Low-dropout linear voltage stabilizing circuit, control method and low-dropout linear voltage regulator

Abstract

The invention discloses a low-dropout linear voltage stabilizing circuit, a control method and a low-dropout linear voltage regulator. The low-dropout linear voltage stabilizing circuit comprises a voltage sampling module which is connected with the input end of the low-dropout linear voltage stabilizing circuit and used for sampling the voltage of the input end of the low-dropout linear voltage stabilizing circuit and outputting a first voltage; the first input end of the voltage modulation module is connected with the output end of the voltage sampling module, the second input end of the voltage modulation module is connected with a first preset voltage, and the voltage modulation module is used for reducing the reference voltage when the first voltage is smaller than the first preset voltage; when the first voltage is greater than a first preset voltage, a constant reference voltage is generated; the first input end of the voltage output module is connected with the output end of the voltage modulation module, the second input end of the voltage output module is connected with the input end of the low-dropout linear voltage stabilizing circuit, and the voltage output module is used for performing voltage output according to the reference voltage. According to the embodiment of the invention, the voltage output effect is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of voltage stabilizing circuit, and particularly relates to a low-dropout linear voltage stabilizing circuit, a control method and a low-dropout linear voltage stabilizer. BACKGROUND

[0002] The low-dropout linear voltage stabilizer can provide a voltage to face different power supply application scenarios. With the continuous development of new energy vehicles, the low-dropout linear voltage stabilizer with a wide input range is widely used in new energy vehicles to face different voltage application requirements of automobile electronics.

[0003] However, when the input voltage of the low-dropout linear voltage stabilizer is low, the loop gain of the low-dropout linear voltage stabilizer will rapidly decrease and lose the loop regulation capability. Therefore, the existing low-dropout linear voltage stabilizer has poor voltage output effect. SUMMARY

[0004] The present application provides a low-dropout linear voltage stabilizing circuit, a control method and a low-dropout linear voltage stabilizer to improve the output effect of the voltage.

[0005] According to an aspect of the present application, a low-dropout linear voltage stabilizing circuit is provided, comprising:

[0006] a voltage sampling module connected to the input end of the low-dropout linear voltage stabilizing circuit, configured to sample the voltage of the input end of the low-dropout linear voltage stabilizing circuit and output a first voltage;

[0007] a voltage modulation module, a first input end of the voltage modulation module being connected to an output end of the voltage sampling module, a second input end of the voltage modulation module being connected to a first preset voltage, the voltage modulation module being configured to reduce a reference voltage when the first voltage is less than the first preset voltage, and generate a constant reference voltage when the first voltage is greater than the first preset voltage;

[0008] a voltage output module, a first input end of the voltage output module being connected to an output end of the voltage modulation module, a second input end of the voltage output module being connected to the input end of the low-dropout linear voltage stabilizing circuit, the voltage output module being configured to perform voltage output according to the reference voltage.

[0009] Optionally, the voltage modulation module comprises a current shunt unit and a voltage generation unit.

[0010] a first end of the current shunt unit being connected to the input end of the low-dropout linear voltage stabilizing circuit, a second end of the current shunt unit being connected to a ground end, a third end of the current shunt unit being connected to the first preset voltage, and a fourth end of the current shunt unit being connected to the output end of the voltage sampling module;

[0011] The first end of the voltage generating unit is connected with the input end of the low dropout linear voltage stabilizing circuit, the second end of the voltage generating unit is connected with the ground end, and the third end of the voltage generating unit is connected with the fifth end of the current shunt unit; the third end of the voltage generating unit is also connected with the first input end of the voltage output module, and the voltage generating unit is used for generating the reference voltage.

[0012] The current shunt unit is used for shunting the current of the voltage generating unit according to the sizes of the first preset voltage and the first voltage, so as to adjust the reference voltage.

[0013] Optionally, the voltage generating unit comprises a second current source and a first resistor.

[0014] The first end of the second current source is connected with the input end of the low dropout linear voltage stabilizing circuit, the second end of the second current source is connected with the fifth end of the current shunt unit, and the second end of the second current source is also connected with the first end of the first resistor; the second end of the first resistor is connected with the ground end; and the first resistor is used for generating the reference voltage.

[0015] Optionally, the current shunt unit comprises a first current source, a first branch, a second branch and a third branch.

[0016] The first end of the first current source is connected with the input end of the low dropout linear voltage stabilizing circuit, the second end of the first current source is connected with the first end of the first branch, and the second end of the first current source is also connected with the first end of the second branch; the second ends of the first branch and the second branch are connected with the ground end.

[0017] The third end of the first branch is connected with the first preset voltage, and the third end of the second branch is connected with the output end of the voltage sampling module; the first branch and the second branch are used for conducting or turning off according to the sizes of the first preset voltage and the first voltage.

[0018] The first end of the third branch is connected with the third end of the voltage generating unit, the second end of the third branch is connected with the fourth end of the second branch, and the third end of the third branch is connected with the ground end; and the third branch is used for mirroring the current of the second branch.

[0019] Optionally, the first branch comprises a first transistor, a second transistor, a third transistor and a second resistor.

[0020] The first end of the first transistor is connected with the second end of the first current source, the second end of the first transistor is connected with the first end of the second resistor, and the control end of the first transistor is connected with the first preset voltage.

[0021] The first end of the second transistor is connected with the second end of the second resistor, the second end of the second transistor is connected with the first end of the third transistor, and the control end of the second transistor is connected with the first end of the second resistor;

[0022] The second end of the third transistor is connected with a ground end, and the control end of the third transistor is connected with the second end of the second resistor.

[0023] The second branch comprises a fourth transistor, a fifth transistor, a sixth transistor and a third resistor.

[0024] The first end of the fourth transistor is connected with the second end of the first current source, the second end of the fourth transistor is connected with the first end of the third resistor, and the control end of the fourth transistor is connected with the output end of the voltage sampling module.

[0025] The first end of the fifth transistor is connected with the second end of the third resistor, the second end of the fifth transistor is connected with the first end of the sixth transistor, and the control end of the fifth transistor is connected with the first end of the third resistor.

[0026] The second end of the sixth transistor is connected with a ground end, and the control end of the sixth transistor is connected with the second end of the third resistor.

[0027] The third branch comprises a seventh transistor and an eighth transistor.

[0028] The first end of the seventh transistor is connected with the third end of the voltage generation unit, the second end of the seventh transistor is connected with the first end of the eighth transistor, and the control end of the seventh transistor is connected with the control end of the fifth transistor.

[0029] The second end of the eighth transistor is connected with a ground end, and the control end of the eighth transistor is connected with the control end of the sixth transistor.

[0030] Optionally, the voltage sampling module comprises a ninth transistor, a tenth transistor, a fourth resistor and a fifth resistor.

[0031] The first end of the fourth resistor is connected with the input end of the low-dropout linear voltage stabilizing circuit, the second end of the fourth resistor is connected with the first end of the fifth resistor, and the second end of the fifth resistor is connected with a ground end.

[0032] The first end of the ninth transistor is connected with the first input end of the voltage modulation module, the second end of the ninth transistor is connected with the first end of the fifth resistor, and the control end of the ninth transistor is connected with the first end of the tenth transistor.

[0033] The second end of the tenth transistor is connected with the first end of the fifth resistor, and the first end of the tenth transistor is also connected with the control end of the tenth transistor.

[0034] Optionally, the voltage output module comprises an error amplifier, an eleventh transistor, a sixth resistor and a seventh resistor.

[0035] The positive input end of the error amplifier is connected with the output end of the voltage modulation module, and the negative input end of the error amplifier is connected with the first end of the seventh resistor.

[0036] The first end of the eleventh transistor is connected with the input end of the low-dropout linear regulator, the second end of the eleventh transistor is connected with the first end of the sixth resistor, and the second end of the eleventh transistor serves as the output end of the voltage output module; the second end of the sixth resistor is connected with the first end of the seventh resistor, and the second end of the seventh resistor is connected with the ground end.

[0037] According to another aspect of the present application, a control method of a low-dropout linear regulator is provided, which can be applied to the low-dropout linear regulator provided in any of the embodiments of the present application; the control method of the low-dropout linear regulator comprises:

[0038] sampling the voltage at the input end of the low-dropout linear regulator by a voltage sampling module, and generating a first voltage according to the voltage at the input end of the low-dropout linear regulator;

[0039] acquiring the first voltage and a first preset voltage by a voltage modulation module, and generating a reference voltage according to the first voltage and the first preset voltage;

[0040] acquiring the reference voltage by a voltage output module, and outputting the voltage according to the reference voltage.

[0041] Optionally, the generating of the reference voltage according to the first voltage and the first preset voltage comprises:

[0042] when the first voltage is less than the first preset voltage, the second branch and the third branch are turned on, the third branch shunts the current of the voltage generation unit, and the reference voltage is reduced;

[0043] when the first voltage is greater than the first preset voltage, the first branch is turned on, and the reference voltage remains a constant value.

[0044] According to another aspect of the present application, a low-dropout linear regulator is provided, which comprises the low-dropout linear regulator provided in any of the embodiments of the present application.

[0045] The technical scheme provided by the embodiment of the present application can sample the voltage of the input end of the low-dropout linear voltage stabilizing circuit through the voltage sampling module, the voltage modulation module generates reference voltages of different sizes according to voltages of different sizes, so that the voltage output module can adjust the output voltage according to the different reference voltages. The voltage output module can maintain the voltage adjustment capability when the voltage of the input end of the low-dropout linear voltage stabilizing circuit is high or low. Especially when the voltage of the input end of the low-dropout linear voltage stabilizing circuit is low, the reference voltage is automatically reduced to reduce the output voltage of the voltage output module, so that the voltage output module has better loop gain. The stable output of the voltage is realized under the wide range of the voltage of the input end of the low-dropout linear voltage stabilizing circuit, and the power supply ripple suppression capability is better.

[0046] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0048] Figure 1 is a structural schematic diagram of a low-dropout linear voltage stabilizing circuit according to an embodiment of the present application;

[0049] Figure 2 is a structural schematic diagram of another low-dropout linear voltage stabilizing circuit according to an embodiment of the present application;

[0050] Figure 3 is a voltage waveform diagram of a low-dropout linear voltage stabilizing circuit according to an embodiment of the present application;

[0051] Figure 4 is a structural schematic diagram of another low-dropout linear voltage stabilizing circuit according to an embodiment of the present application;

[0052] Figure 5 is a flowchart of a control method of a low-dropout linear voltage stabilizing circuit according to an embodiment of the present application;

[0053] Figure 6 is a flowchart of another control method of a low-dropout linear voltage stabilizing circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0054] In the following, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort should fall within the protection scope of the present application.

[0055] It should be noted that the terms "first", "second" and the like in the description and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units need not be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0056] The embodiment of the present application provides a low-dropout linear voltage stabilizing circuit. Figure 1 The embodiment of the present application provides a low-dropout linear voltage stabilizing circuit. Figure 1 The low-dropout linear voltage stabilizing circuit comprises a voltage sampling module 1, a voltage modulation module 2 and a voltage output module 3. The voltage sampling module 1 is connected to the input end of the low-dropout linear voltage stabilizing circuit, and is used for sampling the voltage V DD of the input end of the low-dropout linear voltage stabilizing circuit and outputting a first voltage V1. The first input end of the voltage modulation module 2 is connected to the output end of the voltage sampling module 1, and the second input end of the voltage modulation module 2 is connected to a first preset voltage V REF . The voltage modulation module 2 is used for reducing the reference voltage V REF when the first voltage V1 is less than the first preset voltage V REF-LDO ; and generating a constant reference voltage V REF when the first voltage V1 is greater than the first preset voltage V REF-LDO . The first input end of the voltage output module 3 is connected to the output end of the voltage modulation module 2, and the second input end of the voltage output module 3 is connected to the input end of the low-dropout linear voltage stabilizing circuit. The voltage output module 3 is used for voltage output according to the reference voltage V REF-LDO .

[0057] The low-dropout linear voltage stabilizing circuit is used for voltage output according to the voltage V DDthe output voltage of the voltage output module 3. The voltage sampling module 1 is configured to sample the voltage V DD at the input end of the low-dropout linear regulator and generate a first voltage V1, which is positively correlated with the voltage V DD at the input end of the low-dropout linear regulator. Therefore, the first voltage V1 can reflect the change in the voltage V DD at the input end of the low-dropout linear regulator. For example, when the voltage V DD at the input end of the low-dropout linear regulator increases, the first voltage V1 also increases; when the voltage V DD at the input end of the low-dropout linear regulator decreases, the first voltage V1 also decreases.

[0058] The second input end of the voltage modulation module 2 is connected with a constant first preset voltage V REF , and the reference voltage V REF is adjusted according to the magnitude relationship between the first preset voltage V REF-LDO and the first voltage V1. When the voltage modulation module 2 controls the reference voltage V REF-LDO to decrease, the output voltage of the voltage output module 3 decreases following the reference voltage V REF-LDO ; when the reference voltage V REF-LDO remains unchanged, the output voltage of the voltage output module 3 remains constant; when the reference voltage V REF-LDO increases, the output voltage of the voltage output module 3 increases following the reference voltage V REF-LDO .

[0059] Specifically, when the first voltage V1 is less than the first preset voltage V REF , it indicates that the voltage V DD at the input end of the low-dropout linear regulator is at a relatively low voltage level. For example, when the first voltage V1 is less than the first preset voltage V REF , the voltage V DD at the input end of the low-dropout linear regulator is less than the output voltage of the voltage output module 3. The voltage output module 3 cannot guarantee the loop regulation capability due to the too small voltage V DD at the input end of the low-dropout linear regulator, which further leads to the failure of the voltage output module 3 to regulate the output voltage according to the feedback of the output voltage.

[0060] To enable the voltage output module 3 to guarantee normal voltage regulation and output when the voltage V DD at the input end of the low-dropout linear regulator is low, the voltage modulation module 2 can lower the reference voltage V REF when the first voltage V1 is less than the first preset voltage V REF-LDO , so that the voltage output module 3 can regulate the output voltage according to the lower reference voltage VREF-LDO The output voltage is reduced. At this time, the voltage at the output end of the voltage output module 3 and the voltage V DD at the input end of the low-dropout linear regulator circuit can always have a certain difference, and the voltage output module 3 can adjust the output voltage through feedback of the output voltage, thereby maintaining the voltage regulation capability of the voltage output module 3 and having a good loop gain effect. Exemplarily, the voltage output module 3 detects the voltage output by the voltage output module 3. When the output voltage deviates due to factors such as fluctuation of the voltage V DD at the input end of the low-dropout linear regulator circuit and load change, the voltage output module 3 adjusts the output voltage to return to the set value, thereby realizing stable voltage output and outputting the voltage to the output end of the low-dropout linear regulator circuit.

[0061] When the first voltage V1 is greater than the first preset voltage V REF , it indicates that the voltage V DD at the input end of the low-dropout linear regulator circuit is at a relatively high voltage level. In this case, the voltage output module 3 is in a normal working state and has a good voltage regulation capability. Therefore, the voltage modulation module 2 can output a constant reference voltage V REF-LDO , so that the voltage output module 3 outputs a constant voltage value.

[0062] The technical scheme provided by the embodiment of the present application can sample the voltage at the input end of the low-dropout linear regulator circuit through the voltage sampling module. The voltage modulation module generates reference voltages of different sizes according to different voltages, so that the voltage output module can adjust the output voltage according to different reference voltages. The voltage regulation capability of the voltage output module can be maintained when the voltage at the input end of the low-dropout linear regulator circuit is relatively high or relatively low. Especially when the voltage at the input end of the low-dropout linear regulator circuit is relatively low, the reference voltage is automatically reduced to reduce the output voltage of the voltage output module, thereby making the voltage output module have a good loop gain. The stable voltage output is realized under a wide range of voltages at the input end of the low-dropout linear regulator circuit, and the power supply ripple suppression capability is good.

[0063] Figure 2 Another structure schematic diagram of a low-dropout linear regulator circuit is provided for the embodiment of the present application. Referring to Figure 2 , on the basis of the above embodiments, optionally, the voltage output module 3 comprises an error amplifier V EA , an eleventh transistor M 11 , a sixth resistor R6 and a seventh resistor R7. The positive input end of the error amplifier V EA is connected with the output end of the voltage modulation module 2, and the negative input end of the error amplifier V EAThe inverting input terminal is connected to the first terminal of the seventh resistor R7. The eleventh transistor M... 11 The first terminal is connected to the input terminal of the low-dropout linear regulator circuit, and the eleventh transistor M... 11 The second terminal is connected to the first terminal of the sixth resistor R6, and the eleventh transistor M 11 The second end serves as the output terminal of voltage output module 3; the second end of the sixth resistor R6 is connected to the first end of the seventh resistor R7, and the second end of the seventh resistor R7 is connected to the ground terminal.

[0064] Among them, error amplifier V EA It can be based on different reference voltages V at the positive input terminal REF-LDO The output voltage is adjusted. When the reference voltage V... REF-LDO When the error amplifier V decreases, EA The output voltage of transistor M rises, causing the eleventh transistor M to... 11 As the conductivity decreases, the current flowing through the sixth resistor R6 and the seventh resistor R7 decreases, and the output voltage of voltage output module 3 decreases. When the reference voltage V... REF-LDO During the rise, the error amplifier V EA The output voltage drops, and the eleventh transistor M... 11 The increased conductivity leads to an increase in the current flowing through the sixth resistor R6 and the seventh resistor R7, thereby increasing the output voltage of the voltage output module 3.

[0065] Error amplifier V EA The positive input terminal can be used to input the feedback voltage V. FB Feedback voltage V FB This can be the voltage across the seventh resistor R7. Error amplifier V EA According to the feedback voltage V FB and reference voltage V REF-LDO The difference, for the error amplifier V EA The output voltage is adjusted so that the voltage output module 3 can calibrate the output voltage, making the output voltage more accurate.

[0066] For example, the output terminal of voltage output module 3 can be connected to a load capacitor C. L and load resistance R L When the load at the output terminal of voltage output module 3 changes, it may cause the output voltage of voltage output module 3 to deviate. At this time, the feedback voltage V FB This voltage change can be fed back to the error amplifier V. EA This causes the eleven transistors M to output different voltages. 11 The conduction level is adjusted to regulate the output voltage of the voltage output module 3.

[0067] However, when the voltage V at the input terminal of the low dropout linear regulator circuit DD When the output voltage is lower than that of voltage output module 3, the error amplifier V EA Unable to pass feedback voltage V FB This is to maintain the ability to regulate the voltage. At this time, the voltage modulation module 2 controls the reference voltage V. REF-LDO This reduction lowers the output voltage of voltage output module 3, thereby ensuring the voltage V at the input of the low-dropout linear regulator circuit. DD A certain voltage difference between the output voltage and the error amplifier V maintains the voltage level of the error amplifier. EA It has good adjustment capability and good loop gain effect.

[0068] Figure 3 A voltage waveform diagram of a low-dropout linear regulator circuit is shown as an example. (Reference) Figure 3 Optionally, before time t1, the reference voltage V REF-LDO The output voltage V of voltage output module 3 gradually increases. OUT-LDO Follow the reference voltage V REF-LDO The reference voltage V increases accordingly. After time t1, the reference voltage V... REF-LDO In a stable state, the output voltage V of voltage output module 3 OUT-LDO It also remains stable. Therefore, the voltage output module 3 can follow the reference voltage V across different voltage ranges. REF-LDO The magnitude of the output voltage V OUT-LDO Stable output.

[0069] Figure 4 This is a schematic diagram of another low-dropout linear voltage regulator circuit provided in an embodiment of the present invention. (Refer to...) Figure 4 Based on the above embodiments, optionally, the voltage modulation module 2 includes: a current shunt unit 21 and a voltage generation unit 22. The first terminal of the current shunt unit 21 is connected to the input terminal of the low-dropout linear regulator circuit, the second terminal of the current shunt unit 21 is connected to the ground terminal, and the third terminal of the current shunt unit 21 is connected to a first preset voltage V. REF The fourth terminal of the current shunt unit 21 is connected to the output terminal of the voltage sampling module 1. The first terminal of the voltage generation unit 22 is connected to the input terminal of the low-dropout linear regulator circuit, the second terminal of the voltage generation unit 22 is connected to the ground terminal, and the third terminal of the voltage generation unit 22 is connected to the fifth terminal of the current shunt unit 21. The third terminal of the voltage generation unit 22 is also connected to the first input terminal of the voltage output module 3. The voltage generation unit 22 is used to generate the reference voltage V. REF-LDO The current shunt unit 21 is used to shunt currents according to a first preset voltage V. RBD The magnitude of the first voltage V1 is used to shunt the current in the voltage generation unit 22 to adjust the reference voltage V. REF-LDO.

[0070] The current shunt unit 21 can shunt the current in the voltage generation unit 22 to the reference voltage V generated by the voltage generation unit 22. REF-LDO Adjustments were made.

[0071] For example, when the first voltage V1 is less than the first preset voltage V REF At that time, the voltage V at the input terminal of the low dropout linear regulator circuit DD The voltage is less than the output voltage of voltage output module 3. Current shunt unit 21 shunts the current in voltage generation unit 22, reducing the current in voltage generation unit 22, and thus reducing the reference voltage V generated by voltage generation unit 22. REF-LDO It also decreases due to the decrease in current. Voltage output module 3 adjusts according to the reference voltage V. REF-LDO This causes the output voltage to decrease.

[0072] When the first voltage V1 is greater than the first preset voltage V REF At that time, the voltage V at the input terminal of the low dropout linear regulator circuit DD The voltage is greater than the output voltage of voltage output module 3. Current shunt unit 21 does not shunt the current in voltage generation unit 22, keeping the current in voltage generation unit 22 constant. Due to the constant current, voltage generation unit 22 maintains a constant reference voltage V. REF-LDO Maintain a stable voltage value. The output voltage of voltage output module 3 remains constant.

[0073] This embodiment of the invention, by setting a current shunt unit, can compare the magnitude of a first voltage with a first preset voltage. When the first voltage is less than the first preset voltage, the current in the voltage generation unit is shunted, causing the voltage generation unit to lower the reference voltage, thereby causing the voltage output module to lower the voltage output. This maintains the voltage regulation capability of the voltage output module when the input voltage of the low-dropout linear regulator circuit is low.

[0074] Continue to refer to Figure 4 Based on the above embodiments, optionally, the voltage generation unit 22 includes: a second current source I S2 And the first resistor R1. The second current source I. S2 The first terminal is connected to the input terminal of the low-dropout linear regulator circuit, and the second current source I... S2 The second end is connected to the fifth end of the current shunt unit 21, and the second current source I S2 The second terminal is also connected to the first terminal of the first resistor R1, and the second terminal of the first resistor R1 is connected to the ground terminal; the first resistor R1 is used to generate the reference voltage V. REF-LDO .

[0075] Among them, the second current source I S2This is used to provide a constant current to the first resistor R1, so that the first resistor R1 can generate a fixed reference voltage V. REF-LDO When the first voltage V1 is less than the first preset voltage V REF At that time, the current shunt unit 21 and the second current source I S2 A path is formed between them, allowing the second current source I to... S2 A portion of the current flows into the current shunt unit 21. At this time, the current in the input first resistor R1 decreases, and the reference voltage V... REF-LDO reduce.

[0076] When the first voltage V1 is greater than the first preset voltage V REF At that time, the current shunt unit 21 does not shunt the second current source I. S2 The current is shunted, so that the second current source I S2 All the current flows into the first resistor R1, because the second current source I S2 The output current is a constant, therefore, the reference voltage V REF-LDO It also remains a fixed value.

[0077] Continue to refer to Figure 4 Based on the above embodiments, optionally, the current shunt unit 21 includes: a first current source I S1 Branch 211, branch 212, and branch 213. First current source I. S1 The first terminal is connected to the input terminal of the low-dropout linear regulator circuit, and the first current source I... S1 The second end is connected to the first end of the first branch 211, and the first current source I S1 The second end is also connected to the first end of the second branch 212, and the second ends of both the first branch 211 and the second branch 212 are connected to the ground terminal. The third end of the first branch 211 is connected to the first preset voltage V. REF The third terminal of the second branch 212 is connected to the output terminal of the voltage sampling module 1. The first branch 211 and the second branch 212 are used to measure the first preset voltage V. REF The voltage is turned on or off according to the magnitude of the first voltage V1. The first terminal of the third branch 213 is connected to the third terminal of the voltage generation unit 22, the second terminal of the third branch 213 is connected to the fourth terminal of the second branch 212, and the third terminal of the third branch 213 is connected to the ground terminal; the third branch 213 is used to mirror the current of the second branch 212.

[0078] The first branch 211 is connected to a first preset voltage V. REF The second branch 212 is connected to a first voltage V1. When the first preset voltage V... REF When the voltage is greater than the first voltage V1, it indicates that the input voltage V of the low-dropout linear regulator circuit is... DDAt a lower voltage, the second branch 212 is turned on according to the lower first voltage V1, and the first current source I... S1 The current is input into the second branch 212. Since the first branch 211 is connected to a fixed first preset voltage V... REF At this time, the conductivity of the first branch 211 is much less than that of the second branch 212. The first branch 211 is essentially in a turned-off state, and the first current source I... S1 All current is input into the second branch 212.

[0079] When current flows into the second branch 212, the third branch 213 mirrors the current in the second branch 212 and generates the same current, which flows through the second current source I in the voltage generation unit 22. S2 Therefore, the second current source I is provided. S2 The current in the first input resistor R1 decreases, causing the reference voltage V to drop. REF-LDO The voltage output module 3 is reduced due to the reference voltage V. REF-LDO This reduces the voltage, which in turn lowers the output voltage.

[0080] When the first preset voltage V REF When the voltage is less than the first voltage V1, the second branch 212 is turned off due to the larger first voltage V1. At this time, the conduction degree of the first branch 211 is greater than that of the second branch 212, and the first current source I... S1 All current is input into the first branch 211, and the current in the second branch 212 is 0. Therefore, the current in the third branch 213 is also 0. At this time, the second current source I... S2 All the current is input into the first resistor R1, so that the reference voltage V REF-LDO Maintaining a constant value, voltage output module 3 outputs a constant voltage.

[0081] By setting up a first branch, a second branch, and a third branch, this embodiment of the invention can shunt the second current source when the input voltage of the low-dropout linear regulator circuit is low, thereby realizing the regulation of the reference voltage by the voltage generation unit and the regulation of the output voltage of the voltage output module, achieving a better regulation effect.

[0082] Continue to refer to Figure 4 Based on the above embodiments, optionally, the first branch 211 includes: a first transistor M1, a second transistor M2, a third transistor M3, and a second resistor R2. The first terminal of the first transistor M1 is connected to the first current source I. S1 The second terminal of the first transistor M1 is connected to the first terminal of the second resistor R2, and the control terminal of the first transistor M1 is connected to the first preset voltage V. REFThe first end of the second transistor M2 is connected with the second end of the second resistor R2, the second end of the second transistor M2 is connected with the first end of the third transistor M3, and the control end of the second transistor M2 is connected with the first end of the second resistor R2. The second end of the third transistor M3 is connected with the ground, and the control end of the third transistor M3 is connected with the second end of the second resistor R2.

[0083] The second branch 212 comprises a fourth transistor M4, a fifth transistor M5, a sixth transistor M6 and a third resistor R3. The first end of the fourth transistor M4 is connected with the second end of the first current source I S1 , the second end of the fourth transistor M4 is connected with the first end of the third resistor R3, and the control end of the fourth transistor M4 is connected with the output end of the voltage sampling module 1. The first end of the fifth transistor M5 is connected with the second end of the third resistor R3, the second end of the fifth transistor M5 is connected with the first end of the sixth transistor M6, and the control end of the fifth transistor M5 is connected with the first end of the third resistor R3. The second end of the sixth transistor M6 is connected with the ground, and the control end of the sixth transistor M6 is connected with the second end of the third resistor R3.

[0084] The third branch 213 comprises a seventh transistor M7 and an eighth transistor M8. The first end of the seventh transistor M7 is connected with the third end of the voltage generating unit 22, the second end of the seventh transistor M7 is connected with the first end of the eighth transistor M8, and the control end of the seventh transistor M7 is connected with the control end of the fifth transistor M5. The second end of the eighth transistor M8 is connected with the ground, and the control end of the eighth transistor M8 is connected with the control end of the sixth transistor M6.

[0085] The first transistor M1 is configured to receive a first preset voltage V REF . For example, the eighth resistor R8 can be connected in series between the gate of the first transistor M1 and the first preset voltage V REF , so as to limit the current flowing into the gate of the first transistor M1. The first capacitor C1 can also be connected in parallel between the gate of the first transistor M1 and the ground, so as to filter the first preset voltage V REF input into the gate of the first transistor M1.

[0086] The fourth transistor M4 is configured to receive a first voltage V1. When the first voltage V1 is greater than the first preset voltage V REF , the voltage V DD at the input end of the low dropout linear regulator is at a higher voltage level, and the voltage output module 3 is in a normal working state. At this time, the first transistor M1 is turned on, the fourth transistor M4 is turned off, and the first current source I S1The entire output current is input into the first branch 211 where the first transistor M1 is located. No current flows through the fifth transistor M5 and the sixth transistor M6; therefore, no current flows through the seventh transistor M7 and the eighth transistor M8 either. The second current source I... S2 All the current is input into the first resistor R1, and a fixed reference voltage V is generated. REF-LDO At this time, the output voltage of voltage output module 3 remains constant.

[0087] When the first voltage V1 is less than the first preset voltage V REF At that time, the voltage V at the input terminal of the low dropout linear regulator circuit DD At a lower voltage level, the fourth transistor M4 is turned on, while the conduction level of the first transistor M1 is much lower than that of the fourth transistor M4. The first current source I... S1 The output current is input into the second branch 212 where the fourth transistor M4 is located. The input current of the first transistor M1 is almost zero, which can be equivalent to the first branch 211 being in the off state. At this time, the second current source I... S2 Part of the output current is input into the seventh transistor M7 and the eighth transistor M8, so that the current flowing through the seventh transistor M7 and the eighth transistor M8 is consistent with the current flowing through the fifth transistor M5 and the sixth transistor M6. Second current source I S2 The current in the first resistor R1 decreases, causing the reference voltage V generated by the first resistor R1 to decrease. REF-LDO The voltage decreases, and at this point, the output voltage of voltage output module 3 decreases. Through this setting, the voltage V at the input terminal of the low-dropout linear regulator circuit can be reduced. DD When the voltage is low, the output voltage of the voltage output module 3 is automatically reduced, so that the voltage V at the input terminal of the low dropout linear regulator circuit is reduced. DD Maintaining a certain difference between the voltage output module 3 and the output voltage of the voltage output module 3 ensures the loop regulation capability of the voltage output module 3.

[0088] Continue to refer to Figure 4 Based on the above embodiments, optionally, the voltage sampling module 1 includes: a ninth transistor M9 and a tenth transistor M1. 10 The fourth resistor R4 and the fifth resistor R5. The first terminal of the fourth resistor R4 is connected to the input terminal of the low-dropout linear regulator circuit, the second terminal of the fourth resistor R4 is connected to the first terminal of the fifth resistor R5, and the second terminal of the fifth resistor R5 is connected to the ground terminal. The first terminal of the ninth transistor M9 is connected to the first input terminal of the voltage modulation module 2, the second terminal of the ninth transistor M9 is connected to the first terminal of the fifth resistor R5, and the control terminal of the ninth transistor M9 is connected to the tenth transistor M... 10 The first terminal is connected. The tenth transistor M 10 The second terminal is connected to the first terminal of the fifth resistor R5, and the tenth transistor M10 The first end is also connected to the tenth transistor M 10 The control terminal is connected.

[0089] The control terminal of the ninth transistor M9 can be connected to a second preset voltage V. PRE The ninth transistor M9 can be adjusted according to the second preset voltage V. PRE Maintaining the on state, when the voltage V at the input terminal of the low dropout linear regulator circuit remains on... DD When the voltage is low, the second preset voltage V PRE The voltage is greater than that of the fifth resistor R5, and the tenth transistor M 10 The body diode in the circuit is not conducting, and the first voltage V1 input to the fourth transistor M4 through the ninth transistor M9 is the voltage of the fifth resistor R5.

[0090] When the voltage V at the input terminal of the low dropout linear regulator circuit DD When it is higher, the second preset voltage V PRE The voltage is less than that of the fifth resistor R5, and the tenth transistor M 10 When the body diode is turned on, the first voltage V1 is equal to the second preset voltage V. PRE With the tenth transistor M 10 The voltage drop of the body diode in the transistor. Therefore, by setting the tenth transistor M... 10 This achieves a voltage V at the input terminal of the low dropout linear regulator circuit. DD When the voltage is high, the clamping of the first voltage V1 prevents the fourth transistor M4 from being damaged due to the excessively high first voltage V1.

[0091] This invention also provides a control method for a low-dropout linear regulator circuit. Applied to the low-dropout linear regulator circuit provided in any embodiment of this invention, this control method can be executed by the low-dropout linear regulator and can be implemented in software and / or hardware. Figure 5 A flowchart illustrating a control method for a low-dropout linear voltage regulator circuit provided in an embodiment of the present invention. (See reference...) Figure 5 The control methods for low-dropout linear voltage regulator circuits include:

[0092] S110. The voltage at the input terminal of the low-dropout linear regulator circuit is sampled by the voltage sampling module, and a first voltage is generated based on the voltage at the input terminal of the low-dropout linear regulator circuit.

[0093] The voltage sampling module is configured to sample the voltage at the input end of the low-dropout linear voltage regulator, and generate different first voltages according to the voltage at the input end of the low-dropout linear voltage regulator. Thus, the magnitude of the first voltage can reflect the magnitude of the voltage at the input end of the low-dropout linear voltage regulator. For example, when the voltage at the input end of the low-dropout linear voltage regulator is high, the first voltage is also high; when the voltage at the input end of the low-dropout linear voltage regulator is low, the first voltage is also low.

[0094] In S120, the voltage modulation module obtains the first voltage and a first preset voltage, and generates a reference voltage according to the first voltage and the first preset voltage.

[0095] The voltage modulation module can generate different reference voltages by comparing the magnitude relationship between the first voltage and the first preset voltage. The first preset voltage is a fixed voltage value. When the first voltage is greater than the first preset voltage, it indicates that the voltage at the input end of the low-dropout linear voltage regulator is at a high voltage level, for example, the voltage at the input end of the low-dropout linear voltage regulator is higher than the output voltage of the voltage output module. In this case, the voltage modulation module outputs a reference voltage with a fixed value.

[0096] When the first voltage is less than the first preset voltage, it indicates that the voltage at the input end of the low-dropout linear voltage regulator is at a low voltage level, for example, the voltage at the input end of the low-dropout linear voltage regulator is lower than the output voltage of the voltage output module. In this case, the voltage modulation module adjusts the reference voltage and reduces the reference voltage.

[0097] In S130, the voltage output module obtains the reference voltage and outputs a voltage according to the reference voltage.

[0098] When the reference voltage is different, the output voltage of the voltage output module is also different. When the first voltage is greater than the first preset voltage, the voltage modulation module outputs a reference voltage with a fixed value. Thus, in this case, the output voltage of the voltage output module remains constant.

[0099] When the first voltage is less than the first preset voltage, the voltage modulation module adjusts the reference voltage and reduces the reference voltage. The output voltage of the voltage output module is reduced according to the reduction of the reference voltage. The voltage at the input end of the low-dropout linear voltage regulator and the output voltage have a certain difference, thereby maintaining the voltage regulation capability of the voltage output module and achieving a good loop gain effect.

[0100] The technical scheme provided by the embodiment of the present application realizes detection and judgment of the voltage at the input end of the low-dropout linear voltage stabilizing circuit through comparison of the first voltage and the first preset voltage, and automatically reduces the reference voltage when the voltage at the input end of the low-dropout linear voltage stabilizing circuit is low, so that the voltage output module can reduce the output voltage, thereby ensuring the voltage regulation capability of the voltage output module. Therefore, the present application can ensure stable voltage output under a wide range of voltages at the input end of the low-dropout linear voltage stabilizing circuit, and has good power supply ripple suppression capability.

[0101] Figure 6 The flowchart of another control method of a low-dropout linear voltage stabilizing circuit provided by the embodiment of the present application is provided. Figure 6 The reference voltage is generated according to the first voltage and the first preset voltage, and includes:

[0102] S121, when the first voltage is less than the first preset voltage, the second branch and the third branch are turned on, the third branch shunts the current of the voltage generation unit, and the reference voltage is reduced.

[0103] When the voltage at the input end of the low-dropout linear voltage stabilizing circuit is low, the currents in the first current sources in the voltage modulation module all flow into the second branch, and the first branch does not flow current or only has a leakage current of almost 0. The third branch can mirror the current in the second branch and shunt the current in the voltage generation unit. The voltage generation unit reduces the reference voltage due to the reduction of the current, and the output voltage of the voltage output module is reduced according to the reduction of the reference voltage.

[0104] S122, when the first voltage is greater than the first preset voltage, the first branch is turned on, and the reference voltage remains a constant value.

[0105] When the voltage at the input end of the low-dropout linear voltage stabilizing circuit is high, the currents in the first current sources in the voltage modulation module input the first branch, and the second branch does not flow current, so the third branch also has no current flowing therethrough. The voltage generation unit outputs a constant value of the reference voltage. The output voltage of the voltage output module remains a constant value according to the constant value of the reference voltage.

[0106] The embodiment of the present application also provides a low-dropout linear voltage stabilizer. The low-dropout linear voltage stabilizer includes the low-dropout linear voltage stabilizing circuit provided by any embodiment of the present application, and has similar beneficial effects as the low-dropout linear voltage stabilizing circuit, which will not be repeated here.

[0107] It should be understood that the steps can be reordered, added or deleted using the various forms of flowcharts shown above. For example, the steps described in the present application can be executed in parallel, in sequence or in different orders, as long as the desired results of the technical scheme of the present application can be achieved, which is not limited herein.

[0108] The foregoing detailed description has set forth various embodiments of the application via specific examples. However, it is noted that various modifications, combinations, sub-combinations, and equivalents can be employed, and will be apparent to one skilled in the art. Accordingly, the specific disclosure of the application is intended to be illustrative, but not limiting, of the scope of the application, which is set forth in the following claims.

Claims

1. A low-dropout linear voltage regulator circuit, characterized in that, include: A voltage sampling module is connected to the input terminal of the low dropout linear regulator circuit and is used to sample the voltage at the input terminal of the low dropout linear regulator circuit and output a first voltage. A voltage modulation module is provided, wherein a first input terminal of the voltage modulation module is connected to the output terminal of the voltage sampling module, and a second input terminal of the voltage modulation module is connected to a first preset voltage. The voltage modulation module is used to reduce the reference voltage when the first voltage is less than the first preset voltage, and to generate a constant reference voltage when the first voltage is greater than the first preset voltage. A voltage output module, wherein the first input terminal of the voltage output module is connected to the output terminal of the voltage modulation module, and the second input terminal of the voltage output module is connected to the input terminal of the low dropout linear regulator circuit, and the voltage output module is used to output voltage according to the reference voltage.

2. The low-dropout linear voltage regulator circuit according to claim 1, characterized in that, The voltage modulation module includes: a current shunt unit and a voltage generation unit; The first terminal of the current shunt unit is connected to the input terminal of the low dropout linear regulator circuit, the second terminal of the current shunt unit is connected to the ground terminal, the third terminal of the current shunt unit is connected to the first preset voltage, and the fourth terminal of the current shunt unit is connected to the output terminal of the voltage sampling module. The first terminal of the voltage generation unit is connected to the input terminal of the low dropout linear regulator circuit, the second terminal of the voltage generation unit is connected to the ground terminal, and the third terminal of the voltage generation unit is connected to the fifth terminal of the current shunt unit; the third terminal of the voltage generation unit is also connected to the first input terminal of the voltage output module, and the voltage generation unit is used to generate the reference voltage; The current shunt unit is used to shunt the current of the voltage generation unit according to the first preset voltage and the magnitude of the first voltage, so as to adjust the reference voltage.

3. The low-dropout linear voltage regulator circuit according to claim 2, characterized in that, The voltage generation unit includes: a second current source and a first resistor; The first terminal of the second current source is connected to the input terminal of the low dropout linear regulator circuit, the second terminal of the second current source is connected to the fifth terminal of the current shunt unit, the second terminal of the second current source is also connected to the first terminal of the first resistor, and the second terminal of the first resistor is connected to the ground terminal; the first resistor is used to generate the reference voltage.

4. The low-dropout linear voltage regulator circuit according to claim 2, characterized in that, The current shunt unit includes: a first current source, a first branch, a second branch, and a third branch; The first terminal of the first current source is connected to the input terminal of the low dropout linear regulator circuit, the second terminal of the first current source is connected to the first terminal of the first branch, the second terminal of the first current source is also connected to the first terminal of the second branch, and the second terminals of the first branch and the second branch are both connected to the ground terminal. The third terminal of the first branch is connected to the first preset voltage, and the third terminal of the second branch is connected to the output terminal of the voltage sampling module; the first branch and the second branch are used to turn on or off according to the magnitude of the first preset voltage and the first voltage. The first end of the third branch is connected to the third end of the voltage generation unit, the second end of the third branch is connected to the fourth end of the second branch, and the third end of the third branch is connected to the ground terminal; the third branch is used to mirror the current of the second branch.

5. The low-dropout linear voltage regulator circuit according to claim 4, characterized in that, The first branch includes: a first transistor, a second transistor, a third transistor, and a second resistor; The first terminal of the first transistor is connected to the second terminal of the first current source, the second terminal of the first transistor is connected to the first terminal of the second resistor, and the control terminal of the first transistor is connected to the first preset voltage. The first terminal of the second transistor is connected to the second terminal of the second resistor, the second terminal of the second transistor is connected to the first terminal of the third transistor, and the control terminal of the second transistor is connected to the first terminal of the second resistor. The second terminal of the third transistor is connected to the ground terminal, and the control terminal of the third transistor is connected to the second terminal of the second resistor; The second branch includes: a fourth transistor, a fifth transistor, a sixth transistor, and a third resistor; The first terminal of the fourth transistor is connected to the second terminal of the first current source, the second terminal of the fourth transistor is connected to the first terminal of the third resistor, and the control terminal of the fourth transistor is connected to the output terminal of the voltage sampling module. The first terminal of the fifth transistor is connected to the second terminal of the third resistor, the second terminal of the fifth transistor is connected to the first terminal of the sixth transistor, and the control terminal of the fifth transistor is connected to the first terminal of the third resistor. The second terminal of the sixth transistor is connected to the ground terminal, and the control terminal of the sixth transistor is connected to the second terminal of the third resistor; The third branch includes: a seventh transistor and an eighth transistor; The first terminal of the seventh transistor is connected to the third terminal of the voltage generation unit, the second terminal of the seventh transistor is connected to the first terminal of the eighth transistor, and the control terminal of the seventh transistor is connected to the control terminal of the fifth transistor. The second terminal of the eighth transistor is connected to the ground terminal, and the control terminal of the eighth transistor is connected to the control terminal of the sixth transistor.

6. The low-dropout linear voltage regulator circuit according to claim 1, characterized in that, The voltage sampling module includes: a ninth transistor, a tenth transistor, a fourth resistor, and a fifth resistor; The first end of the fourth resistor is connected to the input terminal of the low dropout linear regulator circuit, the second end of the fourth resistor is connected to the first end of the fifth resistor, and the second end of the fifth resistor is connected to the ground terminal. The first terminal of the ninth transistor is connected to the first input terminal of the voltage modulation module, the second terminal of the ninth transistor is connected to the first terminal of the fifth resistor, and the control terminal of the ninth transistor is connected to the first terminal of the tenth transistor. The second terminal of the tenth transistor is connected to the first terminal of the fifth resistor, and the first terminal of the tenth transistor is also connected to the control terminal of the tenth transistor.

7. The low-dropout linear voltage regulator circuit according to claim 1, characterized in that, The voltage output module includes: an error amplifier, an eleventh transistor, a sixth resistor, and a seventh resistor; The positive input terminal of the error amplifier is connected to the output terminal of the voltage modulation module, and the inverting input terminal of the error amplifier is connected to the first terminal of the seventh resistor. The first terminal of the eleventh transistor is connected to the input terminal of the low dropout linear regulator circuit, the second terminal of the eleventh transistor is connected to the first terminal of the sixth resistor, and the second terminal of the eleventh transistor serves as the output terminal of the voltage output module; the second terminal of the sixth resistor is connected to the first terminal of the seventh resistor, and the second terminal of the seventh resistor is connected to the ground terminal.

8. A control method for a low-dropout linear voltage regulator circuit, characterized in that, Applied to the low dropout linear regulator circuit as described in any one of claims 1-7; the control method of the low dropout linear regulator circuit includes: The voltage at the input terminal of the low dropout linear regulator circuit is sampled by the voltage sampling module, and a first voltage is generated based on the voltage at the input terminal of the low dropout linear regulator circuit. The voltage modulation module acquires the first voltage and the first preset voltage, and generates a reference voltage based on the first voltage and the first preset voltage; The voltage output module acquires the reference voltage and outputs a voltage based on the reference voltage.

9. The control method for the low-dropout linear voltage regulator circuit according to claim 8, characterized in that, The step of generating a reference voltage based on the first voltage and the first preset voltage includes: When the first voltage is less than the first preset voltage, the second branch and the third branch are turned on, the third branch shunts the current of the voltage generation unit, and the reference voltage decreases; When the first voltage is greater than the first preset voltage, the first branch is turned on, and the reference voltage remains constant.

10. A low-dropout linear regulator, characterized in that, include: The low dropout linear regulator circuit according to any one of claims 1-7.

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