A high-stability low-dropout linear voltage regulator

Abstract

The application provides a high-stability low-dropout linear voltage regulator, which comprises a power tube, an error amplifier and a compensation circuit, wherein the power tube outputs a load current; the error amplifier is used for controlling the conduction degree of the power tube according to a difference signal of a feedback voltage and a first reference voltage, thereby affecting the size of the load current; and the compensation circuit is used for compensating the difference signal according to a load condition, when the load is a first type of load, compensating the difference by a current signal equal to the load current, and performing a first type of correction on the voltage of the control end of the power tube, and when the load is a second type of load, compensating the difference signal by a current signal which changes along with the load current, and performing a second type of correction on the voltage of the control end of the power tube. According to different loads, different compensation values are set to reduce the influence of different poles, and the stability of the low-dropout linear voltage regulator can be enhanced.

Description

Technical Field

[0001] This invention relates to the field of electronic technology, specifically but not limited to a highly stable low-dropout linear regulator. Background Technology

[0002] Figure 1 This diagram illustrates a common low-dropout linear regulator (LDO). Its basic function is as follows: the output of the error amplifier (EA) controls the conduction level of the power transistor (MP). When the output voltage increases, the output of the error amplifier increases, and the conduction level of the power transistor decreases, thus suppressing the increase in output voltage; conversely, when the output voltage decreases, the output of the error amplifier decreases, and the conduction level of the power transistor increases, thus suppressing the decrease in output voltage. Therefore, the low-dropout linear regulator can maintain the output voltage near the normal operating voltage.

[0003] However, the load of a low-dropout linear regulator has a very wide range of variation. Therefore, there are multiple poles in the loop of a low-dropout linear regulator. These poles will cause the stability of the low-dropout linear regulator to deteriorate, resulting in the output voltage deviating from the normal operating voltage.

[0004] In view of this, there is a need to provide a new structure or control method in order to solve at least some of the above problems. Summary of the Invention

[0005] In response to at least one or more of the problems in the background art, the present invention proposes a highly stable low-dropout linear regulator that can reduce the influence of poles, thereby improving circuit stability.

[0006] One embodiment of the present invention provides a highly stable low-dropout linear regulator, comprising:

[0007] Power transistor;

[0008] An error amplifier has a first input terminal coupled to a feedback voltage and a second input terminal coupled to a first reference voltage. The error amplifier is used to control the conduction degree of the power transistor based on the difference signal between the feedback voltage and the first reference voltage.

[0009] The compensation circuit is used to compensate the difference signal according to the load condition. When the load is a Class I load, the difference signal is compensated with a current signal equal to the load current. When the load is a Class II load, the difference signal is compensated with a current signal that follows the load current.

[0010] Optionally, the first type of load is an ultra-light load, and the second type of load is a light load.

[0011] Optionally, the compensation circuit includes an ultra-light load compensation circuit, which includes: a first comparison circuit for comparing the load current with the reference current and outputting the comparison result; and a first control unit for determining whether to compensate the difference signal based on the comparison result. If the load current is less than the reference current, the difference signal is compensated with a current signal equal to the load current.

[0012] Optionally, the first comparison circuit includes: a first current source for generating a reference current; and a first current mirror having a reference current terminal and a bias current terminal, wherein the reference current terminal is coupled to the load current and the bias current terminal is coupled to the output terminal of the first current source.

[0013] Optionally, the first control unit includes: a second current mirror having a reference current terminal and a bias current terminal, the reference current terminal being coupled to the load current; and a thirty-eighth transistor having an input terminal, an output terminal, and a control terminal, the input terminal being coupled to the output terminal of the error amplifier, the output terminal being coupled to the bias current terminal of the second current mirror, and the control terminal being coupled to the first current source; the control terminal is used to determine whether the thirty-eighth transistor is turned on based on the comparison result between the load current and the reference current.

[0014] Optionally, the compensation circuit further includes a light-load compensation circuit, which includes: a third current mirror having a reference current terminal and a bias current terminal, the reference current terminal being coupled to the load current; a fourth current mirror having a reference current terminal and a bias current terminal, the reference current terminal being coupled to the bias current terminal of the third current mirror; and a variable resistor circuit having an input terminal, an output terminal, and a control terminal, the input terminal being coupled to the output terminal of the error amplifier, the output terminal being coupled to a reference ground, and the control terminal being coupled to the bias current terminal of the fourth current mirror; the internal resistance value of the variable resistor circuit changes with the bias current value of the fourth current mirror.

[0015] Optionally, the adjustable resistor circuit includes: a thirty-second transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to a load current; and its control terminal is coupled to the control terminal of the thirty-first transistor; a thirty-third transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the second terminal of the thirty-second transistor, and its control terminal is coupled to the control terminal of the thirty-first transistor; a thirty-fourth transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the second terminal of the thirty-third transistor, and its control terminal is coupled to the control terminal of the thirty-first transistor; and a thirty-fifth transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the second terminal of the thirty-fourth transistor, the second terminal is coupled to a reference ground, and its control terminal is coupled to the control terminal of the thirty-first transistor.

[0016] Optionally, the low-dropout linear regulator further includes an overcurrent protection circuit, which comprises: a second comparator circuit for comparing a voltage signal characterizing the load current with a second reference voltage and outputting a comparison result; a second control unit for determining whether the second control unit is turned on based on the comparison result, wherein the second control unit is turned on when the voltage signal characterizing the load current is less than the second reference voltage and turned off when the voltage signal characterizing the load current is greater than the second reference voltage; a fifth current mirror having a reference current terminal and a bias current terminal, the reference current terminal being coupled to a sixth current source and the bias current terminal being coupled to the second control unit; and a charging circuit having an input terminal and an output terminal, the input terminal being coupled to the supply voltage and the output terminal being coupled to the control terminal of the power transistor, wherein when the second control unit is turned off, the charging circuit is turned on, and the supply voltage charges the control terminal of the power transistor.

[0017] Optionally, the second comparator circuit includes: a sixth current mirror; a first differential circuit having a first input terminal, a second input terminal, a first output terminal, and a second output terminal, wherein the first input terminal is coupled to a third current source, and the second input terminal is coupled to a fifth current source; a seventh current mirror having a reference current terminal and a bias current terminal, wherein the reference current terminal is coupled to the first input terminal of the first differential circuit, and the bias current terminal is coupled to the bias current terminal of the sixth current mirror; an eighth current mirror having a reference current terminal and a bias current terminal, wherein the reference current terminal is coupled to the second input terminal of the first differential circuit, and the bias current terminal is coupled to the reference current terminal of the sixth current mirror; a nineteenth transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the third current source, the second terminal is coupled to a reference ground, and the control terminal is coupled to a load current; and a twentieth transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the fifth current source, the second terminal is coupled to a reference ground, and the control terminal is coupled to a second reference voltage.

[0018] Optionally, the second control unit includes a tenth transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the bias current terminal of the fifth current mirror, the second terminal is coupled to a reference ground, and the control terminal is coupled to the bias current terminal of the sixth current mirror.

[0019] Optionally, the charging circuit includes: a ninth transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to a supply voltage, the second terminal is coupled to the control terminal of the power transistor, and the control terminal is coupled to the first terminal of the tenth transistor.

[0020] Optionally, the low-dropout linear regulator further includes a short-circuit protection circuit, which includes: a second differential circuit having a first input terminal, a second input terminal, a first output terminal, and a second output terminal, wherein the first input terminal is coupled to a first voltage signal representing the load current, and the second input terminal is coupled to a third reference voltage; a twenty-fifth transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the first output terminal of the second differential circuit, the second terminal is coupled to a reference ground, and the control terminal is coupled to its first terminal; a twenty-sixth transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to the second output terminal of the second differential circuit, the second terminal is coupled to a reference ground, and the control terminal is coupled to its first terminal; and a twenty-seventh transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is coupled to a second voltage signal representing the load current, the second terminal is coupled to a reference ground, and the control terminal is coupled to the second output terminal of the second differential circuit.

[0021] Beneficial effects

[0022] This invention proposes a highly stable low-dropout linear regulator, comprising a power transistor, an error amplifier, and a compensation circuit. The power transistor outputs the load current. The error amplifier controls the conduction level of the power transistor based on the difference signal between the feedback voltage and a first reference voltage, thereby affecting the magnitude of the load current. The compensation circuit compensates for the difference signal according to the load condition. When the load is a Class I load, a current signal equal to the load current is compensated for the difference, performing a Class I correction on the voltage at the control terminal of the power transistor. When the load is a Class II load, a current signal that follows the load current is compensated for the difference, performing a Class II correction on the voltage at the control terminal of the power transistor. By setting different compensation values ​​according to different loads, the influence of different poles is reduced, thus enhancing the stability of the low-dropout linear regulator. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and, together with the description, serve to explain embodiments of the invention, but do not constitute a limitation thereof. In the drawings:

[0024] Figure 1 A structural diagram of a common low-dropout linear regulator is shown.

[0025] Figure 2 A structural diagram of a compensation circuit according to an embodiment of the present invention is shown;

[0026] Figure 3 A structural diagram of a power transistor protection circuit according to an embodiment of the present invention is shown;

[0027] Figure 4 A structural diagram of an overcurrent protection circuit and a short-circuit protection circuit according to an embodiment of the present invention is shown. Detailed Implementation

[0028] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0029] The description in this section pertains to only a few typical embodiments, and the present invention is not limited to the scope of the embodiments described. Combinations of different embodiments, substitution of some technical features in different embodiments, and substitution of similar or identical prior art with some technical features in the embodiments are also within the scope of the description and protection of the present invention.

[0030] The terms "coupled" or "connected" in this specification include both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a connection through an electrically conductive medium like a conductor, which may contain parasitic inductance or capacitance. It can also be a connection through intermediate circuits or components described in the embodiments of this specification. Indirect connections may also include connections through other active or passive devices that achieve the same or similar function, such as connections through switches, signal amplification circuits, follower circuits, or other circuits or components. "Multiple" or "more" indicates two or more.

[0031] In the loop control of a low-dropout linear regulator, poles can cause instability. One solution is zero-point compensation, which uses a compensation circuit to correct the voltage at the control terminal of the power transistor, thereby maintaining the stability of the low-dropout linear regulator.

[0032] like Figure 2 As shown, this invention provides a highly stable low-dropout linear regulator, including a power transistor (MP), an error amplifier (EA), and a compensation circuit 100. The input terminal of the power transistor is coupled to the supply voltage (Vin), and the output terminal generates an output voltage (Vout). The control terminal of the power transistor controls its conduction level, thereby controlling the output voltage value. The output voltage generates a feedback voltage based on feedback resistors (R1, R2). The feedback voltage and a first reference voltage (Vref1) are input to the first and second input terminals of the error amplifier, respectively. The error amplifier outputs the difference signal between the feedback voltage and the first reference voltage as the control terminal voltage of the power transistor. The compensation circuit 100 corrects the control terminal voltage of the power transistor. When the load is a Class I load, it compensates the difference signal with a current signal equal to the load current; when the load is a Class II load, it compensates the difference signal with a current signal that varies with the load current. Setting different compensation values ​​according to different loads enhances the stability of the low-dropout linear regulator.

[0033] The power transistor can be configured as a transistor, field-effect transistor, or insulated-gate bipolar transistor depending on the circuit. In this embodiment, the power transistor is a PMOS transistor, so the first input terminal and the second input terminal of the error amplifier are the non-inverting input terminal and the inverting input terminal, respectively. Alternatively, the power transistor can be configured as an NMOS transistor, in which case the first input terminal and the second input terminal of the error amplifier are the inverting input terminal and the non-inverting input terminal.

[0034] In one embodiment, one type of load is an ultra-light load, and the other type of load is a light load. Correspondingly, the compensation circuit 100 includes an ultra-light load compensation circuit 110 and a light load compensation circuit 120.

[0035] like Figure 2 As shown, the ultra-light load compensation circuit 110 includes a first comparison circuit and a first control unit. The first comparison circuit compares the load current with the reference current and outputs the comparison result. The first control unit determines whether to compensate the difference signal based on the comparison result. If the load current is less than the reference current, a current signal equal to the load current is compensated for the difference signal. Specifically, the first comparison circuit includes a first current source (I1) and a first current mirror (M37, M40). The first current mirror generates a reference current and copies the load current at the reference current terminal to the bias current terminal, so that the load current and the reference current are in the same path. Based on Hofkir's law, sampling is performed at the intersection of the load current and the reference current. The sampled current is compared with zero current to determine the magnitude of the load current and the reference current. The first control unit includes a second current mirror (M39, M40) and a thirty-eighth transistor (M38). The control terminal of the thirty-eighth transistor is coupled to the intersection mentioned above. When the reference current is greater than the load current, the drive current at the control terminal of the thirty-eighth transistor is in the inflow state, and the thirty-eighth transistor is turned on. When the reference current is less than the load current, the drive current at the control terminal of the thirty-eighth transistor is in the outflow state, and the thirty-eighth transistor is turned off. The input terminal of the thirty-eighth transistor is coupled to the control terminal of the power transistor. When the thirty-eighth transistor is turned on, it discharges to the control terminal of the power transistor. The second current mirror determines the magnitude of the discharge current. The second current mirror replicates the load current at the reference current terminal into the path of the thirty-eighth transistor. Therefore, under ultra-light load conditions, the ultra-light load compensation circuit 110 compensates the difference signal with a load current signal.

[0036] like Figure 2As shown, the light load compensation circuit 120 includes a third current mirror (M36, M30), a fourth current mirror (M28, M29), and a variable resistor circuit. The variable resistor circuit includes a thirty-second transistor (M32), a thirty-third transistor (M33), a thirty-fourth transistor (M34), and a thirty-fifth transistor (M35). These transistors operate in the variable resistance region. The third and fourth current mirrors replicate the load current to the control terminals of these transistors, causing the resistance value of the variable resistor circuit to change with the load current. The light load compensation circuit 120 also includes a thirty-first transistor (M31), which discharges current to the control terminal of the variable resistor circuit. The light load compensation circuit 120 also includes a compensation resistor (R11) and a compensation capacitor (C2), which optimize the compensation current signal. Therefore, under light load conditions, the light load compensation circuit 120 tracks changes in the load current and compensates the difference signal with a current signal that follows the load current change.

[0037] It is understandable that when the load current is less than the reference current, the light load compensation circuit 120 will be short-circuited, and when the load current is greater than the reference current, the ultra-light load compensation circuit 110 will be disconnected. Therefore, the threshold values ​​for ultra-light load and light load are determined by the set reference current value.

[0038] Because the error amplifier has internal gain, its output fluctuates greatly. To extend the lifespan of the power transistor, such as... Figure 3 As shown, the low-dropout linear regulator of the present invention also includes a power transistor protection circuit, which includes a first transistor (M1), a second transistor (M2), and a third transistor (M3). Thus, the control terminal of the power transistor is no longer directly coupled to the output terminal of the error amplifier. The first and second transistors discharge the control terminal of the power transistor, while the third transistor charges it. The output of the error amplifier controls the discharge current, so the conduction level of the power transistor is still controlled by the output of the error amplifier. Since there is a situation where the power transistor and the 40th transistor (M40) are simultaneously conducting, the current in the power transistor will be very large. To protect the power transistor, the low-dropout linear regulator also includes a sixth transistor (M6).

[0039] like Figure 4As shown, the low-dropout linear regulator also includes an overcurrent protection circuit 200, which includes a second comparator circuit, a second control unit, a fifth current mirror, and a charging circuit. The second comparator circuit includes a sixth current mirror (M13, M14), a first differential circuit (M15, M16), a seventh current mirror (M17, M22), an eighth current mirror (M18, M21), a nineteenth transistor (M19), and a twentieth transistor (M20). As can be seen, if the drive current of the source of the first differential circuit remains unchanged, the input current at the second input terminal (right side) of the first differential circuit is a fixed value, and therefore the output current at the second output terminal is also a fixed value. This fixed current is replicated to the bias current terminal of the sixth current mirror (in the same branch as M22) through the eighth and sixth current mirrors. The input current at the first input terminal (left side) of the first differential circuit is controlled by the control terminal of the nineteenth transistor. The control terminal of the nineteenth transistor is coupled to the load current (M5 and the power transistor form a current mirror). When the load current increases, the conduction degree of the nineteenth transistor decreases, thereby increasing the input current at the first input terminal of the first differential circuit and decreasing the output current at the first output terminal of the first differential circuit. This current is replicated to the bias current terminal of the seventh current mirror (in the same branch as M22) through the seventh current mirror. Based on Hofkir's law, the currents in the same branch can be compared. The second control unit includes the tenth transistor (M10). When the load current increases, the voltage at the control terminal of the tenth transistor increases. When the voltage at the control terminal reaches a critical value, the tenth transistor changes from being on to being off. Understandably, by adjusting the preset value of the second reference voltage (Vref2), the tenth transistor can be controlled to turn on when the load current voltage signal is less than the second reference voltage and turn off when the load current voltage signal is greater than the second reference voltage. The fifth current mirror (M11, M12) is used to provide a constant input current to the control terminal of the ninth transistor. The charging circuit includes the ninth transistor (M9). When the tenth transistor is on, the pull-down voltage at the control terminal of the ninth transistor is greater than the rising voltage, so the ninth transistor is in the off state. When the tenth transistor is off, the pull-down voltage disappears, the voltage at the control terminal of the ninth transistor rises, the ninth transistor turns on, the supply voltage charges the control terminal of the power transistor, the voltage at the control terminal of the power transistor quickly reaches the supply voltage, and the power transistor turns off. In summary, the function of the entire overcurrent protection circuit 200 is: to set the value of the second reference voltage, limit the maximum current value of the load current, and when the load current exceeds the maximum current value, the overcurrent protection circuit 200 turns off the power transistor, thereby playing the role of overcurrent protection.

[0040] like Figure 4As shown, the low-dropout linear regulator also includes a short-circuit protection circuit 300. This circuit includes a second differential circuit (M23, M24), a twenty-fifth transistor (M25), a twenty-sixth transistor (M26), and a twenty-seventh transistor (M27). First, the preset value of the third reference voltage (Vref3) is relatively small. When the circuit is operating normally, the input voltage at the first input terminal (left side) of the second differential circuit is relatively high. Therefore, the conduction degree of the twenty-third transistor (M23) is low, the conduction degree of the twenty-fourth transistor (M24) is high, and the input current of the twenty-seventh transistor is relatively large. When a short circuit occurs, the input voltage at the first input terminal (left side) of the second differential circuit becomes very low, the conduction degree of the twenty-third transistor increases, and the input current of the twenty-seventh transistor decreases. This causes a change in the control terminal voltage of the twenty-seventh transistor, and its conduction degree changes accordingly. Therefore, the voltage value between resistors R6 and R7 also changes. This voltage is used as the foldback voltage for short-circuit protection.

[0041] Those skilled in the art should know that the logic controls such as "high level" and "low level", "set" and "reset", "AND gate" and "OR gate", "non-inverting input" and "inverting input" in the logic control involved in the specification or drawings can be interchanged or changed, and the same function or purpose as the above embodiment can be achieved by adjusting the subsequent logic control.

[0042] The description and application of the present invention herein are illustrative and not intended to limit the scope of the invention to the embodiments described above. The effects or advantages described in the specification may not be apparent in actual experimental cases due to uncertainties in specific conditions or other factors, and such descriptions are not intended to limit the scope of the invention. Variations and modifications to the embodiments disclosed herein are possible, and various substitutions and equivalents of the components in the embodiments are well known to those skilled in the art. It should be understood by those skilled in the art that the invention can be implemented in other forms, structures, arrangements, proportions, and with other components, materials, and parts without departing from the spirit or essential characteristics of the invention. Other variations and modifications can be made to the embodiments disclosed herein without departing from the scope and spirit of the invention.

Claims

1. A highly stable low-dropout linear voltage regulator, characterized in that, The low-dropout linear regulator includes: Power transistor; An error amplifier has a first input terminal coupled to a feedback voltage and a second input terminal coupled to a first reference voltage. The error amplifier is used to control the conduction degree of the power transistor based on the difference signal between the feedback voltage and the first reference voltage. The compensation circuit is used to compensate the difference signal according to the load condition. When the load is a Class I load, the difference signal is compensated with a current signal equal to the load current. When the load is a Class II load, the difference signal is compensated with a current signal that follows the load current. The compensation circuit includes an ultra-light load compensation circuit, which includes: The first comparator circuit is used to compare the load current with the reference current and output the comparison result; The first control unit is used to determine whether to compensate the difference signal based on the comparison result. If the load current is less than the reference current, the difference signal is compensated with a current signal equal to the load current.

2. The low-dropout linear regulator as described in claim 1, characterized in that: The first type of load is an ultra-light load, and the second type of load is a light load.

3. The low-dropout linear regulator as described in claim 1, characterized in that, The first comparator circuit includes: The first current source is used to generate the reference current; The first current mirror has a reference current terminal and a bias current terminal. Its reference current terminal is coupled to the load current, and its bias current terminal is coupled to the output terminal of the first current source.

4. The low-dropout linear regulator as described in claim 1, characterized in that, The first control unit includes: The second current mirror has a reference current terminal and a bias current terminal, with the reference current terminal coupled to the load current. The thirty-eighth transistor has an input terminal, an output terminal, and a control terminal. Its input terminal is coupled to the output terminal of the error amplifier, its output terminal is coupled to the bias current terminal of the second current mirror, and its control terminal is coupled to the first current source. Its control terminal is used to determine whether the thirty-eighth transistor is turned on based on the comparison result between the load current and the reference current.

5. The low-dropout linear regulator as described in claim 1, characterized in that, The compensation circuit further includes a light-load compensation circuit, which includes: The third current mirror has a reference current terminal and a bias current terminal, with the reference current terminal coupled to the load current. The fourth current mirror has a reference current terminal and a bias current terminal, wherein the reference current terminal is coupled to the bias current terminal of the third current mirror. A variable resistor circuit has an input terminal, an output terminal, and a control terminal. Its input terminal is coupled to the output terminal of the error amplifier, its output terminal is coupled to a reference ground, and its control terminal is coupled to the bias current terminal of the fourth current mirror. The internal resistance value of the variable resistor circuit changes with the bias current value of the fourth current mirror.

6. The low-dropout linear regulator as described in claim 5, characterized in that, The variable resistor circuit includes: The thirty-second transistor has a first terminal, a second terminal, and a control terminal. Its first terminal is coupled to the load current, and its control terminal is coupled to the control terminal of the thirty-first transistor. The thirty-third transistor has a first terminal, a second terminal and a control terminal, wherein the first terminal is coupled to the second terminal of the thirty-second transistor and the control terminal is coupled to the control terminal of the thirty-first transistor. The 34th transistor has a first terminal, a second terminal and a control terminal, wherein the first terminal is coupled to the second terminal of the 33rd transistor and the control terminal is coupled to the control terminal of the 31st transistor. The thirty-fifth transistor has a first terminal, a second terminal, and a control terminal. Its first terminal is coupled to the second terminal of the thirty-fourth transistor, its second terminal is coupled to a reference ground, and its control terminal is coupled to the control terminal of the thirty-first transistor.

7. The low-dropout linear regulator as described in claim 1, characterized in that, The low-dropout linear regulator further includes an overcurrent protection circuit, which comprises: The second comparator circuit is used to compare the voltage signal characterizing the load current with the second reference voltage and output the comparison result. The second control unit is used to determine whether the second control unit is turned on based on the comparison result. The second control unit is turned on when the voltage signal representing the load current is less than the second reference voltage, and turned off when the voltage signal representing the load current is greater than the second reference voltage. The fifth current mirror has a reference current terminal and a bias current terminal. Its reference current terminal is coupled to the sixth current source, and its bias current terminal is coupled to the second control unit. The charging circuit has an input terminal and an output terminal. Its input terminal is coupled to the supply voltage, and its output terminal is coupled to the control terminal of the power transistor. When the second control unit is turned off, the charging circuit is turned on, and the supply voltage charges the control terminal of the power transistor.

8. The low-dropout linear regulator as described in claim 7, characterized in that, The second comparator circuit includes: Sixth current mirror; The first differential circuit has a first input terminal, a second input terminal, a first output terminal, and a second output terminal. Its first input terminal is coupled to a third current source, and its second input terminal is coupled to a fifth current source. The seventh current mirror has a reference current terminal and a bias current terminal. Its reference current terminal is coupled to the first input terminal of the first differential circuit, and its bias current terminal is coupled to the bias current terminal of the sixth current mirror. The eighth current mirror has a reference current terminal and a bias current terminal. Its reference current terminal is coupled to the second input terminal of the first differential circuit, and its bias current terminal is coupled to the reference current terminal of the sixth current mirror. The nineteenth transistor has a first terminal, a second terminal and a control terminal, wherein the first terminal is coupled to the third current source, the second terminal is coupled to a reference ground, and the control terminal is coupled to the load current. The twentieth transistor has a first terminal, a second terminal, and a control terminal. Its first terminal is coupled to the fifth current source, its second terminal is coupled to a reference ground, and its control terminal is coupled to a second reference voltage.

9. The low-dropout linear regulator as described in claim 8, characterized in that, The second control unit includes: The tenth transistor has a first terminal, a second terminal, and a control terminal. Its first terminal is coupled to the bias current terminal of the fifth current mirror, its second terminal is coupled to a reference ground, and its control terminal is coupled to the bias current terminal of the sixth current mirror.

10. The low-dropout linear regulator as described in claim 9, characterized in that, The charging circuit includes: The ninth transistor has a first terminal, a second terminal, and a control terminal. Its first terminal is coupled to the supply voltage, its second terminal is coupled to the control terminal of the power transistor, and its control terminal is coupled to the first terminal of the tenth transistor.

11. The low-dropout linear regulator as described in claim 1, characterized in that, The low-dropout linear regulator further includes a short-circuit protection circuit, which includes: The second differential circuit has a first input terminal, a second input terminal, a first output terminal and a second output terminal. Its first input terminal is coupled to a first voltage signal characterizing the load current, and its second input terminal is coupled to a third reference voltage. The 25th transistor has a first terminal, a second terminal and a control terminal, the first terminal being coupled to the first output terminal of the second differential circuit, the second terminal being coupled to a reference ground, and the control terminal being coupled to its first terminal. The 26th transistor has a first terminal, a second terminal and a control terminal, the first terminal being coupled to the second output terminal of the second differential circuit, the second terminal being coupled to a reference ground, and the control terminal being coupled to its first terminal. The 27th transistor has a first terminal, a second terminal, and a control terminal. Its first terminal is coupled to a second voltage signal representing the load current, its second terminal is coupled to a reference ground, and its control terminal is coupled to the second output terminal of the second differential circuit.

Images