Low dropout regulator

Abstract

The invention relates to a low dropout regulator. The low-dropout linear regulator comprises a low-dropout linear regulator module and a soft start module, the low-dropout linear voltage stabilizing module comprises a first adjusting tube and a first driving circuit, the first adjusting tube is connected between the power input end and the power output end, and a control electrode of the first adjusting tube is connected with the first driving circuit. The soft start module comprises a switching circuit and a ramp voltage generation circuit which are connected, and the switching circuit and the first driving circuit are located in the same branch; the ramp voltage generating circuit is used for outputting a ramp voltage signal to control the switching circuit to be switched on; and under the condition that the switching circuit is switched on, the first driving circuit controls the first adjusting tube to be switched on. The soft start module can control the low-dropout linear voltage regulator module to gradually build output voltage in the starting process, the overshoot phenomenon and surge current caused by too high output building speed in the starting process are avoided, and therefore the circuit safety of the low-dropout linear voltage regulator is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and particularly to a low dropout linear regulator. Background Art

[0002] As a commonly used power management chip, a low dropout linear regulator (LDO) has the advantages of simple structure, low cost, low noise, and simple peripheral circuit, and is widely used in many fields such as medical, computer, industrial infrastructure equipment, and portable products.

[0003] However, in the traditional low dropout linear regulator, the output establishment speed is too fast during the startup process, which often leads to overshoot of the output voltage and may bring surge risks to the subsequent connected system. In addition, when there is an output capacitor, the rapidly established output voltage will excite a large surge current, increasing the risk of overloading the power supply.

[0004] Therefore, the traditional low dropout linear regulator has the problem of low circuit safety. Summary of the Invention

[0005] Based on this, it is necessary to provide a low dropout linear regulator with high circuit safety.

[0006] In a first aspect, the present application provides a low dropout linear regulator, including: a low dropout linear voltage regulation module and a soft start module; the low dropout linear voltage regulation module includes a first adjustment transistor and a first drive circuit, a first pole of the first adjustment transistor is used to connect to a power input terminal, a second pole of the first adjustment transistor is used to connect to a power output terminal, and a control pole of the first adjustment transistor is connected to the first drive circuit;

[0007] The soft start module includes:

[0008] a switch circuit for connecting to the first drive circuit; the switch circuit and the first drive circuit are in the same branch;

[0009] a ramp voltage generation circuit connected to the switch circuit for outputting a ramp voltage signal to control the switch circuit to conduct; when the switch circuit conducts, the first drive circuit controls the first adjustment transistor to turn on.

[0010] In one embodiment, the low dropout linear voltage regulation module further includes a conversion circuit and a first sampling feedback circuit, the conversion circuit is connected to the first drive circuit and the first sampling feedback circuit, and the first sampling feedback circuit is connected to the power output terminal;

[0011] Among them, the first sampling feedback circuit is used to sample the output voltage of the power supply output terminal and output a first feedback voltage corresponding to the output voltage;

[0012] The conversion circuit is used to generate a comparison current according to the first feedback voltage and a first reference voltage when the first feedback voltage reaches a first preset voltage;

[0013] The first driving circuit is further used to control the voltage of the control electrode of the first adjustment transistor according to the comparison current to control the conduction state of the first adjustment transistor.

[0014] In one embodiment, the first driving circuit includes a first transistor and a second transistor; a first pole of the first transistor is used to connect to the power supply input terminal, a control electrode of the first transistor is connected to the conversion circuit, and a second pole of the first transistor is connected to the control electrode of the first adjustment transistor; the second pole of the first transistor is further connected to a first end of the switching circuit, a second end of the switching circuit is connected to a first pole of the second transistor, and a control electrode and a second pole of the second transistor are grounded.

[0015] In one embodiment, the conversion circuit includes a third transistor and a first feedback transistor; a first pole of the third transistor is used to connect to the power supply input terminal, a control electrode and a second pole of the third transistor are connected to the first driving circuit; the second pole of the third transistor is further connected to a first pole of the first feedback transistor, a control electrode of the first feedback transistor is connected to the first sampling feedback circuit, and a second pole of the first feedback transistor is grounded.

[0016] In one embodiment, the first sampling feedback circuit includes a first sampling resistor and a second sampling resistor; a first end of the first sampling resistor is connected to the power supply output terminal, and a second end of the first sampling resistor is grounded through the second sampling resistor; wherein, a common end where the first sampling resistor and the second sampling resistor are connected is connected to the conversion circuit.

[0017] In one embodiment, the ramp voltage generating circuit includes a current generating unit and a capacitor; a first end of the current generating unit is connected to the power supply input terminal, a second end of the current generating unit is connected to a first end of the capacitor, and a second end of the capacitor is grounded; wherein, the first end of the capacitor is further connected to a controlled end of the switching circuit.

[0018] In one embodiment, the current generating unit is a current source; the switching circuit includes a switching transistor; a control electrode of the switching transistor is connected to the first end of the capacitor, a first pole of the switching transistor serves as the first end of the switching circuit, and a second pole of the switching transistor serves as the second end of the switching circuit.

[0019] In one embodiment, the switching transistor is an NMOS transistor.

[0020] The above-mentioned low-dropout linear regulator includes a low-dropout linear voltage regulation module and a soft-start module. The soft-start module includes a switching circuit and a ramp voltage generation circuit. The switching circuit is connected to a branch of the drive circuit of the low-dropout linear voltage regulation module. The ramp voltage generation circuit can output a gradually changing ramp voltage signal to control the gradual conduction of the switching circuit, so that the drive circuit controls the gradual turn-on of the first adjustment transistor, thereby realizing the soft start of the low-dropout linear voltage regulation module. Thus, the soft-start module can control the low-dropout linear voltage regulation module to gradually establish the output voltage during the startup process, effectively avoiding the overshoot phenomenon caused by too fast output establishment speed during the startup process. At the same time, the generation of inrush current during the startup process is significantly reduced, thereby greatly improving the safety of the entire circuit.

[0021] In a second aspect, the present application provides a low-dropout linear regulator, including: a low-dropout linear voltage regulation module and a soft-start module; the low-dropout linear voltage regulation module includes a second adjustment transistor, an error comparison circuit, and a second drive circuit. The first pole of the second adjustment transistor is used to connect to the power input terminal, the second pole of the second adjustment transistor is used to connect to the power output terminal, the control pole of the second adjustment transistor is connected to the second drive circuit, and the second drive circuit is also connected to the error comparison circuit;

[0022] The soft-start module includes:

[0023] A switching circuit for connecting to the error comparison circuit, and the switching circuit and the error comparison circuit are in the same branch;

[0024] A ramp voltage generation circuit connected to the switching circuit for outputting a ramp voltage signal to control the conduction of the switching circuit; when the switching circuit is conducting, the error comparison circuit outputs an adjustment voltage, so that the second drive circuit controls the turn-on of the second adjustment transistor according to the adjustment voltage.

[0025] In one embodiment, the low-dropout linear voltage regulation module further includes a second sampling feedback circuit; the second sampling feedback circuit is connected to the power output terminal for sampling the output voltage of the power output terminal and outputting a second feedback voltage corresponding to the output voltage;

[0026] The error comparison circuit is further configured to obtain a feedback current according to the second feedback voltage when the second feedback voltage reaches a second preset voltage, and output the adjustment voltage according to a reference current and the feedback current.

[0027] In one embodiment, the error comparison circuit includes a fourth transistor and a second feedback transistor; a first pole of the fourth transistor is configured to connect to a power input terminal, and a control pole and a second pole of the fourth transistor are connected; a first pole of the second feedback transistor is connected to the second driving circuit, and a common terminal where the first pole of the second feedback transistor is connected to the second driving circuit is further configured to connect to the second pole of the fourth transistor, a control pole of the second feedback transistor is connected to the second sampling feedback circuit, and a second pole of the second feedback transistor is grounded;

[0028] Wherein, a first end of the switching circuit is connected to the power input terminal, and a second end of the switching circuit is connected to the first pole of the fourth transistor; alternatively, a first end of the switching circuit is connected to the second pole of the fourth transistor, and a second end of the switching circuit is connected to a common terminal where the first pole of the second feedback transistor is connected to the second driving circuit.

[0029] In one embodiment, the second driving circuit includes a fifth transistor and a sixth transistor; a first pole of the fifth transistor is configured to connect to the power input terminal, a control pole and a second pole of the fifth transistor are connected to a control pole of the second regulating transistor, and the second pole of the fifth transistor is further connected to a first pole of the sixth transistor; a control pole of the sixth transistor is connected to the error comparison circuit, and a second pole of the sixth transistor is grounded.

[0030] In one embodiment, the second sampling feedback circuit includes a third sampling resistor and a fourth sampling resistor; a first end of the third sampling resistor is connected to a power output terminal, and a second end of the third sampling resistor is grounded through the fourth sampling resistor; wherein, a common terminal where the third sampling resistor and the fourth sampling resistor are connected is connected to the error comparison circuit.

[0031] In one embodiment, the ramp voltage generating circuit includes a current generating unit and a capacitor; a first end of the current generating unit is connected to the power input terminal, a second end of the current generating unit is connected to a first end of the capacitor, and a second end of the capacitor is grounded; wherein, the first end of the capacitor is further connected to a controlled terminal of the switching circuit.

[0032] In one embodiment, the current generating unit is a current source; the switching circuit includes a switching tube; a control pole of the switching tube is connected to the first end of the capacitor, a first pole of the switching tube serves as the first end of the switching circuit, and a second pole of the switching tube serves as the second end of the switching circuit.

[0033] In one embodiment, the switching tube is an NMOS tube.

[0034] The above-mentioned low-dropout linear regulator includes a low-dropout linear voltage regulation module and a soft start module. The soft start module includes a switching circuit and a ramp voltage generation circuit. The switching circuit is connected to a branch of the error comparison circuit of the low-dropout linear voltage regulation module. The ramp voltage generation circuit can output a gradually changing ramp voltage signal to control the gradual conduction of the switching circuit, so that the second drive circuit controls the gradual turn-on of the second adjustment transistor, thereby realizing the soft start of the low-dropout linear voltage regulation module. Thus, the soft start module can control the gradual turn-on of the second adjustment transistor during startup, effectively avoiding the overshoot phenomenon caused by too fast output establishment speed during startup. At the same time, the generation of inrush current during startup is significantly reduced, thereby greatly improving the safety of the entire circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0036] Figure 1 It is a schematic diagram of the modules of a low-dropout linear regulator in an embodiment;

[0037] Figure 2 It is a schematic diagram of the circuit structure of a low-dropout linear regulator in an embodiment;

[0038] Figure 3 It is a schematic diagram of the circuit structure of a low-dropout linear regulator in another embodiment;

[0039] Figure 4 It is a schematic diagram of the circuit structure of a low-dropout linear regulator in yet another embodiment;

[0040] Figure 5 It is a schematic diagram of the circuit structure of a low-dropout linear regulator in yet another embodiment;

[0041] Figure 6 It is a schematic diagram of the circuit structure of a low-dropout linear regulator in yet another embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] To facilitate the understanding of the present application, the following will describe the present application more comprehensively with reference to the relevant drawings. Embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0044] It can be understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0045] It can be understood that for "connection" in the following embodiments, if there is transmission of electrical signals or data between the connected circuits, modules, units, etc., it should be understood as "electrical connection", "communication connection", etc.

[0046] It can be understood that "at least one" means one or more, and "a plurality" means two or more. "At least a part of an element" means a part or all of the element.

[0047] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprises / include" or "has" etc. specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the related listed items.

[0048] As described in the background art, there is a technical problem of low circuit safety in the low dropout linear regulator in the related art.

[0049] The inventors' research found that in the traditional low dropout linear regulator, the output establishment speed is too fast during the startup process, which often causes the output voltage overshoot (that is, the output voltage briefly exceeds the expected value before reaching the steady state, forming a peak higher than the expected value). Among them, "output establishment" can be understood as the process in which the output voltage reaches the set value from the initial state. If the time of this process is very short and the output voltage reaches or approaches the set value quickly and almost instantaneously, it is considered that "the output establishment speed is too fast".

[0050] The overshoot phenomenon of the output voltage may bring surge risks to the subsequent connected systems, which may cause system instability or damage. In addition, when an output capacitor is connected to the output terminal, the rapidly established output voltage will generate a large inrush current, subjecting itself to a large current impact and increasing the power overload risk. Therefore, in traditional low-dropout linear regulators, the output establishment speed during startup is too fast, resulting in low circuit safety.

[0051] Based on the above technical problems, after long-term research, the inventor proposed the low-dropout linear regulator according to the embodiments of the present invention, which includes a low-dropout linear voltage regulation module and a soft start module. Among them, the low-dropout linear voltage regulation module can convert the input power supply connected thereto into a stable output voltage while maintaining a small input-output voltage difference.

[0052] The soft start module includes a switch circuit and a ramp voltage generation circuit. The switch circuit is connected to the low-dropout linear voltage regulation module. The ramp voltage generation circuit can output a ramp voltage signal to control the switch circuit to gradually turn on, so that the drive circuit controls the adjustment tube to gradually turn on, thereby realizing the soft start of the low-dropout linear voltage regulation module. Thus, the output voltage of the low-dropout linear voltage regulation module can be smoothly established, and no large inrush current will appear in the circuit during the output establishment process, thereby improving circuit safety.

[0053] The above is the core idea of the present invention. Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0054] Figure 1 FIG. is a schematic structural diagram of a low-dropout linear regulator provided by an embodiment of the present invention. As Figure 1 shown, the low-dropout linear regulator includes a low-dropout linear voltage regulation module 100 and a soft start module 200.

[0055] The low-dropout linear voltage regulation module 100 is connected to the power input terminal (not shown in the figure), and is used to convert the input power supply connected to the power input terminal into a stable output voltage while maintaining a small input-output voltage difference (i.e., low dropout).

[0056] The soft start module 200 includes a ramp voltage generation circuit 210 and a switch circuit 220 connected to each other. The switch circuit 220 is connected to the low-dropout linear voltage regulation module 100.

[0057] The ramp voltage generation circuit 210 is used to output a ramp voltage signal to control the switch circuit 220 to turn on. During the process of the switch circuit 220 turning on, the low-dropout linear voltage regulation module 100 realizes soft start.

[0058] It is understandable that the ramp voltage signal is a voltage waveform that changes continuously and monotonically over time. The voltage magnitude can start from an initial low level value and increase at a certain rate (which can be constant or variable) over time until it reaches a preset high level value. It can also start from an initial high level value and decrease at a certain rate (which can be constant or variable) over time until it reaches a preset low level value.

[0059] After receiving the ramp voltage signal, the conduction state of the switching circuit 220 gradually changes with the change of the ramp voltage. Taking the example that the switching circuit 220 gradually conducts as the ramp voltage increases, when the ramp voltage is at the initial low level, the switching circuit 220 may be in an off state or a partially conducting state; as the ramp voltage rises, the conduction degree of the switching circuit 220 gradually increases until it reaches a fully conducting state.

[0060] During the process of the switching circuit 220 gradually conducting, the output voltage of the low dropout linear voltage regulator module 100 can be made to change smoothly, avoiding problems such as output voltage overshoot and inrush current generation during the startup process of the low dropout linear voltage regulator module 100, thereby improving the stability and safety of the circuit.

[0061] Among them, the structure of the low dropout linear voltage regulator module 100 can be designed according to specific circumstances. In some embodiments, as Figure 2 shown, the low dropout linear voltage regulator module 100 includes a first regulating transistor P1. The first pole of the first regulating transistor P1 is used to connect to the power input terminal to access the input power supply VCC. The second pole of the first regulating transistor P1 is used to connect to the power output terminal. When the voltage at the control pole of the first regulating transistor P1 changes, its conduction degree changes, thereby adjusting the output voltage VOUT.

[0062] The type of the first regulating transistor P1 can be selected according to specific circumstances. For example, the first regulating transistor P1 can be a PMOS (P-channel Metal Oxide Semiconductor) or an NMOS (N-channel Metal Oxide Semiconductor). Exemplarily, the first regulating transistor P1 is an enhancement-mode PMOS transistor. Among them, the gate of the PMOS transistor serves as the control pole, the source serves as the first pole, and the drain serves as the second pole.

[0063] The low dropout linear voltage regulator module 100 further includes a first drive circuit 110. The first drive circuit 110 is connected to the control electrode of the first regulating transistor P1, and the switching circuit 220 and the first drive circuit 110 are in the same branch (that is, the switching circuit 220 and the first drive circuit 110 are connected through the same current path). During the process of the switching circuit 220 gradually turning on, the first drive circuit 110 controls the voltage of the control electrode of the first regulating transistor P1 to gradually change, the first regulating transistor P1 gradually turns on, and the output voltage VOUT is stably established.

[0064] The above-mentioned low dropout linear voltage regulator includes a low dropout linear voltage regulator module 100 and a soft start module 200. The soft start module 200 includes a ramp voltage generating circuit 210 and a switching circuit 220. The switching circuit 220 is connected to the branch of the first drive circuit 110 of the low dropout linear voltage regulator module. The ramp voltage generating circuit 210 can output a gradually changing ramp voltage signal VSLOPE to control the switching circuit 220 to gradually turn on, so that the first drive circuit 110 controls the first regulating transistor P1 to gradually turn on, thereby realizing the soft start of the low dropout linear voltage regulator module 100. Thus, the soft start module 200 can control the low dropout linear voltage regulator module 100 to gradually establish the output voltage during the startup process, effectively avoiding the voltage overshoot phenomenon caused by too fast output establishment speed during the startup process, and at the same time significantly reducing the generation of inrush current during the startup process, thereby greatly improving the safety of the entire circuit.

[0065] In this embodiment, through the collaborative work of the ramp voltage generating circuit 210 and the switching circuit 220, the soft start function of the low dropout linear voltage regulator module 100 is realized. The circuit structure of the soft start module 200 is simple, which simplifies the overall circuit structure of the low dropout linear voltage regulator and is beneficial to circuit integration and cost control.

[0066] In some embodiments, the low dropout linear voltage regulator module 100 further includes a first sampling feedback circuit 120. The first sampling feedback circuit 120 is connected to the power supply output terminal, and is used to sample the output voltage VOUT of the power supply output terminal and output a first feedback voltage VFB1 corresponding to the output voltage VOUT to the conversion circuit 130.

[0067] Since fluctuations in the input power supply VCC or changes in the load may affect the output voltage VOUT, by sampling the output voltage VOUT and adjusting the subsequent output voltage VOUT according to the sampled first feedback voltage VFB1, the output voltage VOUT can be kept stable.

[0068] The low dropout linear voltage regulator module 100 further includes a conversion circuit 130, and the conversion circuit 130 is connected to the first sampling feedback circuit 120. The conversion circuit 130 is configured to generate a comparison current according to the first feedback voltage VFB1 and the first reference voltage when the first feedback voltage VFB1 reaches a first preset voltage.

[0069] Wherein, the first reference voltage can be generated by a separately provided reference source, and the reference source can provide a stable reference voltage, enabling the conversion circuit 130 to generate an accurate comparison current.

[0070] The first reference voltage can also be generated by the conversion circuit 130. In some embodiments, the conversion circuit 130 is configured to generate the first reference voltage, so that a separately provided reference source is not required, the circuit structure is simple, and it is beneficial to reduce the circuit cost and power consumption.

[0071] The conversion circuit 130 is further connected to the first driving circuit 110, and the first driving circuit 110 is configured to control the gate voltage VGATE of the first regulating transistor P1 according to the comparison current output by the conversion circuit 130, and further control the conduction state of the first regulating transistor P1.

[0072] During the soft start process, the switch circuit 220 gradually conducts, so that the gate voltage VGATE output by the first driving circuit 110 to the first regulating transistor P1 in the same branch gradually decreases, the first regulating transistor P1 gradually conducts, and the output voltage VOUT is gradually established. During this process, the first feedback voltage VFB1 is lower than the first preset voltage, and the conversion circuit 130 does not output a comparison current.

[0073] After the soft start is completed, the first feedback voltage VFB1 is greater than or equal to the first preset voltage, and the conversion circuit 130 generates a comparison current according to the first feedback voltage VFB1 and the first reference voltage. The first driving circuit 110 controls the gate voltage VGATE of the first regulating transistor P1 connected between the input voltage terminal and the output voltage terminal according to the comparison current, so as to realize the dynamic adjustment of the output voltage VOUT by controlling the conduction state of the first regulating transistor P1.

[0074] Wherein, the first reference voltage can be determined according to the target value of the output voltage VOUT. In some embodiments, the first reference voltage is equal to the first feedback voltage VFB1 output by the first sampling feedback circuit 120 when the output voltage VOUT is the target value. The first preset voltage can be less than the first reference voltage, and can be specifically set according to actual situations.

[0075] In the low dropout linear regulator of this embodiment, during the soft start process, the control voltage VGATE of the first regulating transistor P1 gradually changes, and the first regulating transistor P1 gradually conducts, avoiding the problems of voltage overshoot and inrush current caused by too fast output establishment speed, thereby improving the safety of the circuit. After the low dropout linear regulator starts, the output voltage VOUT is sampled in real time through the first sampling feedback circuit 120, and combined with the conversion circuit 130 and the first driving circuit 110, the closed-loop control of the output voltage VOUT is realized, thereby improving the stability of the output.

[0076] In some embodiments, the first driving circuit 110 includes a first transistor P2 and a second transistor DN1. The first pole of the first transistor P2 is used to connect to the power input terminal, the control pole of the first transistor P2 is connected to the conversion circuit 130, and the second pole of the first transistor P2 is connected to the control pole of the first regulating transistor P1. The second pole of the first transistor P2 is also connected to the first end of the switching circuit 220, the second end of the switching circuit 220 is connected to the first pole of the second transistor DN1, and the control pole and the second pole of the second transistor DN1 are grounded.

[0077] Among them, the types of the first transistor P2 and the second transistor DN1 can be selected according to specific situations. Exemplarily, the first transistor P2 is a PMOS transistor, and the second transistor DN1 is an NMOS transistor. Further, the first transistor P2 is an enhancement-mode PMOS transistor, and the second transistor DN1 is a depletion-mode NMOS transistor. Among them, the gate of the NMOS transistor is used as the control pole, the drain is used as the first pole, and the source is used as the second pole.

[0078] In this embodiment, the second transistor DN1 forms a current path. During the process of the switching circuit 220 gradually conducting, the current passing through the second transistor DN1 also gradually increases, so that the voltage VGATE of the gate of the first regulating transistor P1 gradually decreases, and the first regulating transistor P1 gradually conducts, realizing the soft start of the low dropout linear voltage regulation module 100 and improving the safety of the circuit.

[0079] In some embodiments, the conversion circuit 130 includes a third transistor P3 and a first feedback transistor N1. The first pole of the third transistor P3 is used to connect to the power input terminal, the control pole and the second pole of the third transistor P3 are connected to the control pole of the first transistor P2; the second pole of the third transistor P3 is also connected to the first pole of the first feedback transistor N1, the control pole of the first feedback transistor N2 is connected to the first sampling feedback circuit 120, and the second pole of the first feedback transistor N1 is grounded.

[0080] The types of the third transistor P3 and the first feedback transistor N1 can be selected according to specific situations. Exemplarily, the third transistor P3 is a PMOS transistor, and the first feedback transistor N1 is an NMOS transistor.

[0081] Among them, the third transistor P3 and the first transistor P2 are of the same type and size. The third transistor P3, the first transistor P2, and the first feedback transistor N1 form a current mirror circuit.

[0082] Specifically, the first preset voltage is the threshold voltage of the first feedback transistor N1. During the process of the first adjustment transistor P1 gradually turning on, the output voltage VOUT gradually increases, and the first feedback voltage VFB1 output by the first sampling feedback circuit 120 gradually increases. When the first feedback voltage VFB1 reaches the threshold voltage of the first feedback transistor N1, the first feedback transistor N1 turns on. After the first feedback transistor N1 turns on, the first feedback voltage VFB1 increases or decreases following the output voltage VOUT, causing the current of the first feedback transistor N1 to increase or decrease. At this time, the output current of the first transistor P2 of the current mirror circuit changes accordingly, thereby causing the control gate voltage VGATE of the first adjustment transistor P1 to change, adjusting the conduction state of the first adjustment transistor P1, and further adjusting the output voltage Vout to achieve circuit voltage stabilization.

[0083] In this embodiment, the structure of the conversion circuit 130 is simple, which reduces the circuit complexity of the low dropout linear voltage regulator module 100, and further reduces the overall cost of the circuit.

[0084] In some embodiments, the first sampling feedback circuit 120 includes a first sampling resistor RFB1 and a second sampling resistor RFB2. The first end of the first sampling resistor RFB1 is connected to the power output terminal, and the second end of the first sampling resistor RFB1 is grounded through the second sampling resistor RFB2. Among them, the common terminal where the first sampling resistor RFB1 and the second sampling resistor RFB2 are connected is connected to the conversion circuit 130, specifically to the control gate of the first feedback transistor N1 in the conversion circuit 130.

[0085] In this embodiment, the resistance values of the first sampling resistor RFB1 and the second sampling resistor RFB2 can be set according to specific situations. The first sampling resistor RFB1 and the second sampling resistor RFB2 are connected in series between the power output terminal and the ground terminal, and the first feedback voltage VFB1 is output after voltage division. The first sampling feedback circuit 120 adopts a voltage division structure, and the voltage division sampling result is accurate and reliable. The circuit structure is simple and easy to implement.

[0086] In some embodiments, as Figure 3 shown, the ramp voltage generation circuit 210 includes a current generation unit 211 and a capacitor CAP. The first end of the current generation unit 211 is connected to the power input terminal, the second end of the current generation unit 211 is connected to the first end of the capacitor CAP, and the second end of the capacitor CAP is grounded. Among them, the first end of the capacitor CAP is also connected to the controlled end of the switch circuit 220.

[0087] When an input power supply VCC is provided at the power input terminal, the current generation unit 211 in the ramp voltage generation circuit 210 outputs a current to the first terminal of the capacitor CAP. Since the second terminal of the capacitor CAP is grounded, a ramp voltage signal VSLOPE, that is, a voltage signal whose magnitude changes gradually over time, is generated at the first terminal of the capacitor CAP. The controlled terminal of the switch circuit 220 receives the ramp voltage signal VSLOPE and gradually conducts, thereby enabling the low dropout linear voltage regulator module 100 to soft start.

[0088] In this embodiment, by utilizing the charge and discharge characteristics of the capacitor, the ramp voltage signal VSLOPE is generated by the capacitor CAP and the current generation unit 211. In practical applications, according to actual scenarios such as different loads and input voltage conditions, the ramp voltage signal VSLOPE can be precisely regulated by adjusting the magnitude of the current output by the current generation unit 211, adjusting the parameters of the capacitor CAP, etc., so as to adapt to specific application requirements. Thereby improving the versatility and adaptability of the low dropout linear voltage regulator.

[0089] Among them, the current generation unit 211 can be designed according to specific circumstances. In some embodiments, the current generation unit 211 is a current source I1.

[0090] The current source I1 can stably provide the required current output, making the accuracy and reliability of the ramp voltage signal VSLOPE higher. During actual implementation, the voltage change slope of the ramp voltage signal VSLOPE can be adjusted by adjusting the parameters of the current source I1 and the capacitor CAP. Thus, by enabling the ramp voltage signal VSLOPE to rise or fall smoothly as expected, the conduction state of the switch circuit 220 can be made stable and reliable, thereby improving the reliability of the soft start.

[0091] It can be understood that in other embodiments, the current generation unit 211 can also select other types of current generating devices, such as those based on current mirror circuits, etc., thereby improving the flexibility of circuit design.

[0092] In some embodiments, the switch circuit 220 includes a switching transistor N2. The control electrode of the switching transistor N2 is connected to the first terminal of the capacitor CAP, the first pole of the switching transistor N2 serves as the first terminal of the switch circuit 220, and the second pole of the switching transistor N2 serves as the second terminal of the switch circuit 220.

[0093] Since the switching transistor has a high switching speed and a controllable switching state, in this embodiment, the switching transistor N2 is selected in the switch circuit 220, which can quickly respond to the ramp voltage signal VSLOPE generated by the capacitor CAP. As the ramp voltage signal VSLOPE gradually changes, the switching transistor N2 gradually conducts to achieve the soft start control of the low dropout linear voltage regulator module 100.

[0094] Among them, the first pole, the second pole, and the control pole of the switching transistor N2 need to be determined according to the type of the switching transistor N2. In some embodiments, the switching transistor N2 is an NMOS transistor, whose gate serves as the control pole, the drain serves as the first pole, and the source serves as the second pole.

[0095] Specifically, as the NMOS transistor serving as the switching transistor N2, the gate is connected to the first end of the capacitor CAP for receiving the ramp voltage signal VSLOPE generated by the capacitor CAP. As the ramp voltage signal VSLOPE gradually increases, the gate-source voltage difference of the NMOS transistor increases, causing it to gradually transition from the cut-off state to the conducting state, thereby realizing the soft-start function.

[0096] In this embodiment, the high switching speed of the NMOS transistor can quickly respond to the change of the ramp voltage signal VSLOPE, improving the response speed and stability of the circuit. At the same time, its low on-resistance characteristic helps to reduce the energy loss during the switching process and improve the efficiency of the entire circuit.

[0097] In other embodiments, the switching transistor N2 can also be a PMOS transistor, with the gate still serving as the control pole, the source serving as the first pole, and the drain serving as the second pole.

[0098] The gate of the PMOS transistor is also connected to the first end of the capacitor CAP for receiving the ramp voltage signal VSLOPE generated by the capacitor CAP. However, different from the NMOS transistor, since the PMOS transistor is a P-type device, its conducting state is negatively correlated with the gate-source voltage difference. Therefore, when the ramp voltage signal VSLOPE gradually decreases, the PMOS transistor gradually transitions from the cut-off state to the conducting state, and at this time, the ramp voltage signal VSLOPE needs to be a gradually decreasing voltage signal.

[0099] To better understand the above embodiments, the following will be explained in detail with an optional embodiment. Please refer to Figure 3 , in one embodiment, the low-dropout linear regulator includes a low-dropout linear voltage regulation module 100 and a soft-start module 200. The low-dropout linear voltage regulation module 100 includes a first regulating transistor P1, a first driving circuit 110, a first sampling feedback circuit 120, and a conversion circuit 130. Among them, the first driving circuit 110 includes a first transistor P2 and a second transistor DN1, the conversion circuit 130 includes a third transistor P3 and a first feedback transistor N1, and the first sampling feedback circuit 120 includes a first sampling resistor RFB1 and a second sampling resistor RFB2.

[0100] The soft start module 200 includes a ramp voltage generation circuit 210 and a switching circuit 220 connected to each other. The switching circuit 220 is connected between a first transistor P2 and a second transistor DN1. Among them, the ramp voltage generation circuit 210 includes a current source I1 and a capacitor CAP, and the switching circuit 220 includes a switching transistor N2, and the switching transistor N2 is an NMOS transistor.

[0101] Specifically, in the low dropout linear regulator module 100, the second transistor DN1 serves as a current source, and its output current serves as a reference current to determine the current in the branch where it is located. The types and sizes of the first transistor P2 and the third transistor P3 are equal. The voltage at the gate of the first feedback transistor N1 is the first feedback voltage VFB1. Since the output voltage , where RFB1 represents the resistance value of the first sampling resistor RFB1, RFB2 represents the resistance value of the second sampling resistor RFB2, and VFB represents the feedback voltage; therefore, when the current in the branch where the first feedback transistor N1 is located is used as the reference current, the gate voltage of the first feedback transistor N1 can be used as the first reference voltage. Furthermore, by reasonably setting the resistance values of the first sampling resistor RFB1 and the second sampling resistor RFB2, the required output voltage VOUT, that is, the target value of the output voltage VOUT, can be determined.

[0102] It can be understood that in the absence of the soft start module 200, since the first feedback transistor N1 will not turn on until the first feedback voltage VFB1 is greater than or equal to its threshold voltage, there will be no current in the channels of the first feedback transistor N1, the first transistor P2, and the third transistor P3, so the loop of the low dropout linear regulator module 100 will not turn on either. At this time, the current source formed by the second transistor DN1 pulls down the voltage VGATE at the gate of the first regulator P1, causing the first regulator P1 to turn on, and the output voltage VOUT will form an overshoot and cause a surge current at the same time.

[0103] In this embodiment, a soft-start module 200 is provided. At the initial stage of circuit startup, the current source I1 has not yet charged the capacitor CAP, the ramp voltage signal VSLOPE is 0V, and the switching transistor N2 is in the off state (at this time, the first feedback transistor N1 is also in the off state because the first feedback voltage VFB1 is not greater than or equal to its threshold voltage). Therefore, the gate voltage VGATE of the first regulating transistor P1 will not discharge, and the first regulating transistor P1 is in the off state. So, the output voltage VOUT will not be overcharged and no inrush current will be caused. Subsequently, the current source I1 charges the capacitor CAP, and the ramp voltage signal VSLOPE gradually ramps up. The smaller the current source I1 or the larger the capacitor CAP, the smaller the slope of the ramp voltage signal VSLOPE. By designing appropriate current source I1 and capacitor CAP, the ramp voltage signal VSLOPE rises slowly, so that the switching transistor N2 turns on slowly, the current flowing through the switching transistor N2 also increases slowly, the source voltage of the switching transistor N2 rises slowly, and the gate voltage VGATE of the first regulating transistor P1 discharges and decreases slowly. Therefore, the output voltage VOUT is established slowly without inrush current. Then, the ramp voltage signal VSLOPE continues to rise until the second transistor DN1 enters the saturation region. At this time, the current flowing through the switching transistor N2 reaches the maximum, which is the saturation region current of the second transistor DN1. This saturation region current I can be expressed as: , where VTH_DN1 represents the threshold voltage of the second transistor DN1, μn represents the mobility of electrons, and Cox represents the capacitance of the gate oxide layer.

[0104] At this time, the first feedback voltage VFB1 has exceeded the turn-on threshold of the first feedback transistor N1, and negative feedback intervenes in the operation, so that the output voltage VOUT will not rise without limit during the startup stage, but will ultimately be adjusted to the target value.

[0105] The above soft-start module 200 only uses the current source I1, the capacitor CAP, and the switching transistor N2. The circuit structure is very simple. While effectively realizing the soft-start function and suppressing inrush current, it reduces the area cost and maintains the low-cost advantage of the low-dropout linear regulator.

[0106] Figure 4 FIG. is a schematic structural diagram of another low-dropout linear regulator provided by an embodiment of the present invention. The low-dropout linear regulator includes a low-dropout linear voltage regulation module 100 and a soft-start module 200 as shown in Figure 1 the figure.

[0107] Among them, the low-dropout linear voltage regulator module 100 includes a second regulating transistor P5, a second driving circuit 140, and an error comparison circuit 150. The first pole of the second regulating transistor P5 is used to connect to the power input terminal to access the input power supply VCC. The second pole of the second regulating transistor P5 is used to connect to the power output terminal. The control pole of the second regulating transistor P5 is connected to the second driving circuit 140, and the second driving circuit 140 is also connected to the error comparison circuit 150.

[0108] When the control pole voltage VGATE2 of the second regulating transistor P5 changes, its conduction degree changes, thereby changing the output voltage VOUT. The type of the second regulating transistor P5 can be selected as an NMOS transistor or a PMOS transistor according to specific circumstances. Exemplarily, the second regulating transistor P5 is an enhancement-mode PMOS transistor. Among them, the gate of the PMOS transistor serves as the control pole, the source serves as the first pole, and the drain serves as the second pole. The error comparison circuit 150 and the second driving circuit 140 are used to provide the control pole voltage VGATE2 to the control pole of the second regulating transistor P5 to change the conduction state of the second regulating transistor P5.

[0109] The soft start module 200 includes a ramp voltage generation circuit 210 and a switch circuit 220 connected to each other, and the switch circuit 220 is connected to the low-dropout linear voltage regulator module 100. Specifically, the switch circuit 220 and the error comparison circuit 150 are in the same branch (that is, the switch circuit 220 and the error comparison circuit 150 are connected through the same current path), and the switch circuit 220 is also connected to the error comparison circuit 150.

[0110] Among them, the ramp voltage generation circuit 210 is used to output a ramp voltage signal to control the conduction of the switch circuit 220. During the conduction process of the switch circuit 220, the error comparison circuit 150 outputs an adjustment voltage VEAOUT, so that the second driving circuit 140 controls the second regulating transistor P5 to turn on according to the adjustment voltage VEAOUT, thereby enabling the low-dropout linear voltage regulator module 100 to start up softly.

[0111] During the soft start process, the ramp voltage signal gradually changes, causing the switch circuit 220 to gradually conduct, the error comparison circuit 150 to output a gradually changing adjustment voltage VEAOUT, and the second driving circuit 140 to control the control pole voltage VGATE2 of the second regulating transistor P5 to gradually change, so that the second regulating transistor P5 gradually turns on.

[0112] Since the output voltage VOUT gradually increases during the process of the second regulating transistor P5 gradually turning on, that is, the output voltage is steadily established, problems such as output voltage overshoot and inrush current generation during the startup process of the low-dropout linear voltage regulator module 100 can be avoided.

[0113] The above-mentioned low-dropout linear regulator includes a low-dropout linear voltage regulation module 100 and a soft start module 200. The soft start module 200 includes a ramp voltage generation circuit 210 and a switching circuit 220. The switching circuit 220 is connected to the branch of the error comparison circuit 150 of the low-dropout linear voltage regulation module 100. The ramp voltage generation circuit 210 can output a gradually changing ramp voltage signal to control the gradual conduction of the switching circuit 220, so that the second drive circuit 140 controls the gradual turn-on of the regulating transistor, thereby realizing the soft start of the low-dropout linear voltage regulation module 100. Thus, the soft start module 200 can control the gradual turn-on of the second regulating transistor P5 during startup, effectively avoiding the overshoot phenomenon caused by the too fast output establishment speed during startup. At the same time, the generation of inrush current during startup is significantly reduced, thereby greatly improving the safety of the entire circuit.

[0114] In this embodiment, through the collaborative work of the ramp voltage generation circuit 210 and the switching circuit 220, the soft start function of the low-dropout linear voltage regulation module 100 is realized. The structure of the soft start module is simple, which simplifies the overall circuit structure of the low-dropout linear regulator and is conducive to circuit integration and cost control.

[0115] In actual implementation, the low-dropout linear voltage regulation module further includes a second sampling feedback circuit 160. The second sampling feedback circuit 160 is connected to the power supply output terminal and the error comparison circuit 150. The second sampling feedback circuit 160 is used to sample the output voltage VOUT of the power supply output terminal and output a second feedback voltage VFB2 corresponding to the output voltage VOUT.

[0116] The error comparison circuit 150 is used to obtain a feedback current according to the second feedback voltage VFB2 when the second feedback voltage VFB2 reaches a second preset voltage, and output an adjustment voltage VEAOUT according to the reference current and the feedback current. Then, the second drive circuit 140 adjusts the control electrode voltage VGATE2 of the second regulating transistor P5 according to the adjustment voltage VEAOUT.

[0117] It should be noted that the error comparison circuit 150 is also used to generate a reference current. Thus, there is no need to separately set a reference source, significantly saving the circuit cost of the low-dropout linear regulator and reducing power consumption.

[0118] During the soft start process, although the output voltage VOUT gradually increases, the second feedback voltage VFB2 is lower than the second preset voltage, and the error comparison circuit 150 does not generate a feedback current.

[0119] After the soft start is completed, the second feedback voltage VFB2 is greater than or equal to the second preset voltage. The error comparison circuit 150 generates a reference current and a feedback current, and outputs an adjustment voltage VEAOUT according to the reference current and the feedback current. Further, the second drive circuit 140 controls the gate voltage VGATE2 of the second adjustment transistor P5 connected between the input voltage terminal and the output voltage terminal according to the adjustment voltage VEAOUT, so as to realize the dynamic adjustment of the output voltage VOUT by controlling the conduction state of the second adjustment transistor P5.

[0120] Among them, the reference current is the current corresponding to the second reference voltage. The second reference voltage is determined according to the target value of the output voltage VOUT. In actual implementation, the second reference voltage is equal to the second feedback voltage VFB2 output by the second sampling feedback circuit 160 when the output voltage VOUT is the target value. The second preset voltage can be less than the second reference voltage, and can be specifically set according to the actual situation.

[0121] In the low dropout linear regulator of this embodiment, during the soft start process, the gate voltage VGATE2 of the second adjustment transistor P5 gradually changes, and the second adjustment transistor P5 gradually conducts, avoiding the problems of voltage overshoot and inrush current caused by too fast output establishment speed, thus improving the safety of the circuit. After the low dropout linear regulator starts, the output voltage VOUT is sampled in real time through the second sampling feedback circuit 160, and the closed-loop control of the output voltage VOUT is realized by combining the error comparison circuit 150 and the second drive circuit 140, thereby improving the stability of the output.

[0122] In some embodiments, the second sampling feedback circuit 160 includes a third sampling resistor RFB3 and a fourth sampling resistor RFB4. The first end of the third sampling resistor RFB3 is connected to the power output terminal, and the second end of the third sampling resistor RFB3 is grounded through the fourth sampling resistor RFB4. Among them, the common end where the third sampling resistor RFB3 and the fourth sampling resistor RFB4 are connected is connected to the error comparison circuit 150.

[0123] In this embodiment, the resistance values of the third sampling resistor RFB3 and the fourth sampling resistor RFB4 can be set according to the specific situation. The third sampling resistor RFB3 and the fourth sampling resistor RFB4 are connected in series between the power output terminal and the ground terminal, and the second feedback voltage VFB2 is output after voltage division. The second sampling feedback circuit 160 adopts a voltage division structure, and the voltage division sampling result is accurate and reliable, and the circuit structure is simple and easy to implement.

[0124] In some embodiments, the error comparison circuit 150 includes a fourth transistor DN2 and a second feedback transistor N4. The first pole of the fourth transistor DN2 is used to connect to the power input terminal, and the control pole and the second pole of the fourth transistor DN2 are connected. The first pole of the second feedback transistor N4 is connected to the second drive circuit 140, and the common terminal where the first pole of the second feedback transistor N4 is connected to the second drive circuit 140 is also used to connect to the second pole of the fourth transistor DN2. The control pole of the second feedback transistor N4 is connected to the second sampling feedback circuit 160, and the second pole of the second feedback transistor N4 is grounded.

[0125] Among them, the types of the fourth transistor DN2 and the second feedback transistor N4 can be selected according to specific situations. Exemplarily, both the fourth transistor DN2 and the second feedback transistor N4 are NMOS transistors. Further, the fourth transistor DN2 is a depletion-type NMOS transistor, and the second feedback transistor N4 is an enhancement-type NMOS transistor.

[0126] In this embodiment, for the depletion-type fourth transistor DN2, after the gate and the source are short-circuited, a current source is formed, and the current generated by this current source is the reference current.

[0127] The drain of the second feedback transistor N4 is connected to the source of the fourth transistor DN2, and the source of the second feedback transistor N4 is grounded. When the current flowing through the second feedback transistor N4 is the reference current, the voltage Vgs between the gate and the source of the second feedback transistor N4 is the second reference voltage.

[0128] It can be understood that in practical applications, the voltage at the gate of the second feedback transistor N4 is the second feedback voltage VFB2. Since the output voltage , where, RFB3 represents the resistance value of the third sampling resistor RFB3, RFB4 represents the resistance value of the fourth sampling resistor RFB4, and VFB2 represents the second feedback voltage; therefore, the reference current and the second reference voltage of the branch where the error comparison circuit 150 is located can be determined according to the fourth transistor DN2. Furthermore, by reasonably setting the resistance values of the third sampling resistor RFB3 and the fourth sampling resistor RFB4, the required output voltage VOUT, that is, the target value, can be obtained. When the output voltage VOUT is the target value, the output current of the fourth transistor DN2 is the reference current.

[0129] The second preset voltage is the threshold voltage of the second feedback transistor N4. During the soft start process, the second feedback voltage VFB2 is less than the threshold voltage of the second feedback transistor N4, and the second feedback transistor N4 is not conducting.

[0130] After the low-dropout linear voltage regulator module 100 starts to operate, the second feedback voltage VFB2 is greater than or equal to the threshold voltage of the second feedback transistor N4, and the second feedback transistor N4 conducts. When the output voltage VOUT fluctuates, the second feedback voltage VFB2 fed back by the second sampling feedback circuit 160 changes accordingly, so that an adjusted voltage VEAOUT corresponding to the change can be obtained. Specifically, when the output voltage VOUT decreases, the second feedback voltage VFB2 decreases accordingly, and the current of the second feedback transistor N4 (i.e., the feedback current) decreases and is less than the reference current of the fourth transistor DN2. At this time, the error adjustment voltage VEAOUT increases. When the output voltage VOUT increases, the feedback voltage VFB increases, the current of the second feedback transistor N4 increases and is greater than the reference current of the fourth transistor DN2. At this time, the error adjustment voltage VEAOUT decreases.

[0131] In this embodiment, the fourth transistor DN2 generates a fixed reference current. At the same time, the second feedback transistor N4 generates a corresponding variable feedback current according to the received second feedback voltage VFB2, so that the adjusted voltage VEAOUT is obtained based on the feedback current and the reference current, enabling the second drive circuit 140 to dynamically control the second adjustment transistor P5 according to the adjusted voltage VEAOUT to achieve stable output of the circuit.

[0132] The fourth transistor DN2 and the second feedback transistor N4 in the error comparison circuit 150 realize the dual functions of determining the reference voltage and error comparison. The circuit structure is simple and the cost is low, which can effectively reduce the cost of the low-dropout linear voltage regulator.

[0133] The way the switch circuit 220 is connected to the branch where the error comparison circuit 150 is located is not unique. In some embodiments, the first end of the switch circuit 220 is connected to the power input terminal, and the second end of the switch circuit 220 is connected to the first pole of the fourth transistor DN2.

[0134] By connecting the switch circuit 220 between the power input terminal and the fourth transistor DN2, the switch circuit 220 can directly and effectively control the current path from the power input terminal to the fourth transistor DN2. Thus, during the soft start process, by gradually turning on the switch circuit 220, the magnitude of the current flowing into the error comparison circuit 150 can be precisely limited, enabling the low-dropout linear voltage regulator module 100 to start stably and the output voltage VOUT to be established smoothly. This connection method does not require adjustment of the structure of the error comparison circuit 150, and the error comparison circuit 150 can maintain its original function unchanged, which helps to maintain the circuit stability of the low-dropout linear voltage regulator module 100. Moreover, this connection method is relatively simple and clear, which not only reduces the design complexity but also helps to improve the overall reliability and maintainability of the circuit.

[0135] In other embodiments, such asFigure 5 As shown, the first terminal of the switching circuit 220 is connected to the second pole of the fourth transistor DN2, and the common terminal connected to the first pole of the second feedback transistor N4 and the second driving circuit 140 is connected to the second terminal of the switching circuit 220.

[0136] By disposing the switching circuit 220 between two transistors in the branch of the error comparison circuit 150, the output of the fourth transistor DN2 can be precisely controlled, which helps to achieve a smoother voltage transition during the soft start process. After the start is completed, according to actual needs, the switching circuit 220 can be used to finely adjust the current in the error comparison stage, thereby helping to improve the flexibility of the low dropout linear regulator.

[0137] In some embodiments, the second driving circuit 140 includes a fifth transistor P4 and a sixth transistor N3. The first pole of the fifth transistor P4 is used to connect to the power input terminal. The control pole and the second pole of the fifth transistor P4 are connected to the control pole of the second regulating transistor P5, and the second pole of the fifth transistor P4 is also connected to the first pole of the sixth transistor N3. The second pole of the sixth transistor N3 is grounded, and the control pole of the sixth transistor N3 is connected to the error comparison circuit 150. Specifically, the control pole of the sixth transistor N3 is connected to the first pole of the second feedback transistor N4.

[0138] The types of the fifth transistor P4 and the sixth transistor N3 can be selected according to specific circumstances. Exemplarily, the fifth transistor P4 is a PMOS transistor of the same type as the second regulating transistor P5, and the sixth transistor N3 is an NMOS transistor. Further, both the fifth transistor P4 and the sixth transistor N3 are enhancement-mode MOS transistors.

[0139] During the soft start process, when the regulated voltage VEAOUT gradually increases, that is, when the gate voltage of the sixth transistor N3 gradually increases, the conduction degree of the sixth transistor N3 gradually increases, causing the control pole voltage VGATE2 of the second regulating transistor P5 to gradually decrease, and the conduction degree of the second regulating transistor P5 to gradually increase, thereby causing the output voltage VOUT to gradually increase. Thus, problems such as voltage overshoot and inrush current caused by too fast output establishment speed are avoided, and the circuit structure is simple and the circuit cost is low.

[0140] After startup is completed, when the output voltage VOUT decreases, the adjustment voltage VEAOUT increases, and the conduction degree of the sixth transistor N3 increases, so that the control gate voltage VGATE2 of the second adjustment transistor P5 decreases, and then the output voltage VOUT increases. Conversely, if the second sampling voltage VFB2 is higher than the second reference voltage, the gate voltage of the sixth transistor N3 decreases, that is, the adjustment voltage VEAOUT decreases, and the control gate voltage VGATE2 of the second adjustment transistor P5 increases, and then the output voltage VOUT decreases. Thus, the purpose of stabilizing the output voltage VOUT is achieved, which helps to improve the output stability of the low dropout linear voltage regulator module 100.

[0141] In actual implementation, the fifth transistor P4 in the second driving circuit 140 can also be replaced by a current source, and the current source is used as the load of the sixth transistor N3. In some embodiments, devices such as buffers can also be added to the second driving circuit 140. Those skilled in the art can adjust the structure of the second driving circuit 140 according to actual needs, and this embodiment does not limit this.

[0142] In some embodiments, such as Figure 6 shown, the ramp voltage generation circuit 210 includes a current generation unit 211 and a capacitor CAP. The first end of the current generation unit 211 is connected to the power input terminal, the second end of the current generation unit 211 is connected to the first end of the capacitor CAP, and the second end of the capacitor CAP is grounded. Among them, the first end of the capacitor CAP is also connected to the controlled end of the switch circuit 220.

[0143] When the input power supply VCC is provided at the power input terminal, the current generation unit 211 in the ramp voltage generation circuit 210 outputs current to the first end of the capacitor CAP. Since the second end of the capacitor CAP is grounded, a ramp voltage signal VSLOPE is generated at the first end of the capacitor CAP, that is, a voltage signal whose magnitude changes gradually with time. The controlled end of the switch circuit 220 receives the ramp voltage signal VSLOPE and gradually conducts, thereby soft-starting the low dropout linear voltage regulator module 100.

[0144] In this embodiment, by utilizing the charge and discharge characteristics of the capacitor, the ramp voltage signal VSLOPE is generated through the capacitor CAP and the current generation unit 211. In practical applications, according to actual scenarios such as different loads and input voltage conditions, the ramp voltage signal VSLOPE can be precisely regulated by adjusting the magnitude of the current output by the current generation unit 211, adjusting the parameters of the capacitor CAP, etc., to meet specific application requirements. Thereby improving the versatility and adaptability of the low dropout linear voltage regulator.

[0145] Among them, the current generation unit 211 can be designed according to specific circumstances. In some embodiments, the current generation unit 211 is a current source I1.

[0146] The current source I1 can stably provide the required current output, making the accuracy and reliability of the ramp voltage signal VSLOPE higher. Thus, by making the ramp voltage signal VSLOPE rise or fall smoothly as expected, the conduction state of the switch circuit 220 can be made stable and reliable, thereby improving the reliability of soft start.

[0147] It can be understood that in other embodiments, the current generation unit 211 can also select other types of current generating devices, such as those based on current mirror circuits, etc., so as to improve the flexibility of circuit design.

[0148] In some embodiments, the switch circuit 220 includes a switching transistor N2. The control electrode of the switching transistor N2 is connected to the first end of the capacitor CAP. The first electrode of the switching transistor N2 serves as the first end of the switch circuit 220, and the second electrode of the switching transistor N2 serves as the second end of the switch circuit 220.

[0149] It can be understood, Figure 6 In the illustrated embodiment, the first electrode of the switching transistor N2 serves as the first end of the switch circuit 220 and is connected to the power input terminal; the second electrode of the switching transistor N2 serves as the second end of the switch circuit 220 and is connected to the first electrode of the fourth transistor DN2. In actual implementation, if, as Figure 5 shown, the switch circuit 220 is connected between two transistors of the error comparison circuit 150, then the first electrode of the switching transistor N2 is connected to the second electrode of the fourth transistor DN2, and the second electrode of the switching transistor N2 is connected to the common terminal where the first electrode of the second feedback transistor N4 and the second drive circuit 140 are connected.

[0150] Since the switching transistor has a high switching speed and a controllable switching state, in this embodiment, the switching transistor N2 is selected in the switch circuit 220, which can quickly respond to the ramp voltage signal VSLOPE generated by the capacitor CAP. As the ramp voltage signal VSLOPE gradually changes, the switching transistor N2 gradually conducts to achieve the soft start control of the low dropout linear voltage regulator module 100.

[0151] Among them, the first electrode, second electrode, and control electrode of the switching transistor N2 need to be determined according to the type of the switching transistor N2. In some embodiments, the switching transistor N2 is an NMOS transistor, its gate serves as the control electrode, its drain serves as the first electrode, and its source serves as the second electrode.

[0152] Specifically, for the NMOS transistor serving as the switching transistor N2, the gate is connected to the first end of the capacitor CAP to receive the ramp voltage signal VSLOPE generated by the capacitor CAP. As the ramp voltage signal VSLOPE gradually increases, the gate-source voltage difference of the NMOS transistor increases, causing it to gradually transition from the cut-off state to the conduction state, thereby realizing the soft start function.

[0153] In this embodiment, the high switching speed of the NMOS transistor can quickly respond to the change of the ramp voltage signal VSLOPE, improving the response speed and stability of the circuit. At the same time, its low on-resistance characteristic helps to reduce the energy loss during the switching process and improve the efficiency of the entire circuit.

[0154] In other embodiments, the switching transistor N2 can also be a PMOS transistor. The gate still serves as the control electrode, the source serves as the first electrode, and the drain serves as the second electrode.

[0155] The gate of the PMOS transistor is also connected to the first end of the capacitor CAP to receive the ramp voltage signal VSLOPE generated by the capacitor CAP. However, different from the NMOS transistor, since the PMOS transistor is a P-type device, its conduction state is negatively correlated with the gate-source voltage difference. Therefore, when the ramp voltage signal VSLOPE gradually decreases, the PMOS transistor gradually transitions from the cut-off state to the conduction state. At this time, the ramp voltage signal VSLOPE needs to be a gradually decreasing voltage signal.

[0156] To better understand the above embodiments, the following will be explained in detail with an optional embodiment. Please refer to Figure 6 , in one embodiment, the low dropout linear regulator includes a low dropout linear voltage regulation module 100 and a soft start module 200. The low dropout linear voltage regulation module 100 includes a second regulating transistor P5, a second sampling feedback circuit 160, an error comparison circuit 150, and a second driving circuit 140. Among them, the second sampling feedback circuit 160 includes a third sampling resistor RFB3 and a fourth sampling resistor RFB4; the error comparison circuit 150 includes a fourth transistor DN2 and a second feedback transistor N4; the second driving circuit 140 includes a fifth transistor P4 and a sixth transistor N3.

[0157] The soft start module 200 includes a connected ramp voltage generation circuit 210 and a switching circuit 220. The switching circuit 220 is connected between the first transistor P2 and the second transistor DN1. Among them, the ramp voltage generation circuit 210 includes a current source I1 and a capacitor CAP, and the switching circuit 220 includes a switching transistor N2, and the switching transistor N2 is an NMOS transistor.

[0158] Specifically, in the low dropout linear voltage regulation module 100, the current-consuming transistor (the fourth transistor DN2) can determine the current of the error comparison circuit 150 branch, and then determine the gate voltage of the second feedback transistor N4. Then, by reasonably setting the third sampling resistor RFB3 and the fourth sampling resistor RFB4, the expected output voltage VOUT can be obtained.

[0159] It can be understood that in the absence of the soft start module 200, since the second feedback transistor N4 will not turn on until the second feedback voltage VFB2 is greater than or equal to its threshold voltage, the current source formed by the fourth transistor DN2 will quickly raise the gate voltage of the sixth transistor N3 at this time, and the sixth transistor N3 will quickly turn on. After the sixth transistor N3 turns on, it will quickly pull down the control voltage VGATE2 of the second regulator P5, causing the power transistor second regulator P5 to quickly turn on, and the output voltage VOUT may form an overshoot and cause inrush current at the same time.

[0160] In this embodiment, a soft start module 200 is provided, and the soft start module 200 is only composed of a current source I1, a capacitor CAP, and a switching transistor N2. At the initial stage of circuit startup, the current source I1 has not been able to charge the capacitor CAP yet, the ramp voltage signal VSLOPE is 0V, and the switching transistor N2 is in the off state. At this time, the second feedback transistor N4 is also in the off state because the second feedback voltage VFB1 has not been greater than or equal to its threshold voltage, so the adjustment voltage VEAOUT will not be charged, then the sixth transistor N3 will not turn on, the control voltage VGATE2 of the second regulator P5 will be raised, and the second regulator P5 will be turned off, so the output voltage VOUT will not have overcharge and will not cause inrush current. Subsequently, the current source I1 charges the capacitor CAP, and the voltage of the ramp voltage signal VSLOPE gradually climbs. The smaller the current source I1 or the larger the capacitor CAP, the smaller the slope of the ramp voltage signal VSLOPE. Design a suitable current source I1 and capacitor CAP to make the ramp voltage signal VSLOPE rise slowly, so that the switching transistor N2 turns on slowly, the current flowing through the switching transistor N2 will also increase slowly, the source voltage of the switching transistor N2 and the adjustment voltage VEAOUT will rise slowly, then the sixth transistor N3 turns on slowly, and the control voltage VGATE2 of the second regulator P5 discharges and decreases slowly, so the output VOUT is established slowly and there will be no inrush current.

[0161] Subsequently, the ramp voltage signal VSLOPE continues to rise until the fourth transistor DN2 enters the saturation region. At this time, the current flowing through the switching transistor N2 reaches the maximum, which is the saturation region current of the fourth transistor DN2. This saturation region current I2 is expressed as: , where VTH_DN2 represents the threshold voltage of the fourth transistor DN2, μn represents the mobility of electrons, and Cox represents the capacitance of the gate oxide layer. At this time, the second feedback voltage VFB2 has exceeded the turn-on threshold of the second feedback transistor N4, and negative feedback intervenes in the work, so that the output voltage VOUT will not rise without limit during the startup stage, but will ultimately be adjusted to the target value.

[0162] The above-mentioned soft start module 200 only uses the current source I1, the capacitor CAP and the switching transistor N2. The circuit structure is very simple. While effectively realizing the soft start function and suppressing the inrush current, it reduces the area cost and maintains the low-cost advantage of the low dropout linear regulator.

[0163] In the description of this specification, the description with reference to terms such as "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or features described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0164] The technical features of the above-mentioned embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0165] The above-mentioned embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A low voltage dropout linear regulator, characterized in that: include: A low voltage difference linear voltage regulator module and a soft start module; the low voltage difference linear voltage regulator module comprises a first adjustment tube and a first drive circuit, the first electrode of the first adjustment tube is used to connect to the power input end, the second electrode of the first adjustment tube is used to connect to the power output end, and the control electrode of the first adjustment tube is connected to the first drive circuit; The soft start module comprises: A switch circuit, used to connect the first drive circuit; the switch circuit and the first drive circuit are in the same branch; The ramp voltage generating circuit is connected to the switch circuit and is used to output a ramp voltage signal to control the switch circuit to be turned on; when the switch circuit is turned on, the first drive circuit controls the first adjustment tube to be turned on.

2. The low voltage dropout linear regulator according to claim 1, characterized in that: The low voltage difference linear voltage regulator module further includes a conversion circuit and a first sampling feedback circuit; the conversion circuit is connected to the first driving circuit and the first sampling feedback circuit, and the first sampling feedback circuit is connected to the power supply output end; Wherein, the first sampling feedback circuit is used to sample the output voltage of the output end of the power supply and output a first feedback voltage corresponding to the output voltage; The conversion circuit is configured to generate a comparison current according to the first feedback voltage and a first reference voltage when the first feedback voltage reaches a first preset voltage; The first driving circuit is further used to control the voltage of the control electrode of the first adjusting tube according to the comparison current, so as to control the conduction state of the first adjusting tube.

3. The low voltage dropout linear regulator according to claim 2, characterized in that: The first driving circuit includes a first transistor and a second transistor; the first electrode of the first transistor is used to connect to the power input terminal, the control electrode of the first transistor is connected to the conversion circuit, and the second electrode of the first transistor is connected to the control electrode of the first adjustment tube; the second electrode of the first transistor is also connected to the first end of the switching circuit, the second end of the switching circuit is connected to the first electrode of the second transistor, and the control electrode and the second electrode of the second transistor are grounded.

4. The low voltage dropout linear regulator according to claim 2, characterized in that: The conversion circuit includes a third transistor and a first feedback transistor; the first electrode of the third transistor is used to connect to the power input terminal, the control electrode and the second electrode of the third transistor are connected to the first drive circuit; the second electrode of the third transistor is also connected to the first electrode of the first feedback transistor, the control electrode of the first feedback transistor is connected to the first sampling feedback circuit, and the second electrode of the first feedback transistor is grounded.

5. The low voltage dropout linear regulator according to claim 2, characterized in that: The first sampling feedback circuit includes a first sampling resistor and a second sampling resistor; a first end of the first sampling resistor is connected to a power supply output end, and a second end of the first sampling resistor is grounded through the second sampling resistor; wherein a common end where the first sampling resistor and the second sampling resistor are connected is connected to the conversion circuit.

6. A low voltage dropout linear regulator, characterized in that: include: A low voltage difference linear voltage regulator module and a soft start module; the low voltage difference linear voltage regulator module comprises a second adjustment tube, an error comparison circuit and a second drive circuit, the first electrode of the second adjustment tube is used to connect to the power input end, the second electrode of the second adjustment tube is used to connect to the power output end, the control electrode of the second adjustment tube is connected to the second drive circuit, and the second drive circuit is also connected to the error comparison circuit; The soft start module comprises: A switch circuit, used for connecting the error comparison circuit, wherein the switch circuit and the error comparison circuit are in the same branch; The ramp voltage generating circuit is connected to the switch circuit and is used to output a ramp voltage signal to control the switch circuit to be turned on; when the switch circuit is turned on, the error comparison circuit outputs an adjustment voltage so that the second drive circuit controls the second adjustment tube to be turned on according to the adjustment voltage.

7. The low voltage dropout linear regulator according to claim 6, characterized in that: The low voltage difference linear voltage regulator module further includes a second sampling feedback circuit; the second sampling feedback circuit is connected to the power supply output terminal, and is used to sample the output voltage of the power supply output terminal, and output a second feedback voltage corresponding to the output voltage; The error comparison circuit is further configured to obtain a feedback current according to the second feedback voltage when the second feedback voltage reaches a second preset voltage, and output the adjustment voltage according to a reference current and the feedback current.

8. The low voltage dropout linear regulator according to claim 7, characterized in that: The error comparison circuit includes a fourth transistor and a second feedback transistor; the first electrode of the fourth transistor is used to connect to the power input terminal, and the control electrode of the fourth transistor is connected to the second electrode; the first electrode of the second feedback transistor is connected to the second drive circuit, and the common end connected to the first electrode of the second feedback transistor and the second drive circuit is also used to connect to the second electrode of the fourth transistor, the control electrode of the second feedback transistor is connected to the second sampling feedback circuit, and the second electrode of the second feedback transistor is grounded; In which, the first end of the switching circuit is connected to the power input end, and the second end of the switching circuit is connected to the first electrode of the fourth transistor; or, the first end of the switching circuit is connected to the second electrode of the fourth transistor, and the second end of the switching circuit is connected to the common end connected to the first electrode of the second feedback transistor and the second drive circuit.

9. The low voltage dropout linear regulator according to claim 7, characterized in that: The second driving circuit includes a fifth transistor and a sixth transistor; the first electrode of the fifth transistor is used to connect to the power input terminal, the control electrode and the second electrode of the fifth transistor are connected to the control electrode of the second adjustment tube, and the second electrode of the fifth transistor is also connected to the first electrode of the sixth transistor; the control electrode of the sixth transistor is connected to the error comparison circuit, and the second electrode of the sixth transistor is grounded.

10. The low voltage dropout linear regulator according to claim 7, characterized in that: The second sampling feedback circuit includes a third sampling resistor and a fourth sampling resistor; a first end of the third sampling resistor is connected to a power supply output end, and a second end of the third sampling resistor is grounded through the fourth sampling resistor; wherein a common end of the third sampling resistor and the fourth sampling resistor is connected to the error comparison circuit.

11. The low voltage dropout linear regulator according to any one of claims 1 to 5, or the low voltage dropout linear regulator according to any one of claims 6 to 10, characterized in that: The ramp voltage generating circuit includes a current generating unit and a capacitor; the first end of the current generating unit is connected to the power input end, the second end of the current generating unit is connected to the first end of the capacitor, and the second end of the capacitor is grounded; wherein the first end of the capacitor is also connected to the controlled end of the switching circuit.

12. The low voltage dropout linear regulator according to claim 11, characterized in that: The current generating unit is a current source; the switching circuit includes a switching tube; the control electrode of the switching tube is connected to the first end of the capacitor, the first electrode of the switching tube serves as the first end of the switching circuit, and the second electrode of the switching tube serves as the second end of the switching circuit.

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