Low-cost low-dropout linear voltage regulator protection circuit
By using a low-dropout linear voltage regulator protection circuit composed of discrete components and a combination of field-effect transistors and bipolar transistors for control, the high cost problem in existing technologies is solved, achieving low-cost voltage regulation and strong anti-interference capabilities. It is suitable for mobile devices, wireless communication devices and analog radio frequency circuits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CONHUI HUIZHOU SEMICON
- Filing Date
- 2025-07-24
- Publication Date
- 2026-07-07
AI Technical Summary
Existing low-dropout linear voltage regulator circuits use dedicated voltage regulator chips, which are costly and make it difficult to achieve a low-cost voltage regulation solution.
A low-dropout linear voltage regulator protection circuit is composed of discrete components. The circuit uses a combination of field-effect transistors and transistors to control the output voltage through a feedback network, eliminating the need for a dedicated voltage regulator chip.
It achieves low-cost voltage regulation and has strong anti-interference capabilities, making it suitable for electronic devices that require low noise and high precision.
Smart Images
Figure CN224473206U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of low dropout linear voltage regulator circuits, and in particular to a low-cost low dropout linear voltage regulator protection circuit. Background Technology
[0002] A low-dropout linear regulator is a commonly used voltage regulator. Its function is to convert an unstable or high-voltage input power supply into a stable, lower output voltage.
[0003] Low-dropout linear regulators are widely used in various electronic devices, especially in applications requiring low noise and high-precision power supplies. For example, mobile devices, wireless communication devices, analog and radio frequency circuits all use low-dropout linear regulators to provide reliable power.
[0004] Existing low-dropout linear voltage regulator circuits are usually implemented using dedicated voltage regulator chips plus some peripheral circuits, and dedicated chips are relatively expensive. Utility Model Content
[0005] The purpose of this invention is to provide a low-cost, low-dropout linear voltage regulator protection circuit, which uses discrete components to form the low-dropout linear voltage regulator protection circuit, thus eliminating the need for a dedicated voltage regulator chip.
[0006] To achieve the above objectives, this utility model adopts the following technical solution: a low-cost, low-dropout linear voltage regulator protection circuit, comprising: a VCC input terminal, a VCC output terminal, a field-effect transistor Q1, a transistor Q7, a diode D2, a Zener diode D3, a capacitor C2, resistors R3, R4, R5, and R6. The VCC input terminal and the VCC output terminal are respectively connected to the source and drain of the field-effect transistor Q1, and the resistor R3 is connected between the gate of the field-effect transistor Q1 and the collector of the transistor Q7. Between these terminals, the positive and negative terminals of the Zener diode D3 are grounded to the base of the transistor Q7, the resistor R5 is connected between the emitter of the transistor Q7 and the VCC output terminal, the resistor R6 is connected between the emitter of the transistor Q7 and ground, the negative terminal of the diode D2 is connected to the base of the transistor Q7, the resistor R4 is connected between the drain of the field-effect transistor Q1 and the positive terminal of the diode D2, one end of the capacitor C2 is connected between the resistor R6 and ground, and the other end of the capacitor C2 is connected to the VCC output terminal.
[0007] Preferably, the low-cost, low-dropout linear voltage regulator protection circuit further includes a diode D1, wherein the positive and negative terminals of the diode D1 are respectively connected to the collector of the transistor Q7 and the source of the field-effect transistor Q1.
[0008] Preferably, the low-cost, low-dropout linear voltage regulator protection circuit further includes a resistor R2, which is connected between the source of the field-effect transistor Q1 and the collector of the transistor Q7.
[0009] Preferably, the low-cost, low-dropout linear voltage regulator protection circuit further includes a resistor R1, which is connected between the source of the field-effect transistor Q1 and the base of the transistor Q7.
[0010] Preferably, the low-cost, low-dropout linear voltage regulator protection circuit further includes a capacitor C1, which is connected between the base of the transistor Q7 and ground.
[0011] Preferably, the transistor Q7 is an NPN transistor.
[0012] Preferably, the field-effect transistor Q1 is a P-channel MOSFET.
[0013] Preferably, both diode D1 and diode D2 are rectifier diodes.
[0014] Preferably, the low-cost, low-dropout linear voltage regulator protection circuit further includes a voltage acquisition module, which is connected in parallel with resistor R6.
[0015] Furthermore, VFB = VBE = r6 / (r5+r6)*VCC_OUT, where VFB is the feedback voltage, VCC_OUT is the output voltage at the VCC output terminal, r5 is the resistance value of resistor R5, r6 is the resistance value of resistor R6, and VBE is the voltage between the base and emitter of transistor Q7.
[0016] Furthermore, VREF = VZ + VBE(sat), where VREF is the reference voltage, VZ is the voltage of Zener diode D3 when it is in breakdown state, and VBE(sat) is the voltage between the base and emitter of transistor Q7 in saturation state.
[0017] The working principle of this utility model is as follows: When the output voltage VCC_OUT is too low, the feedback voltage is obtained by sampling through the feedback network (resistor voltage divider). At this time, VFB=R6 / (R5+R6)*VCC_OUT<VREF=VZ+VBE(sat), the transistor Q7 enters the saturation state, VGS<VGS(th), the field-effect transistor Q1 is turned on, and the output VCC_OUT voltage is increased.
[0018] When the output voltage VCC_OUT is too high, when R6 / (R5+R6)*VCC_OUT>VZ+VBE(sat), the transistor Q7 enters the cutoff state, VGS>VGS(th), the field-effect transistor Q1 is cut off, there is no current output, and the output VCC_OUT voltage is reduced.
[0019] Where VGS is the gate voltage relative to the source, and VGS(th) is the minimum gate bias voltage that can form a conductive channel between the source and drain.
[0020] The beneficial effects of this invention are as follows: By controlling the operating state of transistor Q7, the conduction or cutoff of field-effect transistor Q1 is controlled. When transistor Q7 is in saturation, field-effect transistor Q1 conducts, increasing VCC_OUT. When transistor Q7 is in cutoff, field-effect transistor Q1 is cut off, decreasing VCC_OUT. This invention utilizes discrete components to achieve low-dropout linear voltage regulation, eliminating the need for dedicated chips and offering advantages such as low cost and strong anti-interference capability. Attached Figure Description
[0021] The accompanying drawings further illustrate the present invention, but the embodiments in the drawings do not constitute any limitation on the present invention.
[0022] Figure 1 A circuit diagram provided for one embodiment of this utility model. Detailed Implementation
[0023] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.
[0024] It should be noted that, in this utility model, unless otherwise stated, when an element is referred to as being "connected" between two other elements, it means that it is directly connected to another element or that an intervening element may be present at the same time.
[0025] like Figure 1 As shown in the figure, an embodiment of this utility model provides a low-cost, low-dropout linear voltage regulator protection circuit, including: a VCC input terminal, a VCC output terminal, a field-effect transistor Q1, a transistor Q7, a diode D2, a Zener diode D3, a capacitor C2, resistors R3, R4, R5, and R6. The VCC input terminal and VCC output terminal are respectively connected to the source and drain of the field-effect transistor Q1. The resistor R3 is connected between the gate of the field-effect transistor Q1 and the collector of the transistor Q7. The positive and negative terminals of the Zener diode D3 are grounded to the base of the transistor Q7, respectively. The resistor R5 is connected between the emitter of the transistor Q7 and the VCC output terminal. The resistor R6 is connected between the emitter of the transistor Q7 and ground. The negative terminal of the diode D2 is connected to the base of the transistor Q7. The resistor R4 is connected between the drain of the field-effect transistor Q1 and the positive terminal of the diode D2. One end of the capacitor C2 is connected between the resistor R6 and ground, and the other end of the capacitor C2 is connected to the VCC output terminal.
[0026] The low-cost, low-dropout linear voltage regulator protection circuit also includes a diode D1, whose anode and cathode are connected to the collector of transistor Q7 and the source of field-effect transistor Q1, respectively. Diode D1 provides overvoltage protection, preventing excessive voltage between field-effect transistor Q1 and transistor Q7.
[0027] The low-cost, low-dropout linear voltage regulator protection circuit also includes a resistor R2, which is connected between the source of the field-effect transistor Q1 and the collector of the transistor Q7. The voltage is divided by resistor R2 to prevent excessive voltage between the field-effect transistor Q1 and the transistor Q7.
[0028] The low-cost, low-dropout linear voltage regulator protection circuit also includes a resistor R1, which is connected between the source of the field-effect transistor Q1 and the base of the transistor Q7. The voltage is divided by the resistor R1 to prevent excessive voltage between the field-effect transistor Q1 and the transistor Q7.
[0029] The low-cost, low-dropout linear voltage regulator protection circuit also includes a capacitor C1, which is connected between the base of transistor Q7 and ground. The resistor and capacitor enhance the anti-interference capability.
[0030] The transistor Q7 is an NPN transistor.
[0031] The field-effect transistor Q1 is a P-channel MOSFET.
[0032] Both diodes D1 and D2 are rectifier diodes.
[0033] The low-cost, low-dropout linear voltage regulator protection circuit also includes a voltage acquisition module, which is connected in parallel with resistor R6.
[0034] VFB = VBE = r6 / (r5+r6)*VCC_OUT, where VFB is the feedback voltage, VCC_OUT is the output voltage at the VCC output terminal, r5 is the resistance value of resistor R5, r6 is the resistance value of resistor R6, and VBE is the voltage between the base and emitter of transistor Q7.
[0035] VREF = VZ + VBE(sat), where VREF is the reference voltage, VZ is the voltage of Zener diode D3 when it is in breakdown state, and VBE(sat) is the voltage between the base and emitter of transistor Q7 in saturation state.
[0036] When the output voltage VCC_OUT is too low, the feedback voltage is obtained by sampling through the feedback network (resistor voltage divider). At this time, VFB=R6 / (R5+R6)*VCC_OUT<VREF=VZ+VBE(sat), the transistor Q7 enters the saturation conduction state, VGS<VGS(th), the field effect transistor Q1 is turned on, and the output VCC_OUT voltage is increased.
[0037] When the output voltage VCC_OUT is too high, when R6 / (R5+R6)*VCC_OUT>VZ+VBE(sat), the transistor Q7 enters the cutoff state, VGS>VGS(th), the field-effect transistor Q1 is turned off, there is no current output, and the output VCC_OUT voltage is reduced.
[0038] Where VGS is the gate voltage relative to the source, and VGS(th) is the minimum gate bias voltage that can form a conductive channel between the source and drain.
[0039] The technical features of the embodiments described above can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this utility model, and these should all be considered to be within the scope of this specification.
Claims
1. A low-cost, low-dropout linear voltage regulator protection circuit, characterized in that: include: The system consists of a VCC input terminal, a VCC output terminal, a field-effect transistor (FET) Q1, a transistor Q7, a diode D2, a Zener diode D3, a capacitor C2, and resistors R3, R4, R5, and R6. The VCC input terminal and VCC output terminal are connected to the source and drain of FET Q1, respectively. Resistor R3 is connected between the gate of FET Q1 and the collector of transistor Q7. The anode and cathode of Zener diode D3 are grounded to the base of transistor Q7, respectively. Resistor R5 is connected between the emitter of transistor Q7 and the VCC output terminal. Resistor R6 is connected between the emitter of transistor Q7 and ground. The cathode of diode D2 is connected to the base of transistor Q7. Resistor R4 is connected between the drain of FET Q1 and the anode of diode D2. One end of capacitor C2 is connected between resistor R6 and ground, and the other end of capacitor C2 is connected to the VCC output terminal.
2. The low-cost, low-dropout linear voltage regulator protection circuit according to claim 1, characterized in that: It also includes a diode D1, the positive and negative terminals of which are connected to the collector of transistor Q7 and the source of field-effect transistor Q1, respectively.
3. The low-cost, low-dropout linear voltage regulator protection circuit according to claim 1, characterized in that: It also includes a resistor R2, which is connected between the source of the field-effect transistor Q1 and the collector of the transistor Q7.
4. The low-cost, low-dropout linear voltage regulator protection circuit according to claim 1, characterized in that: It also includes a resistor R1, which is connected between the source of the field-effect transistor Q1 and the base of the transistor Q7.
5. The low-cost, low-dropout linear voltage regulator protection circuit according to claim 4, characterized in that: It also includes capacitor C1, which is connected between the base of transistor Q7 and ground.
6. The low-cost, low-dropout linear voltage regulator protection circuit according to claim 1, characterized in that: The transistor Q7 is an NPN transistor.
7. The low-cost, low-dropout linear voltage regulator protection circuit according to claim 1, characterized in that: The field-effect transistor Q1 is a P-channel MOSFET.
8. The low-cost, low-dropout linear voltage regulator protection circuit according to claim 2, characterized in that: Both diodes D1 and D2 are rectifier diodes.
9. The low-cost, low-dropout linear voltage regulator protection circuit according to claim 1, characterized in that: VFB = r6 / (r5 + r6) * VCC_OUT, where VFB is the feedback voltage, VCC_OUT is the output voltage at the VCC output terminal, r5 is the resistance value of resistor R5, and r6 is the resistance value of resistor R6.
10. The low-cost, low-dropout linear voltage regulator protection circuit according to claim 1, characterized in that: VREF = VZ + VBE(sat), where VREF is the reference voltage, VZ is the voltage of Zener diode D3 when it is in breakdown state, and VBE(sat) is the voltage between the base and emitter of transistor Q7 in saturation state.