to the base of switch Q2, the second end of resistor R6 is connected to the collector of switch Q4, the base of switch Q4 is connected to the second end of resistor R7, the emitter of switch Q4 is connected to the cathode of diode ZD1, and the anode of diode ZD1 is connected to the second end of load RL. Switch Q4 controls the conduction and cutoff of switch Q2, and switch Q2 controls the conduction and cutoff of switch Q3. Resistors R1 and R6 both serve as current limiters, and resistor R2 serves as an anti-interference device. In this embodiment, switches Q1 and Q2 are both PNP transistors, switches Q3 and Q4 are both NPN transistors, and diode ZD1 is a Zener diode.

[0035] The reference unit 12 includes a reference source U1 and a capacitor C1. The anode of the reference source U1 is connected to the anode of the diode ZD1, and the cathode of the reference source U1 is connected to the second terminal of the resistor R7. The control electrode of the reference source U1 is connected inside the voltage sampling unit 13. The first terminal of the capacitor C1 is connected to the control electrode of the reference source U1, and the second terminal of the capacitor C1 is connected to the cathode of the reference source U1. The capacitor C1 is a compensation capacitor to prevent the reference source U1 from oscillating. Preferably, the reference source U1 is a TL431 with an internal reference voltage of 2.5V. If the input voltage to the control electrode of the reference source U1 is less than 2.5V, the reference source U1 is turned off; otherwise, the reference source U1 is turned on.

[0036] The voltage sampling unit 13 includes resistors R8 and R9 connected in series. The control signal CTL1 is output at the midpoint of the series connection between resistors R8 and R9. The control electrode of the reference source U1 is connected to the midpoint of the series connection between resistors R8 and R9. The control signal CTL1 controls the conduction and cutoff of the reference source U1.

[0037] The voltage stabilization principle of this invention is as follows: This invention controls the voltage V out Stabilize at a set value, wherein the set value does not exceed the voltage V in Adjust the resistance values ​​of resistors R8 and R9 so that the voltage of the control signal CTL1 (i.e., the voltage across resistor R9) is equal to the reference voltage of the reference source U1.

[0038] If the voltage V out If the set value is not reached, the voltage V out The voltage of the control signal CTL1 obtained after voltage division by the voltage sampling unit 13 also does not reach the reference voltage of the reference source U1, so the reference source U1 is cut off; because the input terminal O in The base of switch Q4 is connected via resistor R7, and the emitter of switch Q4 is connected to ground GND via diode ZD1, thus turning on switch Q4. Since the base of switch Q2 is connected to ground GND via resistor R6, switch Q4, and diode ZD1, and the emitter of switch Q2 is connected to input terminal O via resistor R1... in The base potential of switch Q2 is pulled low, and switch Q2 is turned on; since the base of switch Q3 is connected to the input terminal O through switch Q2 and resistor R1. in Furthermore, the emitter of switch Q3 is connected to the first terminal of the load RL, thus turning on switch Q3; the input terminal O in The first terminal of the load RL is connected via the resistor R3 and the switch Q3, and the voltage V out It was able to rise.

[0039] Once the voltage V out The voltage V increases to the set value. out After voltage division by the voltage sampling unit 13, the voltage of the control signal CTL1 also reaches the reference voltage of the reference source U1, and the reference source U1 is turned on. Since the base of the switch Q4 is connected to the ground terminal GND through the reference source U1, and the emitter of the switch Q4 is connected to the ground terminal GND through the diode ZD1, the current flowing through the switch Q4 decreases due to the conduction of the reference source U1; correspondingly, the current flowing through the switch Q2 also decreases; the current flowing through the switch Q3 also decreases, and the voltage V... out This can be reduced.

[0040] The overcurrent protection principle of this invention is as follows: When the load RL is short-circuited, causing the output current to be too high, since the resistor R3 is connected to the first terminal of the load RL through the switch Q3, and the emitter and base of the switch Q1 are connected in series through the resistors R3 and R4, the switch Q1 is turned on; since the base of the switch Q2 is connected to the collector of the switch Q1, and the emitter of the switch Q2 is connected to the input terminal O through the resistor R1, the overcurrent protection principle of this invention is as follows: When the load RL is short-circuited, causing the output current to be too high, the resistor R3 is connected to the first terminal of the load RL through the switch Q3, and the emitter of the switch Q2 is connected to the input terminal O through the resistor R1. in Although switch Q2 is not completely off, its conduction capability is reduced, resulting in a decrease in the current flowing from switch Q2 to switch Q3. Since the base of switch Q3 is connected to the input terminal O via switch Q2 and resistor R1... in The emitter of the switch Q3 is connected to the first terminal of the load RL. Although the switch Q3 is not completely turned off, its conduction capability is reduced, and the output current is reduced.

[0041] Simultaneously, when the load RL is short-circuited, the voltage V out The voltage value is 0, because the input terminal O in The first terminal of the load RL is connected via the resistor R3 and the switch Q3. Since the resistance of resistor R3 is very small, the voltage across switch Q3 is approximately equal to the voltage V. in The power of the switch Q3 is approximately equal to the output current and the voltage V. in The product of the two factors reduces the output current, protecting switch Q3 from overheating and damage.

[0042] This invention designs the set value using the reference source U1 in conjunction with the voltage sampling unit 13. The voltage V is determined by different connection methods between the switches in the switching module 112 and the connection relationship between the switching module 112 and the reference source U1. out The circuit stabilizes at the set value, which can be adjusted by the resistance ratio of resistors R8 and R9 within the voltage sampling unit 13. This design simplifies the circuit and broadens its application range. Furthermore, the feedback unit 11 can automatically reduce the output current when the output current is too high due to a short circuit in the load RL, preventing the switch Q3 from overheating and being damaged, thereby improving the overall circuit stability.

[0043] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of the present invention.

Claims

1. A voltage regulator circuit, wherein the output terminal of the voltage regulator circuit is connected to a load, characterized in that: Including the reference source, the The anode of the reference source is grounded. A voltage sampling unit samples the voltage across the load and outputs a control signal; the reference source is controlled by the control signal. The feedback unit has a first output port connected in parallel with the reference source, a second output port connected in parallel with the voltage sampling unit, and an input terminal connected to a power supply. If the voltage of the control signal does not reach the reference voltage of the reference source, the reference source cannot short-circuit the load, the line between the feedback unit and the load is connected, the power supply is connected to the load, and the voltage across the load rises. Once the voltage across the load rises to the set value, the corresponding voltage of the control signal will also reach the reference voltage of the reference source, the reference source short-circuits the load, the current in the feedback unit decreases, and since the line between the feedback unit and the load is now connected, the voltage across the load drops and stabilizes at the set value. The feedback unit includes: A first resistor, with its first end connected to the power supply and its second end connected to the cathode of the reference source. A switching module includes a first switch, the emitter of which is connected to the power supply, and the base of which is connected to a first terminal of the load. A second switch, the base of which is connected to the collector of the first switch, and the emitter of which is connected to the power supply. A third switch, the base of which is connected to the collector of the second switch, the collector of which is connected to the power supply, and the emitter of which is connected to the base of the first switch. A fourth switch, the collector of which is connected to the base of the second switch, the base of which is connected to the second terminal of the first resistor, and the emitter of which is connected to the anode of the reference source.

2. The voltage regulator circuit according to claim 1, characterized in that: The feedback unit further includes an overcurrent protection module, which includes a second resistor. The first end of the second resistor is connected to the emitter of the first switch, and the second end of the second resistor is connected to the collector of the third switch. The first end of the third resistor is connected to the second end of the second resistor, and the second end of the third resistor is connected to the base of the first switch. A fourth resistor, the first end of which is connected to the base of the first switch, and the second end of which is connected to the emitter of the third switch.

3. A voltage regulator circuit according to claim 2, characterized in that: The voltage sampling unit includes a fifth resistor and a sixth resistor, which are connected in series. The control signal is output at the midpoint of the series connection between the fifth resistor and the sixth resistor.

4. A voltage regulator circuit according to claim 3, characterized in that: It also includes a capacitor, one end of which is connected to the cathode of the reference source, and the other end of which is connected to the control electrode of the reference source.

5. A voltage regulator circuit according to claim 4, characterized in that: The switching module also includes a diode, the anode of which is connected to the anode of the reference source, and the cathode of which is connected to the emitter of the fourth switch.

6. A voltage regulator circuit according to claim 5, characterized in that: The switching module also includes a seventh resistor, one end of which is connected to the power supply, and the other end of which is connected to the emitter of the second switch.

7. A voltage regulator circuit according to claim 6, characterized in that: The switching module further includes an eighth resistor, one end of which is connected to the power supply, and the other end of which is connected to the base of the second switch.

8. A voltage regulator circuit according to claim 7, characterized in that: The switching module further includes a ninth resistor, one end of which is connected to the base of the second switch, and the other end of which is connected to the collector of the fourth switch.

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