Voltage stabilizing and regulating circuit and electronic equipment

Abstract

The invention relates to a voltage stabilization regulation circuit and electronic equipment, the voltage stabilization regulation circuit comprises a voltage stabilization regulation unit and a current limiting value regulation unit, the voltage stabilization regulation unit is suitable for providing a constant output voltage; the current limiting value adjusting unit is suitable for limiting the output current of the voltage stabilization adjusting unit when the output of the voltage stabilization adjusting unit is short-circuited; when the output voltage of the voltage stabilizing and regulating unit is reduced to the first voltage, the output current is limited to a first current limiting value; when the output voltage of the voltage stabilizing and adjusting unit drops to the second voltage, the output current is limited to a second current limiting value, the first voltage is larger than the second voltage, and the first current limiting value is larger than the second current limiting value. According to the scheme, the current limiting value of the output current of the voltage stabilizing and regulating unit can be regulated when the voltage stabilizing and regulating unit has an output short circuit, so that the temperature of the power tube is prevented from rapidly rising.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and in particular to a voltage regulation circuit and electronic device. Background Technology

[0002] A voltage regulator (LDO) is a linear regulator used to provide a stable output voltage by adjusting the current of its internal power transistor to maintain a constant output voltage. Voltage regulators are widely used in electronic devices.

[0003] Voltage regulator circuits are susceptible to damage under high load current or output short circuit conditions. Adding a current-limiting protection module to the voltage regulator circuit can improve its reliability. When the output of the voltage regulator circuit is short-circuited, the output current will be limited to a constant value, thereby preventing damage to the components due to excessive current.

[0004] In some specialized applications, such as the automotive industry, the input voltage of a voltage regulator circuit can reach as high as 40V. When the output of the voltage regulator circuit is short-circuited, the power transistor within it will bear a large amount of power, causing its temperature to rise rapidly and potentially leading to damage. Summary of the Invention

[0005] The purpose of this invention is at least to provide a voltage regulation circuit that can dynamically adjust the current in the power transistor when the output of the voltage regulation circuit is short-circuited, thereby limiting the output current and limiting the power on the power transistor.

[0006] In a first aspect, the present invention provides a voltage regulation circuit, comprising: a voltage regulation unit and a current limiting adjustment unit, wherein: the voltage regulation unit is adapted to provide a constant output voltage; the current limiting adjustment unit is adapted to limit the output current of the voltage regulation unit when the output of the voltage regulation unit is short-circuited; when the output voltage of the voltage regulation unit drops to a first voltage, the output current is limited to a first current limiting value; when the output voltage of the voltage regulation unit drops to a second voltage, the output current is limited to a second current limiting value, wherein the first voltage is greater than the second voltage, and the first current limiting value is greater than the second current limiting value.

[0007] When a short circuit occurs at the output of the voltage regulator unit, the current limiting adjustment unit limits the output current of the voltage regulator unit. When the output voltage of the voltage regulator unit drops to a first voltage, the output current is limited to a first current limit value; when the output voltage drops to a lower second voltage, the output current is limited to a second current limit value, where the first current limit value is greater than the second current limit value. Therefore, during a short circuit at the output of the voltage regulator unit, the current limit value of the output current is adjusted, gradually decreasing the current limit value, thereby preventing a rapid rise in the temperature of the power transistor.

[0008] Optionally, the voltage regulation unit includes: a first resistor, a second resistor, a first current source, an overcurrent protection comparator, an error amplifier, a current sensor, a power transistor, a first sampling resistor, and a second sampling resistor, wherein: the first resistor has a first voltage input at its first terminal and its second terminal coupled to the first input terminal of the overcurrent protection comparator and the first terminal of the first current source; the second resistor has the first voltage input at its first terminal and its second terminal coupled to the second input terminal of the overcurrent protection comparator and the first terminal of the current sensor; the first current source has its second terminal grounded; the overcurrent protection comparator has its output terminal coupled to the gate of the power transistor; the error amplifier has its first input terminal coupled between the second terminal of the first sampling resistor and the first terminal of the second sampling resistor, its second input terminal inputting a first reference voltage, and its output terminal coupled to the gate of the power transistor; the power transistor has the first voltage input at its source and coupled to the second terminal of the current sensor, and its drain coupled to the first terminal of the first sampling resistor; the first sampling resistor has its second terminal coupled to the first terminal of the second sampling resistor; the second sampling resistor has its second terminal grounded.

[0009] Optionally, the current limiting adjustment unit includes: a current limiting adjustment unit adapted to reduce the current flowing through the first resistor in a stepwise manner to the output current of the first current source during the continuous decrease of the output voltage of the voltage regulation unit.

[0010] Optionally, the current limiting adjustment unit includes N adjustment sub-modules; wherein, the i-th adjustment sub-module includes: an i-th second current source, an i-th first switching unit, and an i-th third sampling resistor, wherein: the i-th second current source has its first terminal coupled to the first terminal of the first current source, and its second terminal coupled to the first terminal of the i-th first switching unit; the i-th first switching unit has its second terminal coupled to the second terminal of the first current source, and its control terminal coupled to the first terminal of the i-th third sampling resistor; the i-th third sampling resistor is set in a sampling resistor string, its first terminal coupled to the first input terminal of the error amplifier, and its second terminal coupled to the first terminal of the (i+1)-th third sampling resistor; the sampling resistor string is formed by connecting the first sampling resistor, the second sampling resistor, and N third sampling resistors in series, the first terminal of the sampling resistor string is coupled to the output terminal of the voltage regulation circuit, and the second terminal of the sampling resistor string is grounded; i is a positive integer and i≤N.

[0011] Optionally, the current limiting adjustment unit is adapted to continuously reduce the current flowing through the first resistor to the output current of the first current source during the continuous decrease of the output voltage of the voltage regulation unit.

[0012] Optionally, the current limiting adjustment unit includes: an operational amplifier, a third switching unit, and a variable impedance device, wherein: the first terminal of the third switching unit is coupled to the first terminal of the first current source, the second terminal of the third switching unit is coupled to the first terminal of the variable impedance device, and the control terminal of the third switching unit is coupled to the output terminal of the operational amplifier; the operational amplifier has a second reference voltage input at its first input terminal, and its second input terminal is coupled to the second terminal of the third switching unit and the first terminal of the variable impedance device; the variable impedance device has a second terminal coupled to the second terminal of the first current source.

[0013] Optionally, the impedance value of the variable impedance device is negatively correlated with the output voltage of the voltage regulation unit.

[0014] Optionally, the variable impedance device includes a MOS transistor, wherein: the drain of the MOS transistor is coupled to the second terminal of the third switching unit, the source is coupled to the second terminal of the first current source, and the gate is coupled to the first terminal of the second sampling resistor.

[0015] Secondly, the present invention also provides an electronic device including the voltage regulation circuit provided in any of the above embodiments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a voltage regulation circuit.

[0017] Figure 2 yes Figure 1 The voltage regulation circuit in the diagram shows the volt-ampere characteristic curve at the output terminal.

[0018] Figure 3 This is a schematic diagram of a voltage regulation circuit according to an embodiment of the present invention;

[0019] Figure 4 yes Figure 3 The corresponding voltage regulation circuit output current-voltage characteristic curve;

[0020] Figure 5 This is a schematic diagram of another voltage regulation circuit in an embodiment of the present invention;

[0021] Figure 6 yes Figure 5 The corresponding voltage regulation circuit output voltage-current characteristic curve. Detailed Implementation

[0022] Reference Figure 1 A schematic diagram of an existing voltage regulation circuit is given. The voltage regulation circuit includes: a first resistor R0, a second resistor R1, a current source, an overcurrent protection comparator OCP, an error amplifier EA, a current sensor, a power transistor MP, a first sampling resistor Rfb1, and a second sampling resistor Rfb2.

[0023] The first voltage VIN is input to the first terminal of the first resistor R0, and the second terminal of the first resistor R0 is coupled to the first input terminal of the overcurrent protection comparator OCP and the first terminal of the current source.

[0024] The first terminal of the second resistor R1 is input to the first voltage VIN, and the second terminal of the second resistor R1 is coupled to the second input terminal of the overcurrent protection comparator OCP and the first terminal of the current sensor.

[0025] The second terminal of the current source is grounded, and the output current is IB.

[0026] The output of the overcurrent protection comparator OCP is coupled to the gate of the power transistor MP.

[0027] The first input terminal of the error amplifier EA is coupled between the second terminal of the first sampling resistor Rfb1 and the first terminal of the second sampling resistor Rfb2. The second input terminal of the error amplifier EA is input with the first reference voltage Vref1. The output terminal of the error amplifier EA is coupled to the gate of the power transistor MP.

[0028] The power transistor MP can be a PMOS transistor; the source of the power transistor MP is input to the first voltage VIN, and the drain of the power transistor MP is coupled to the first terminal of the first sampling resistor Rfb1.

[0029] The second terminal of the first sampling resistor Rfb1 is coupled to the first terminal of the second sampling resistor Rfb2, and the second terminal of the second sampling resistor Rfb2 is grounded.

[0030] When a short circuit occurs at the output terminal of the voltage regulator circuit, the output current of the voltage regulator circuit will be limited to a constant value. Assuming that the resistance of the first resistor R0 is equal to the resistance of the second resistor R1, the output current will be limited to ILIMIT = IB × K, where K is the scaling factor of the current sensor.

[0031] like Figure 2 As shown, it gives Figure 1 The voltage regulator circuit's output voltage-current characteristic curve is shown in the diagram. When the voltage regulator circuit is working normally, the output voltage is Vnominal; when a short circuit occurs at the output of the voltage regulator circuit, the output voltage drops rapidly to 0V, and the output current is limited to ILIMIT.

[0032] Currently, when a short circuit occurs at the output of the voltage regulator circuit, the output current of the voltage regulator circuit is limited to a fixed value ILIMIT.

[0033] However, in some high-voltage applications, such as in the automotive industry, the initial input voltage VIN of the voltage regulator circuit may be as high as 40V. When a short circuit occurs at the output of the voltage regulator circuit, the power transistor MP in the voltage regulator circuit will bear a power of P=ILIMIT×VIN, causing the temperature of the power transistor MP to rise rapidly and potentially damaging the device.

[0034] In this embodiment of the invention, when a short circuit occurs at the output of the voltage regulator unit, the current limiting adjustment unit limits the output current of the voltage regulator unit. When the output voltage of the voltage regulator unit drops to a first voltage, the output current is limited to a first current limiting value; when the output voltage of the voltage regulator unit drops to a lower second voltage, the output current is limited to a second current limiting value, where the first current limiting value is greater than the second current limiting value. Therefore, during the short circuit process at the output of the voltage regulator unit, the current limiting value of the output current is adjusted, gradually reducing the current limiting value, thereby preventing a rapid rise in the temperature of the power transistor MP.

[0035] To make the above-mentioned objectives, features and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0036] This invention provides a voltage regulation circuit, including: a voltage regulation unit and a current limiting adjustment unit, wherein:

[0037] A voltage regulator unit, suitable for providing a constant output voltage;

[0038] The current limiting adjustment unit is suitable for limiting the output current of the voltage regulator unit when the output of the voltage regulator unit is short-circuited; when the output voltage of the voltage regulator unit drops to a first voltage, the output current of the voltage regulator unit is limited to a first current limiting value; when the output voltage of the voltage regulator unit drops to a second voltage, the output current is limited to a second current limiting value; the first voltage is greater than the second voltage, and the first current limiting value is greater than the second current limiting value.

[0039] In this embodiment of the invention, the aforementioned current-voltage regulation unit can employ a voltage-voltage regulation circuit provided in the prior art, the circuit structure of which is as follows: Figure 1 As shown in .

[0040] It should be noted that in the current regulation unit of this invention embodiment, the current source coupled to the first resistor R0 is the first current source.

[0041] In this embodiment of the invention, as the output voltage of the voltage regulator unit decreases, the current limiting value of the output current of the voltage regulator unit can decrease in a stepwise manner or decrease continuously.

[0042] The aforementioned stepped decrease refers to the existence of a current limit for the output current when the output voltage of the voltage regulator unit is within a certain range. The current limit varies for different ranges. The magnitude of the current limit is related to the minimum voltage value of the range. The larger the minimum voltage value of the range, the larger the corresponding current limit.

[0043] For example, when the output voltage of the voltage regulator unit is in the first range (e.g., less than VOUT and greater than V1), the current limiting value of the output current of the voltage regulator unit is ILIMIT1; when the output voltage of the voltage regulator unit is in the second range (e.g., less than V1 and greater than V2), the current limiting value of the output current of the voltage regulator unit is ILIMIT2. V1 is the first voltage, V2 is the second voltage, ILIMIT1 is the first current limiting value, and ILIMIT2 is the second current limiting value.

[0044] In combination with the above regarding Figure 1 As described above, the current limit value of the output current is related to the scaling factor K of the current sensor and the current flowing through the first resistor R0. Therefore, by adjusting the current flowing through the first resistor R0, the current limit value of the output current can be adjusted.

[0045] In practical implementation, the current limiting adjustment unit can reduce the current flowing through the first resistor R0 in a stepwise manner when the output of the voltage regulation unit is short-circuited, thereby reducing the current limiting value of the output current in a stepwise manner.

[0046] In practice, the current limiting adjustment unit can include N adjustment sub-modules, and the structures of different adjustment sub-modules can be the same.

[0047] In some embodiments, the i-th adjustment submodule includes: an i-th second current source, an i-th first switching unit, and an i-th third sampling resistor, wherein:

[0048] The first terminal of the i-th second current source is coupled to the first terminal of the first current source, and the second terminal of the i-th second current source is coupled to the first terminal of the i-th first switching unit.

[0049] The second terminal of the i-th first switching unit is coupled to the second terminal of the first current source, and the control terminal of the i-th first switching unit is coupled to the first terminal of the i-th third sampling resistor.

[0050] The i-th third sampling resistor is set in the sampling resistor string; the second end of the i-th third sampling resistor is coupled to the first end of the (i+1)-th third sampling resistor; the sampling resistor string is formed by the first sampling resistor, the second sampling resistor and N third sampling resistors connected in series, the first end of the sampling resistor string is coupled to the output end of the voltage regulation circuit, and the second end of the sampling resistor string is grounded; i is a positive integer and i≤N.

[0051] The voltage regulation circuit provided in the embodiments of the present invention will be described in detail below.

[0052] Reference Figure 3 This invention provides a voltage regulation circuit according to an embodiment of the invention. Figure 1 Based on the provided circuit structure, a current limiting adjustment unit has been added.

[0053] Figure 3 In the middle, the current limiting value adjustment unit includes two adjustment sub-modules, wherein: the first adjustment sub-module includes a second current source, a switching unit M1 and a sampling resistor Rfb3, and the second adjustment sub-module includes a second current source, a switching unit M2 and a sampling resistor Rfb4.

[0054] Specifically, in the first adjustment submodule, the first terminal of the second current source is coupled to the first terminal of the first current source, and the second terminal of the second current source is coupled to the first terminal of the switching unit M1; the output current of the second current source is IB1.

[0055] The control terminal of the switching unit M1 is coupled to the second terminal of the sampling resistor Rfb3, and the second terminal of the switching unit M1 is coupled to the second terminal of the first current source.

[0056] The first terminal of the sampling resistor Rfb3 is coupled to the first input terminal of the error amplifier EA, and the second terminal of the sampling resistor Rfb3 is coupled to the first terminal of the sampling resistor Rfb4.

[0057] In the second adjustment submodule, the first terminal of the second current source is coupled to the first terminal of the first current source, the second terminal of the second current source is coupled to the first terminal of the switching unit M2, and the output current of the second current source is IB2.

[0058] The control terminal of the switching unit M2 is coupled to the second terminal of the sampling resistor Rfb4, and the second terminal of the switching unit M2 is coupled to the second terminal of the first current source; the second terminal of the sampling resistor Rfb4 is grounded.

[0059] In practical implementation, if the current limiting adjustment unit only includes one adjustment submodule, then... Figure 3 By removing the second adjustment submodule (i.e., the second current source, the switching unit M2, and the sampling resistor Rfb4) from the existing circuit, the corresponding voltage regulation circuit can be obtained.

[0060] If the current limiting adjustment unit includes three or more adjustment sub-modules, then... Figure 3 Based on this, a corresponding second current source, a first switching unit, and a third sampling resistor are set up.

[0061] In a specific implementation, the first switching unit mentioned above can be an NMOS transistor. The first terminal of the first switching unit is the drain of the NMOS transistor, the second terminal of the first switching unit is the source of the NMOS transistor, and the control terminal of the first switching unit is the gate of the NMOS transistor.

[0062] The following is based on Figure 3 Taking the voltage regulation circuit provided in the above embodiments of the present invention as an example, the working principle of the voltage regulation circuit will be explained.

[0063] Set the resistance value of the first resistor R0 to be equal to the resistance value of the second resistor R1.

[0064] When the output voltage VOUT of the voltage regulator unit is normal (i.e., the output voltage is Vnominal), the gate voltages of both switching units M1 and M2 are higher than their corresponding threshold voltages, so both switching units M1 and M2 are turned on. When both switching units M1 and M2 are turned on, the current flowing through the first resistor R0 includes the output current IB0 of the first current source, the output current IB1 of the second current source, and the output current IB2 of the second current source. The current limiting value of the output current IOUT of the voltage regulator unit is ILIMIT = (IB0 + IB1 + IB2) × K.

[0065] When the output voltage VOUT of the voltage regulator unit drops to a certain value, the gate voltage of the switching unit M2 is less than its threshold voltage, while the gate voltage of the switching unit M1 is greater than its threshold voltage. Switching unit M2 remains in the on state, and switching unit M2 is in the off state. At this time, the current flowing through the first resistor R0 includes the output current IB0 of the first current source and the output current IB1 of the second current source. The current limiting value of the output current IOUT of the voltage regulator unit is ILIMIT = (IB0 + IB1) ​​× K.

[0066] As the output voltage VOUT of the voltage regulator unit continues to decrease, the gate voltage of the switching unit M1 becomes less than its threshold voltage. Therefore, the switching unit M1 switches from the on state to the off state, while the switching unit M2 remains off. At this time, the current flowing through the first resistor R0 includes the output current IB0 of the first current source, and the current limiting value for the output current IOUT of the voltage regulator unit is ILIMIT = IB0 × K.

[0067] Reference Figure 4 It gives the same as Figure 3 The voltage regulation circuit in the diagram shows the volt-ampere characteristic curve of the output terminal. Figure 4 In the above, when the output voltage VOUT of the voltage regulator unit does not change, the corresponding current limiting value ILIMIT is (IB0+IB1+IB2)×K; when the output voltage VOUT of the voltage regulator unit drops to a certain value, the corresponding current limiting value ILIMIT is (IB0+IB1)×K; when the output voltage VOUT of the voltage regulator unit continues to drop, the corresponding current limiting value ILIMIT is IB0×K.

[0068] In practical implementation, the current limiting adjustment unit can continuously reduce the current flowing through the first resistor R0 when the output of the voltage regulation unit is short-circuited, thereby continuously reducing the current limiting value of the output current.

[0069] The aforementioned continuous decrease can refer to the following: as the output voltage of the voltage regulator unit continuously decreases, the current limit value of the output current of the voltage regulator unit also continuously decreases. In other words, the current limit value of the output current of the voltage regulator unit is negatively correlated with the output voltage of the voltage regulator unit.

[0070] In this embodiment of the invention, the current limiting adjustment unit may include: an operational amplifier, a third switching unit, and a variable impedance device, wherein:

[0071] The first terminal of the third switching unit is coupled to the first terminal of the first current source, the second terminal of the third switching unit is coupled to the first terminal of the impedance variable device, and the control terminal of the third switching unit is coupled to the output terminal of the operational amplifier.

[0072] The first input terminal of the operational amplifier receives the second reference voltage, and the second input terminal of the operational amplifier is coupled to the second terminal of the third switching unit and the first terminal of the impedance variable device.

[0073] The second terminal of the variable impedance device is coupled to the second terminal of the first current source.

[0074] In practical implementation, the changing trend of the impedance value of the variable impedance device can be negatively correlated with the changing trend of the output voltage of the voltage regulation unit.

[0075] In other words, as the output voltage of the voltage regulator unit decreases, the impedance value of the variable impedance device increases accordingly; as the output voltage of the voltage regulator unit increases, the impedance value of the variable impedance device decreases accordingly.

[0076] In some embodiments, the variable impedance device can be a variable resistor, and the trend of the resistance value of the variable resistor is negatively correlated with the trend of the output voltage of the voltage regulation unit.

[0077] In other embodiments, the variable impedance device can be a MOSFET. The drain of the MOSFET is coupled to the second terminal of the third switching unit, the source of the MOSFET is coupled to the second terminal of the first current source, and the gate of the MOSFET is coupled to the first terminal of the second sampling resistor Rfb2. The changing trend of the on-resistance of the MOSFET is negatively correlated with the changing trend of the output voltage of the voltage regulation unit.

[0078] Reference Figure 5 The present invention provides a schematic diagram of another voltage regulation circuit in an embodiment of the present invention. Figure 5 In the middle, the third switching unit is MOSFET M3, and the variable impedance device is MOSFET M4.

[0079] The drain of MOSFET M3 is coupled to the first terminal of the first current source, the gate of MOSFET M3 is coupled to the output terminal of the operational amplifier, and the source of MOSFET M3 is coupled to the second input terminal of the operational amplifier and the drain of MOSFET M4.

[0080] The gate of MOSFET M4 is coupled to the first terminal of sampling resistor Rfb2, and the source of MOSFET M4 is coupled to the second terminal of the first current source.

[0081] The first input terminal of the operational amplifier receives the second reference voltage Vref2.

[0082] The following is about Figure 5 The working principle of the voltage regulation circuit provided in the document will be explained.

[0083] Assume that the resistance of the first resistor R0 is equal to the resistance of the second resistor R1.

[0084] The on-resistance of MOSFET M4 is:

[0085] ;

[0086] Where u is the carrier mobility of MOSFET M4, Cox is the gate oxide capacitance per unit area, W / L is the width-to-length ratio of MOSFET M4, and V th This is the threshold voltage of MOSFET M4.

[0087] The current flowing through MOSFET M4 is:

[0088] ;

[0089] The above formula can be simplified to H0 can be considered a constant, where:

[0090] ;

[0091] ;

[0092] but .

[0093] It can be seen that when the output voltage VOUT of the voltage regulator unit changes, ILIMIT also changes accordingly, and the trend of ILIMIT is positively correlated with the trend of VOUT.

[0094] As the output voltage VOUT gradually decreases, when the output voltage VOUT drops to a certain value, the MOSFET M4 is turned off. At this time, ILIMIT is IB0×K.

[0095] Reference Figure 6 It gives the same as Figure 5 The output characteristic curve of the voltage regulation circuit in the diagram is shown. Figure 6 In the current limiting mechanism, when the output voltage VOUT of the voltage regulator unit remains unchanged, the corresponding current limiting value is (IB0 + IB1_max) × K. As the output voltage VOUT decreases, ILIMIT also gradually decreases. When the output voltage of the voltage regulator unit drops to a certain value, the corresponding current limiting value is IB0 × K. IB1_max is the maximum value of IB1, which is the value of IB1 when the output voltage VOUT does not decrease.

[0096] It should be noted that, as Figure 1 In the provided voltage regulation circuit, IB can be equal to IB0+IB1+IB2 in the embodiment of the present invention; or, IB can be equal to IB0+IB1_max.

[0097] In other words, compared with the voltage regulation circuit provided in the prior art, the voltage regulation circuit provided in this embodiment of the invention can reduce the current limiting value of the output current of the voltage regulation unit when an output short circuit occurs.

[0098] In summary, in this embodiment of the invention, when a short circuit occurs at the output of the voltage regulator unit, the current limiting adjustment unit limits the output current of the voltage regulator unit. When the output voltage of the voltage regulator unit drops to a first voltage, the output current is limited to a first current limiting value; when the output voltage of the voltage regulator unit drops to a lower second voltage, the output current is limited to a second current limiting value, where the first current limiting value is greater than the second current limiting value. Therefore, during the short circuit process at the output of the voltage regulator unit, the current limiting value of the output current is adjusted, gradually reducing the current limiting value, thereby preventing a rapid rise in the temperature of the power transistor.

[0099] The present invention also provides an electronic device, including the voltage regulation circuit provided in any of the above embodiments.

[0100] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A voltage regulation circuit, characterized in that, include: The voltage regulation unit and the current limiting adjustment unit, wherein: The voltage regulation unit is adapted to provide a constant output voltage; The current limiting adjustment unit is adapted to limit the output current of the voltage regulator unit when the output of the voltage regulator unit is short-circuited; when the output voltage of the voltage regulator unit drops to a first voltage, the output current is limited to a first current limiting value; when the output voltage of the voltage regulator unit drops to a second voltage, the output current is limited to a second current limiting value, wherein the first voltage is greater than the second voltage and the first current limiting value is greater than the second current limiting value.

2. The voltage regulation circuit as described in claim 1, characterized in that, The voltage regulation unit includes: a first resistor, a second resistor, a first current source, an overcurrent protection comparator, an error amplifier, a current sensor, a power transistor, a first sampling resistor, and a second sampling resistor, wherein: The first resistor has a first voltage input at its first end and its second end is coupled to the first input end of the overcurrent protection comparator and the first end of the first current source. The second resistor has the first voltage input at its first end and its second end coupled to the second input end of the overcurrent protection comparator and the first end of the current sensor. The first current source has its second terminal grounded. The overcurrent protection comparator has its output terminal coupled to the gate of the power transistor. The error amplifier has a first input terminal coupled between the second terminal of the first sampling resistor and the first terminal of the second sampling resistor, a first reference voltage input at its second input terminal, and an output terminal coupled to the gate of the power transistor. The power transistor has the first voltage input at its source and is coupled to the second terminal of the current sensor, and its drain is coupled to the first terminal of the first sampling resistor. The second end of the first sampling resistor is coupled to the first end of the second sampling resistor; The second sampling resistor has its second terminal grounded.

3. The voltage regulation circuit as described in claim 2, characterized in that, The current limiting adjustment unit includes: a current limiting adjustment unit adapted to reduce the current flowing through the first resistor in a stepwise manner to the output current of the first current source during the continuous decrease of the output voltage of the voltage regulation unit.

4. The voltage regulation circuit as described in claim 3, characterized in that, The current limiting adjustment unit includes N adjustment sub-modules; wherein, the i-th adjustment sub-module includes: the i-th second current source, the i-th first switching unit, and the i-th third sampling resistor, wherein: The i-th second current source has its first end coupled to the first end of the first current source, and its second end coupled to the first end of the i-th first switching unit; The second terminal of the i-th first switching unit is coupled to the second terminal of the first current source, and its control terminal is coupled to the second terminal of the i-th third sampling resistor; The i-th third sampling resistor is set in the sampling resistor string, with its first end coupled to the first input terminal of the error amplifier and its second end coupled to the first end of the (i+1)-th third sampling resistor; the sampling resistor string is formed by the first sampling resistor, the second sampling resistor and N third sampling resistors connected in series, with the first end of the sampling resistor string coupled to the output terminal of the voltage regulation circuit and the second end of the sampling resistor string grounded; i is a positive integer and i≤N.

5. The voltage regulation circuit as described in claim 2, characterized in that, The current limiting adjustment unit is adapted to continuously reduce the current flowing through the first resistor to the output current of the first current source during the continuous decrease of the output voltage of the voltage regulation unit.

6. The voltage regulation circuit as described in claim 5, characterized in that, The current limiting adjustment unit includes: an operational amplifier, a third switching unit, and a variable impedance device, wherein: The third switching unit has a first terminal coupled to the first terminal of the first current source, a second terminal coupled to the first terminal of the impedance variable device, and a control terminal coupled to the output terminal of the operational amplifier. The operational amplifier has a second reference voltage input at its first input terminal, and its second input terminal is coupled to the second terminal of the third switching unit and the first terminal of the variable impedance device. The second terminal of the variable impedance device is coupled to the second terminal of the first current source.

7. The voltage regulation circuit as described in claim 6, characterized in that, The impedance value of the variable impedance device changes in a negatively correlated with the output voltage of the voltage regulation unit.

8. The voltage regulation circuit as described in claim 7, characterized in that, The variable impedance device includes a MOSFET, wherein: The MOS transistor has its drain coupled to the second terminal of the third switching unit, its source coupled to the second terminal of the first current source, and its gate coupled to the first terminal of the second sampling resistor.

9. An electronic device, characterized in that, include: The voltage regulation circuit as described in any one of claims 1 to 8.

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