Power management system and chip

Abstract

The invention provides a power management system and a chip, and relates to the technical field of integrated circuits. The power management system comprises a current protection circuit, a sampling module, a control module and a voltage regulation module. The sampling module is used for acquiring an output current of the power management system and converting the output current into a voltage to obtain a sampling voltage; the control module is used for acquiring the sampling voltage and changing the output voltage of the voltage adjusting module according to the sampling voltage so as to adjust the output current of the main power tube through the output voltage; the overcurrent protection circuit is used for determining a control voltage according to the sampling voltage, and limiting the opening degree of the main power tube through the control voltage, so that the output current of the main power tube is smaller than or equal to a preset overcurrent threshold current. On the basis, overcurrent protection can be achieved through a simple circuit combination and by means of the structure of the charging circuit, the monitoring precision is guaranteed, meanwhile, the device cost is reduced, meanwhile, overcurrent protection threshold values of different battery management chips are adapted, and compatibility is improved.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuit technology, and in particular, to a power management system and a chip. Background Art

[0002] In the prior art, the linear charging method is applicable to the power management circuit of a single lithium-ion battery or a low-power device, and can supply power with the same output current under different load voltages through a corresponding power supply circuit. However, due to the large voltage difference between the input voltage and the output voltage of the linear charging method, if a short circuit or a fault occurs in the power supply circuit, a large current is generated in the charging loop, resulting in a high output power and damaging the power supply circuit.

[0003] To avoid the above problems, usually an additional current sampling circuit or a protection loop is introduced in the main power supply loop. Although the loop current can be accurately monitored, it will result in a relatively large chip size and high cost of the power supply circuit.

[0004] Based on this, there is an urgent need for a battery management solution to reduce the device cost while ensuring the monitoring accuracy. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a power management system and a chip, which realize overcurrent protection through a simple circuit combination by using the structure of the charging circuit itself, reduce the device cost while ensuring the monitoring accuracy, and at the same time adapt to the overcurrent protection thresholds of different battery management chips, improving the compatibility.

[0006] In a first aspect, the present invention provides a power management system, including: an overcurrent protection circuit, a sampling module, a control module, and a voltage adjustment module; the input end of the overcurrent protection circuit is connected to the output end of the sampling module; the output end of the overcurrent protection circuit is connected to the output end of the voltage adjustment module; the output end of the sampling module is also connected to the input end of the control module; the output end of the control module is connected to the input end of the voltage adjustment module;

[0007] The sampling module is configured to obtain the output current of the power management system and convert the output current into a voltage to obtain a sampling voltage;

[0008] The control module is configured to obtain and change the output voltage of the voltage adjustment module according to the sampling voltage to adjust the output current of the main power tube through the output voltage;

[0009] The overcurrent protection circuit is configured to determine a control voltage according to the sampling voltage and limit the opening degree of the main power tube through the control voltage so that the output current of the main power tube is less than or equal to a preset overcurrent threshold current.

[0010] Optionally, the overcurrent protection circuit includes a converter and an overcurrent threshold discriminator;

[0011] The converter is respectively connected to the sampling module and the overcurrent threshold discriminator;

[0012] The converter is used to convert the sampled voltage into a control voltage;

[0013] The overcurrent threshold discriminator is used to change the output voltage of the voltage adjustment module and limit the turn-on degree of the main power transistor when the control voltage is greater than the reference voltage.

[0014] Optionally, when the converter includes a conversion resistor and a first transimpedance amplifier, the overcurrent protection circuit further includes a variable resistor; the first end of the conversion resistor is connected to the output end of the sampling module and the first input end of the first transimpedance amplifier; the second end of the conversion resistor is connected to the second input end of the first transimpedance amplifier and the input end of the control module; the output end of the first transimpedance amplifier is connected to the first end of the variable resistor and the control end of the overcurrent threshold discriminator.

[0015] Optionally, the overcurrent threshold discriminator includes a first switching transistor, the control end of the first switching transistor is connected to the output end of the first transimpedance amplifier; the first end of the first switching transistor is grounded; the second end of the first switching transistor is connected to the output end of the voltage adjustment module;

[0016] Taking the threshold voltage of the first switching transistor as the reference voltage, when the control voltage is greater than the threshold voltage of the first switching transistor, the first switching transistor conducts, pulling down the output voltage of the voltage adjustment module, so that the output current of the main power transistor is less than or equal to the preset overcurrent threshold current.

[0017] Optionally, when the overcurrent threshold discriminator includes a second transimpedance amplifier, the output end of the second transimpedance amplifier is connected to the output end of the voltage adjustment module; the first input end of the second transimpedance amplifier is connected to the output end of the first transimpedance amplifier; the second input end of the second transimpedance amplifier is used to receive the reference voltage;

[0018] When the control voltage is greater than the reference voltage, the second transimpedance amplifier outputs a low-level signal, pulling down the output voltage of the voltage adjustment module, so that the output current of the main power transistor is less than or equal to the preset overcurrent threshold current.

[0019] Optionally, the power management system further includes a first resistor; the first end of the first resistor is connected to the input end of the control module and the second end of the conversion resistor; the second end of the first resistor is grounded.

[0020] Optionally, when the voltage adjustment module includes a second switching transistor, the control end of the second switching transistor is connected to the output end of the control module; the first end of the second switching transistor serves as the output end of the voltage adjustment module and is connected to the output end of the overcurrent protection circuit; the second end of the second switching transistor is grounded.

[0021] Optionally, the sampling module includes a sampling power transistor, and the control terminal of the sampling power transistor is connected to the control terminal of the main power transistor; the first terminal of the sampling power transistor serves as the output terminal of the sampling module and is connected to the converter; the first terminal of the sampling power transistor is connected to the first terminal of the main power transistor.

[0022] Optionally, the calculation formula of the preset overcurrent threshold current satisfies:

[0023]

[0024] wherein, I OCTH is the preset overcurrent threshold current value; R sense is the resistance value of the conversion resistor in the overcurrent protection circuit; g m is the transresistance coefficient in the overcurrent protection circuit; VTH is the threshold voltage in the overcurrent protection circuit; N is the area ratio of the main power transistor and the sampling power transistor in the sampling module; R a is the resistance value of the adjustable resistor in the overcurrent protection circuit.

[0025] In a second aspect, the present invention further provides a power management chip, including the overcurrent protection circuit according to any one of the above first aspects.

[0026] A power management system and chip provided by the present invention include: an overcurrent protection circuit, a sampling module, a control module, and a voltage adjustment module. Among them, the sampling module is used to obtain the output current of the power management system, convert the output current into a voltage to obtain a sampling voltage, and then the control module obtains and changes the output voltage of the voltage adjustment module according to the sampling voltage to adjust the output current of the main power transistor. The overcurrent protection circuit determines the control voltage according to the sampling voltage and limits the opening degree of the main power transistor through the control voltage, so that the output current of the main power transistor is less than or equal to the preset overcurrent threshold current. Based on this, the power management system and chip provided by the present invention can achieve overcurrent protection by using the structure of the charging circuit itself through a simple circuit combination, reduce the device cost while ensuring the monitoring accuracy, and adapt to the overcurrent protection thresholds of different battery management chips, improving the compatibility.

[0027] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following specifically enumerates preferred embodiments and, in conjunction with the accompanying drawings, makes the following detailed description. Description of the Drawings

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 FIG. 1 shows one of the schematic structural diagrams of the power management system provided by an embodiment of the present invention;

[0030] Figure 2 FIG. 2 shows another schematic structural diagram of the power management system provided by an embodiment of the present invention;

[0031] Figure 3 FIG. 3 shows the schematic structural diagram of the overcurrent protection circuit in an embodiment of the present invention;

[0032] Figure 4 FIG. 4 shows one of the circuit schematic diagrams of the overcurrent protection circuit in an embodiment of the present invention;

[0033] Figure 5 FIG. 5 shows another circuit schematic diagram of the overcurrent protection circuit in an embodiment of the present invention;

[0034] Figure 6 FIG. 6 shows the third circuit schematic diagram of the overcurrent protection circuit in an embodiment of the present invention;

[0035] Figure 7 FIG. 7 shows one of the circuit schematic diagrams of the power management system provided by an embodiment of the present invention;

[0036] Figure 8 FIG. 8 shows another circuit schematic diagram of the power management system provided by an embodiment of the present invention.

[0037] Description of main component symbols: 10 - power management system; 101 - control module; 102 - overcurrent protection circuit; 103 - voltage adjustment module; 104 - sampling module; 201 - converter; 202 - overcurrent threshold discriminator; Q1 - main power transistor; Q2 - sampling power transistor; Q3 - first switching transistor; Q4 - second switching transistor; R1 - conversion resistor; R2 - adjustable resistor; R3 - first resistor; G1 - first transimpedance amplifier; G2 - second transimpedance amplifier. Detailed Embodiments

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, but not all, of the embodiments of the present invention. Components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present invention provided herein is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0039] As described in the background art, in general, the linear charging method will adopt an additional current sampling circuit or introduce a protection loop in the main power supply loop to avoid the danger caused by overcurrent. Although this method can accurately monitor the loop current, it will increase the chip size of the power supply circuit.

[0040] Based on this, the present invention provides a power management solution to avoid the above technical problems.

[0041] Please refer to Figure 1 , Figure 1 , which shows one of the structural schematic diagrams of the power management system in the present invention. The present invention provides a power management system 10, including: an overcurrent protection circuit 102, a sampling module 104, a control module 101, and a voltage adjustment module 103. Among them, the input end of the overcurrent protection circuit 102 is connected to the output end of the sampling module 104; the output end of the overcurrent protection circuit 102 is connected to the output end of the voltage adjustment module 103; the output end of the sampling module 104 is also connected to the input end of the control module 101; the output end of the control module 101 is connected to the input end of the voltage adjustment module 103.

[0042] In this embodiment, the sampling module 104 is used to obtain the output current of the power management system 10 and convert the output current into a voltage to obtain a sampling voltage.

[0043] The control module 101 is used to obtain and change the output voltage of the voltage adjustment module 103 according to the sampling voltage, so as to adjust the output current of the main power transistor Q1 through the output voltage.

[0044] The overcurrent protection circuit 102 is used to determine the control voltage according to the sampling voltage and limit the opening degree of the main power transistor Q1 through the control voltage, so that the output current of the main power transistor Q1 is less than or equal to the preset overcurrent threshold current.

[0045] In this embodiment, the sampling module 104 obtains the output current of the main power transistor Q1 and sends the output current to the control module 101. The control module 101 then changes the output voltage of the voltage adjustment module 103 according to the output current, and further changes the opening degree of the main power transistor Q1 through the output voltage, and then changes the output voltage of the main power transistor Q1.

[0046] In a possible implementation manner, the output voltage of the voltage adjustment module 103 can change the gate voltage of the main power transistor Q1, and further adjust the opening degree of the main power transistor Q1 through the gate voltage to change the output voltage of the main power transistor Q1. For example, when the output current of the main power transistor Q1 increases, the detected current obtained by the sampling module 104 will also increase. If the output current of the main power transistor Q1 exceeds the preset value V ref1When this happens, the control module 101 will send a control signal to the adjustment module, such as increasing the gate voltage of the switching transistor in the adjustment module, making the opening degree of the switching transistor larger, thereby changing the output voltage of the adjustment module, and then making the gate voltage of the main power transistor Q1 decrease as the opening degree of the switching transistor in the adjustment module becomes larger, and then reducing the output current of the main power transistor Q1. This process is the normal adjustment process of the power management system in this embodiment.

[0047] Please, on the basis of Figure 1 , refer to Figure 2 , Figure 2 which shows the second schematic diagram of the structure of the power management system in this embodiment; the power management system 10 in this embodiment further includes a first resistor R3; the first end of the first resistor R3 is connected to the input end of the control module 101 and the first end of the overcurrent protection circuit 102; the second end of the first resistor R3 is grounded.

[0048] Based on this, during the normal adjustment process of the power management system 10, taking I OUT-Normal as the conventional output current of the power management system 10 in the present invention, the calculation formula of this conventional output current I OUT-Normal can be expressed as:

[0049]

[0050] In the formula, N is the area ratio of the main power transistor Q1 and the sampling power transistor in the sampling module 104, that is, the ratio between the output current I OUT of the main power transistor Q1 and the sampling current I sense ; R SET is the resistance value of the first resistor R3.

[0051] To avoid the short - circuit situation of the battery management system, an overcurrent protection circuit 102 can be added on the basis of the above - mentioned architecture. On the basis of the sampling module 104 obtaining the output current of the main power transistor Q1, according to this output current, the control voltage is determined to adjust the output voltage of the voltage adjustment module 103, so as to achieve the purpose of restricting the opening degree of the main power transistor Q1, and then making the output current of the main power transistor Q1 less than or equal to the preset over - current threshold current.

[0052] In this embodiment, the overcurrent protection circuit 102 can determine whether there is an over - current situation in the power management system in the current state by judging whether the output current of the main power transistor Q1 is greater than the preset threshold. If so, it adjusts the output voltage of the voltage adjustment module 103.

[0053] In a possible implementation manner, please, on the basis of Figure 2 , refer to Figure 3 , Figure 3The structural schematic diagram of the overcurrent protection circuit in the present invention is shown. In this embodiment, the overcurrent protection circuit 102 includes a converter 201 and an overcurrent threshold discriminator 202; the converter 201 is respectively connected to the sampling module 104 and the overcurrent threshold discriminator 202.

[0054] In this embodiment, the converter 201 is used to convert the sampling voltage into a control voltage.

[0055] The overcurrent threshold discriminator 202 is used to change the output voltage of the voltage adjustment module 103 and limit the turn-on degree of the main power transistor Q1 when the control voltage is greater than the reference voltage.

[0056] Please, on the basis of Figure 3 , refer to Figure 4 , Figure 4 One of the circuit schematic diagrams of the overcurrent protection circuit 102 in this embodiment is shown. When the converter 201 includes a conversion resistor R1 and a first transimpedance amplifier G1, the overcurrent protection circuit 102 further includes a variable resistor R2; the first end of the conversion resistor R1 is connected to the output end of the sampling module 104 and the first input end of the first transimpedance amplifier G1; the second end of the conversion resistor R1 is connected to the second input end of the first transimpedance amplifier G1 and the input end of the control module 101; the output end of the first transimpedance amplifier G1 is connected to the first end of the variable resistor R2 and the control end of the overcurrent threshold discriminator 202.

[0057] The implementation manner of the overcurrent threshold discriminator 202 is not limited in this embodiment.

[0058] Embodiment 1

[0059] In a possible implementation manner, please, on the basis of Figure 4 , refer to Figure 5 , Figure 5 Another circuit schematic diagram of the overcurrent protection circuit 102 in the present invention is shown. The overcurrent threshold discriminator 202 includes a first switching transistor Q3, the control end of the first switching transistor Q3 is connected to the output end of the first transimpedance amplifier G1; the first end of the first switching transistor Q3 is grounded; the second end of the first switching transistor Q3 is connected to the output end of the voltage adjustment module 103.

[0060] In this embodiment, taking the threshold voltage of the first switching transistor Q3 as the reference voltage Vref, when the control voltage is greater than the threshold voltage of the first switching transistor Q3, the first switching transistor Q3 conducts, pulling down the output voltage of the voltage adjustment module 103, so that the output current of the main power transistor Q1 is less than or equal to the preset overcurrent threshold current.

[0061] Embodiment 2

[0062] In another possible implementation manner, please, on the basis of Figure 4 , refer to Figure 6, Figure 6 FIG. 3 shows the schematic circuit diagram of the overcurrent protection circuit 102 in the present invention. When the overcurrent threshold discriminator 202 includes the second transimpedance amplifier G2, the output terminal of the second transimpedance amplifier G2 is connected to the output terminal of the voltage adjustment module 103; the first input terminal of the second transimpedance amplifier G2 is connected to the output terminal of the first transimpedance amplifier G1; the second input terminal of the second transimpedance amplifier G2 is used to receive the reference voltage Vref.

[0063] In this embodiment, when the control voltage is greater than the reference voltage Vref, the second transimpedance amplifier G2 outputs a low-level signal, pulling down the output voltage of the voltage adjustment module 103, so that the output current of the main power transistor Q1 is less than or equal to the preset overcurrent threshold current.

[0064] For the two implementation manners provided in this embodiment, the sampling module 104 can convert the output current of the main power transistor Q1 into a control voltage, and when it is detected that the control voltage exceeds the reference voltage Vref, that is, when the current power management system 10 is in an overcurrent state, the output voltage of the voltage adjustment module 103 is pulled down, so that the output current of the main power transistor Q1 is less than or equal to the preset overcurrent threshold current.

[0065] Furthermore, in order to ensure that the overcurrent protection circuit 102 does not affect the control of the normal charging function by the control module 101, in this embodiment, the relevant parameters of each device in the overcurrent protection circuit 102 can be reasonably set to ensure that the threshold for triggering overcurrent is higher than the actual charging current range, and at the same time limit the maximum output current value. The calculation formula for the preset overcurrent threshold current in this embodiment satisfies:

[0066]

[0067] Among them, I OCTH is the preset overcurrent threshold current value; R sense is the resistance value of the conversion resistor R1 in the overcurrent protection circuit 102; g m is the transimpedance coefficient in the overcurrent protection circuit 102; VTH is the threshold voltage in the overcurrent protection circuit 102, which is numerically equal to the above parameter voltage Vref; R a is the resistance value of the adjustable resistor R2 in the overcurrent protection circuit 102.

[0068] Taking Embodiment 1 as an example, the threshold voltage VTH in the overcurrent protection circuit 102 is the threshold voltage of the first switching transistor Q3. When the first switching transistor Q3 is an NMOS, the numerical value of the threshold voltage VTH in the overcurrent protection circuit 102 can be equal to VTH NMOS3 . When the overcurrent protection is triggered, at this time I OCTH = I OUT , I OUTRepresenting the output current of the power management system 10 in the present invention, it should be noted that the preset overcurrent threshold current value I in the present invention OCTH needs to be greater than the conventional output current I OUT-Normal .

[0069] In a possible implementation manner, the adjustment of I can be achieved by adjusting the resistance value of the adjustable resistor R2 in the overcurrent protection circuit 102 OCTH so that there is only one low-frequency pole in the entire loop and it is higher than the main pole of the main loop.

[0070] Based on this, the circuit provided by the embodiment of the present invention will be much smaller than the impedance of the current mirror output in the linear charging method, and ensure the stability of the circuit without complex loop compensation. At the same time, ensure that the bandwidth of the overcurrent protection circuit 102 is higher than the bandwidth of the main loop, so that the circuit structure in the present invention will be much smaller than the conventional power supply system with the overcurrent protection circuit 102 (that is, the power supply system with the additional current sampling circuit mentioned above).

[0071] In addition, due to the possible deviation of the current sampling ratio of the actual chips corresponding to different battery management systems, and at the same time, the threshold voltage of the first switching transistor Q3 is affected by temperature and process fluctuations, some high-precision overcurrent protection circuits 102 will introduce additional error amplifiers. Since the high-precision circuit itself has a large gain and may have internal low-frequency poles, the loop stability compensation of the overcurrent protection circuit 102 becomes complicated and may require additional Miller capacitors, further increasing the cost. To overcome the above problems, the present invention can adjust the size of the adjustable resistor R2 according to the actual situation through trimming of the analog hybrid integrated circuit to ensure that different chips can have a close overcurrent protection threshold current I OCTH ; compared with the complex additional analog circuit, the circuit complexity of the analog hybrid integrated circuit is low and the cost is low, which can further reduce the device structure and cost of this embodiment.

[0072] To ensure the stability of the circuit structure, in a possible implementation manner, please refer to Figure 4 on the basis of Figure 7 , Figure 7 Fig. shows one of the circuit schematic diagrams of the power management system 10 in the present invention. In the embodiment of the present invention, the voltage adjustment module 103 includes a second switching transistor Q4. The control end of the second switching transistor Q4 is connected to the output end of the control module 101; the first end of the second switching transistor Q4 is used as the output end of the voltage adjustment module 103 and is connected to the output end of the overcurrent protection circuit 102; the second end of the second switching transistor Q4 is grounded.

[0073] Please continue to refer to Figure 7, in the embodiment of the present invention, the sampling module 104 includes a sampling power transistor Q2, and the control end of the sampling power transistor Q2 is connected to the control end of the main power transistor Q1; the first end of the sampling power transistor Q2 serves as the output end of the sampling module 104 and is connected to the converter 201; the first end of the sampling power transistor Q2 is connected to the first end of the main power transistor Q1.

[0074] It should be noted that the above implementation manner is only an exemplary illustration taking Embodiment 1 as an example, and the above adjustment manner and setting manner are also applicable to Embodiment 2. On this basis, it can be further Figure 6 On the basis of, refer to Figure 8 , Figure 8 FIG. 2 shows the second circuit schematic diagram of the power management system in the present invention. The corresponding technical principles and related descriptions are not repeated here, and reference can be made to Embodiment 1.

[0075] In summary, a power management system provided by the present invention includes: an overcurrent protection circuit, a sampling module, a control module, and a voltage adjustment module. Among them, the sampling module is used to obtain the output current of the power management system, convert the output current into a voltage to obtain a sampling voltage, and then the control module obtains and changes the output voltage of the voltage adjustment module according to the sampling voltage to adjust the output current of the main power transistor. The overcurrent protection circuit determines the control voltage according to the sampling voltage, and limits the opening degree of the main power transistor through the control voltage, so that the output current of the main power transistor is less than or equal to the preset overcurrent threshold current.

[0076] Based on this, the power management system and chip provided by the present invention can realize overcurrent protection by using the structure of the charging circuit itself through a simple circuit combination, reduce the device cost while ensuring the monitoring accuracy, and at the same time adapt to the overcurrent protection thresholds of different battery management chips, improving the compatibility.

[0077] With the same idea as the previous embodiment, the present invention also provides a power management chip, including the overcurrent protection circuit described in any item of the first aspect above, which can realize overcurrent protection by using the structure of the charging circuit itself through a simple circuit combination, reduce the device cost while ensuring the monitoring accuracy, and at the same time adapt to the overcurrent protection thresholds of different battery management chips, improving the compatibility.

[0078] It should be noted that: similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0079] In the description of the present invention, it should be noted that the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0080] In the description of the present invention, it should also be noted that, unless otherwise clearly specified and defined, the terms "arranged" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0081] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions recorded in the foregoing embodiments or can easily think of changes, or perform equivalent replacements on some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. All should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A power management system, characterized in that, Including: An overcurrent protection circuit, a sampling module, a control module, and a voltage adjustment module; The input end of the overcurrent protection circuit is connected to the output end of the sampling module; the output end of the overcurrent protection circuit is connected to the output end of the voltage adjustment module; the output end of the sampling module is also connected to the input end of the control module; the output end of the control module is connected to the input end of the voltage adjustment module; The sampling module is configured to obtain the output current of the power management system and convert the output current into a voltage to obtain a sampling voltage; The control module is configured to obtain and change the output voltage of the voltage adjustment module according to the sampling voltage, so as to change the output current of the main power transistor through the output voltage; The overcurrent protection circuit is configured to determine a control voltage according to the sampling voltage and limit the opening degree of the main power transistor through the control voltage, so that the output current of the main power transistor is less than or equal to a preset overcurrent threshold current.

2. The power management system according to claim 1, wherein The overcurrent protection circuit includes a converter and an overcurrent threshold discriminator; The converter is respectively connected to the sampling module and the overcurrent threshold discriminator; The converter is configured to convert the sampling voltage into the control voltage; The overcurrent threshold discriminator is configured to change the output voltage of the voltage adjustment module and limit the opening degree of the main power transistor when the control voltage is greater than a reference voltage.

3. The power management system according to claim 2, wherein When the converter includes a conversion resistor and a first transimpedance amplifier, the overcurrent protection circuit further includes a variable resistor; the first end of the conversion resistor is connected to the output end of the sampling module and the first input end of the first transimpedance amplifier; the second end of the conversion resistor is connected to the second input end of the first transimpedance amplifier and the input end of the control module; the output end of the first transimpedance amplifier is connected to the first end of the variable resistor and the control end of the overcurrent threshold discriminator.

4. The power management system according to claim 3, wherein, The overcurrent threshold discriminator includes a first switching transistor, the control end of the first switching transistor is connected to the output end of the first transimpedance amplifier; the first of the first switching transistor is grounded; the second end of the first switching transistor is connected to the output end of the voltage adjustment module; Taking the threshold voltage of the first switching transistor as the reference voltage, when the control voltage is greater than the threshold voltage of the first switching transistor, the first switching transistor conducts, pulling down the output voltage of the voltage adjustment module, so that the output current of the main power transistor is less than or equal to a preset overcurrent threshold current.

5. The power management system according to claim 3, characterized in that, When the overcurrent threshold discriminator includes a second transimpedance amplifier, the output end of the second transimpedance amplifier is connected to the output end of the voltage adjustment module; the first input end of the second transimpedance amplifier is connected to the output end of the first transimpedance amplifier; the second input end of the second transimpedance amplifier is used to receive a reference voltage; When the control voltage is greater than the reference voltage, the second transimpedance amplifier outputs a low-level signal, pulling down the output voltage of the voltage adjustment module, so that the output current of the main power transistor is less than or equal to a preset overcurrent threshold current.

6. The power management system according to claim 3, wherein The power management system further includes a first resistor; a first end of the first resistor is connected to an input end of the control module and a second end of the conversion resistor; a second end of the first resistor is grounded.

7. The power management system according to claim 2, characterized in that, When the voltage adjustment module includes a second switching tube, a control end of the second switching tube is connected to an output end of the control module; a first end of the second switching tube serves as an output end of the voltage adjustment module and is connected to an output end of the overcurrent protection circuit; a second end of the second switching tube is grounded.

8. The power management system according to claim 2, wherein The sampling module includes a sampling power tube, a control end of the sampling power tube is connected to a control end of the main power tube; a first end of the sampling power tube serves as an output end of the sampling module and is connected to the converter; the first end of the sampling power tube is connected to a first end of the main power tube.

9. The power management system according to claim 1, characterized in that The calculation formula of the preset overcurrent threshold current satisfies: Wherein, I OCTH is the preset overcurrent threshold current value; R sense is the resistance value of the conversion resistor in the overcurrent protection circuit; g m is the transresistance coefficient in the overcurrent protection circuit; VTH is the threshold voltage in the overcurrent protection circuit; N is the area ratio of the main power transistor to the sampling power transistor in the sampling module; R a is the resistance value of the adjustable resistor in the overcurrent protection circuit.

10. A power management chip, characterized in that, Including the overcurrent protection circuit according to any one of claims 1-9.

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