A power supply circuit with a current limiting function

Abstract

The present invention relates to the technical field of power supply circuits, and particularly relates to a power supply circuit with a current limiting function. In the present invention, a power supply circuit, a first current source circuit, a current limiting circuit, and an output circuit are provided. The power supply circuit and the first current source circuit are used to provide the electrical signals required for the operation of the current limiting circuit and the output circuit. The output circuit can output a stable electrical signal to supply power to an external load. At the same time, when a fault occurs in the circuit causing the output current of the output circuit to be large, the current limiting circuit can change the working state of the output circuit, reduce the output current, and after the fault is eliminated, restore the working state of the output circuit to make it work normally. Thus, the power supply circuit can achieve automatic current limiting and automatic recovery after current limiting. At the same time, two low-voltage power supplies are generated by one power supply circuit, so that the chip volume can be reduced, which conforms to the development trend of miniaturization of integrated circuit control chips.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply circuits, and particularly to a power supply circuit with a current limiting function. Background Art

[0002] At present, in an integrated circuit control chip, stable and reliable power supply inside the chip is one of the key factors to ensure the normal operation of the chip. With the continuous development of electronic technology, the functions of control chips are becoming increasingly complex, and the requirements for the internal power supply circuit of the chip are also getting higher and higher.

[0003] In many actual application scenarios, the power supply circuit may face various abnormal situations, such as sudden changes in load, short circuit faults, etc. These situations may cause the current of the power supply circuit to increase sharply instantaneously. Excessive current will not only damage the power supply circuit, shorten its service life, but may even cause serious problems such as overheating and burning of other devices inside the chip, thereby affecting the stability and reliability of the entire integrated circuit control chip, resulting in adverse consequences such as shutdown of the external circuit of the chip and data loss.

[0004] The structure of the traditional power supply circuit with a current limiting function inside the chip is relatively complex. It not only has problems such as low current limiting accuracy and inability to automatically recover, but also requires multiple low-voltage power supplies generated by the internal power supply circuit of the chip. And for several low-voltage power supplies, several internal power supply circuits need to be set in the power supply circuit, resulting in an increase in the volume of the power supply circuit, which does not conform to the development trend of miniaturization of integrated circuit control chips. Summary of the Invention

[0005] In view of this, an embodiment of the present invention provides a power supply circuit with a current limiting function to solve the technical problems of low current limiting accuracy, inability to automatically recover, and large volume existing in the current limiting method used in the power supply circuit in the prior art.

[0006] The technical solution provided by the embodiment of the present invention is as follows:

[0007] A first aspect of an embodiment of the present invention provides a power supply circuit with a current limiting function, including: a power supply circuit, a first current source circuit, a current limiting circuit, and an output circuit;

[0008] The first end of the power supply circuit is connected to an external power supply, the second end of the power supply circuit is grounded, the third end of the power supply circuit is connected to the first end of the first current source circuit, the first end of the current limiting circuit, and the first end of the output circuit, the fourth end of the power supply circuit is connected to the second end of the current limiting circuit and the second end of the output circuit, and the power supply circuit is used to generate a first low-voltage power supply and a second low-voltage power supply simultaneously after the external power supply is connected;

[0009] The second terminal of the first current source circuit is connected to the third terminal of the current limiting circuit and the third terminal of the output circuit. The third terminal of the first current source circuit is grounded. The first current source circuit is used to conduct and work according to the first low-voltage power supply.

[0010] The fourth terminal of the current limiting circuit is connected to an external power supply. The fifth terminal of the current limiting circuit is connected to the fourth terminal of the output circuit. The sixth terminal of the current limiting circuit is connected to the fifth terminal of the output circuit. The seventh terminal of the current limiting circuit is grounded. The current limiting circuit is used to conduct and work according to the external power supply, the first low-voltage power supply, the second low-voltage power supply, and the first current source circuit that is conducting and working, and is in the first working state.

[0011] The sixth terminal of the output circuit is connected to an external power supply. The seventh terminal of the output circuit is connected to the output terminal of the power supply circuit. The eighth terminal of the output circuit is grounded. The output circuit is used to conduct and work according to the external power supply, the first low-voltage power supply, the second low-voltage power supply, and the first current source circuit that is conducting and working, and is in the second working state, and stabilizes the voltage at the output terminal of the power supply circuit at a first preset value.

[0012] When the output current of the output circuit is greater than a second preset value, the current limiting circuit switches from the first working state to the third working state according to the second low-voltage power supply and the current in the output circuit that is greater than the second preset value, and causes the output circuit to switch from the second working state to the fourth working state, then the output current of the output circuit decreases. When the output current of the output circuit is less than the second preset value, the current limiting circuit returns to the first working state according to the second low-voltage power supply and the current in the output circuit that is less than the second preset value, and causes the output circuit to return to the second working state, and stabilizes the voltage at the output terminal of the power supply circuit at the first preset value.

[0013] In an alternative embodiment, the first current source circuit includes: a first current source and a first resistor. One end of the first current source is connected to one end of the first resistor, the third terminal of the current limiting circuit, and the third terminal of the output circuit. The other end of the first current source is grounded. The other end of the first resistor is connected to the third terminal of the power supply circuit, the first terminal of the current limiting circuit, and the first terminal of the output circuit.

[0014] In an alternative embodiment, the current limiting circuit includes: a first controllable current source, a second controllable current source, a fifth controllable current source, a seventh controllable current source, a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a second resistor, a fourth resistor, and a tenth resistor.

[0015] The positive control terminal and the input terminal of the first controllable current source are connected to the positive control terminal and the input terminal of the second controllable current source, the first terminal of the third switching transistor, the third terminal of the power supply circuit, the first terminal of the first current source circuit, and the first terminal of the output circuit. The negative control terminal of the first controllable current source is connected to the negative control terminal of the second controllable current source, the second terminal of the first current source circuit, and the third terminal of the output circuit. The output terminal of the first controllable current source is connected to the first terminal of the first switching transistor and the first terminal of the second switching transistor. The second terminal of the first switching transistor is connected to the fourth terminal of the power supply circuit and the second terminal of the output circuit. The third terminal of the first switching transistor is connected to one end of the second resistor and the positive control terminal of the fifth controllable current source. The second terminal of the second switching transistor is connected to the output terminal of the seventh controllable current source and one end of the tenth resistor. The third terminal of the second switching transistor and the other end of the second resistor are grounded;

[0016] The output terminal of the second controllable current source is connected to the second terminal of the third switching transistor and the input terminal of the fifth controllable current source. The third terminal of the third switching transistor is connected to the first terminal of the fourth switching transistor and one end of the fourth resistor. The negative control terminal and the output terminal of the fifth controllable current source, the other end of the fourth resistor, the other end of the tenth resistor, and the second terminal of the fourth switching transistor are grounded. The third terminal of the fourth switching transistor is connected to the fourth terminal of the output circuit. The positive control terminal and the input terminal of the seventh controllable current source are connected to an external power supply. The negative control terminal of the seventh controllable current source is connected to the fifth terminal of the output circuit.

[0017] In an alternative embodiment, the current limiting circuit further includes a third resistor. One end of the third resistor is connected to the third terminal of the second switching transistor, and the other end of the third resistor is grounded. The resistance value of the third resistor is equal to the resistance value of the second resistor.

[0018] In an alternative embodiment, the output circuit includes a third controllable current source, a fourth controllable current source, a sixth controllable current source, an eighth controllable current source, a fifth switching transistor, a sixth switching transistor, a seventh switching transistor, a fifth resistor, a seventh resistor, an eighth resistor, a ninth resistor, and an eleventh resistor;

[0019] The positive control terminal and the input terminal of the third controllable current source are connected to the positive control terminal and the input terminal of the fourth controllable current source, the third terminal of the power supply circuit, the first terminal of the first current source circuit, and the first terminal of the current limiting circuit. The negative control terminal of the third controllable current source is connected to the negative control terminal of the fourth controllable current source, the second terminal of the first current source circuit, and the third terminal of the current limiting circuit. The output terminal of the third controllable current source is connected to the first terminal of the fifth switching transistor and the first terminal of the sixth switching transistor. The second terminal of the fifth switching transistor is connected to the fourth terminal of the power supply circuit and the second terminal of the current limiting circuit. The third terminal of the fifth switching transistor is connected to one end of the fifth resistor and the positive control terminal of the sixth controllable current source. The second terminal of the sixth switching transistor is connected to one end of the ninth resistor and one end of the eleventh resistor. The third terminal of the sixth switching transistor and the other end of the fifth resistor are grounded;

[0020] The output terminal of the fourth controllable current source is connected to the first terminal of the seventh switching transistor, the input terminal of the sixth controllable current source, and the fifth terminal of the current limiting circuit. The second terminal of the seventh switching transistor is connected to one end of the eighth resistor, the negative control terminal of the eighth controllable current source, and the sixth terminal of the current limiting circuit. The third terminal of the seventh switching transistor is connected to one end of the seventh resistor. The negative control terminal and the output terminal of the sixth controllable current source, the other end of the seventh resistor, and the other end of the eleventh resistor are grounded. The other end of the eighth resistor is connected to the positive control terminal and the input terminal of the eighth controllable current source and an external power supply. The output terminal of the eighth controllable current source is connected to the other end of the ninth resistor and the output terminal of the power supply circuit.

[0021] In an alternative embodiment, the third terminal of the power supply circuit outputs a first low-voltage power supply, the fourth terminal of the power supply circuit outputs a second low-voltage power supply, the voltage of the first low-voltage power supply is greater than the voltage of the second low-voltage power supply, and the difference between the voltage of the first low-voltage power supply and the voltage of the second low-voltage power supply is greater than the threshold voltages of the first switching transistor and the fifth switching transistor.

[0022] In an alternative embodiment, the output circuit further includes a sixth resistor. One end of the sixth resistor is connected to the third terminal of the sixth switching transistor, and the other end of the sixth resistor is grounded. The resistance value of the sixth resistor is the same as the resistance value of the fifth resistor.

[0023] In an alternative embodiment, the ratio of the first controllable current generated by the first controllable current source to the second controllable current generated by the second controllable current source is two to one, and the ratio of the third controllable current generated by the third controllable current source to the fourth controllable current generated by the fourth controllable current source is two to one.

[0024] In an alternative embodiment, the power supply circuit further includes: an isolation circuit, a first end of the isolation circuit is connected to one end of the eighth resistor, a negative control end of the seventh controllable current source, and a negative control end of the eighth controllable current source, a second end of the isolation circuit is connected to a third end of the power supply circuit, a first end of the first current source circuit, a first end of the current limiting circuit, and a first end of the output circuit, a third end of the isolation circuit is connected to a second end of the seventh switching tube, a fourth end of the isolation circuit is connected to an output end of the seventh controllable current source, a fifth end of the isolation circuit is connected to a second end of the second switching tube and one end of the tenth resistor, a sixth end of the isolation circuit is grounded, a seventh end of the isolation circuit is connected to an output end of the eighth controllable current source, the other end of the ninth resistor, and an output end of the power supply circuit.

[0025] In an alternative embodiment, the isolation circuit includes an eighth switching tube, a ninth controllable current source, a twelfth resistor, and a thirteenth resistor; a first end of the eighth switching tube is connected to one end of the eighth resistor, a negative control end of the seventh controllable current source, and a negative control end of the eighth controllable current source, a second end of the eighth switching tube is connected to a third end of the power supply circuit, a first end of the first current source circuit, a first end of the current limiting circuit, and a first end of the output circuit, a third end of the eighth switching tube is connected to a second end of the seventh switching tube, an input end of the ninth controllable current source is connected to an output end of the seventh controllable current source, an output end of the ninth controllable current source is connected to a second end of the second switching tube and one end of the tenth resistor, a negative control end of the ninth controllable current source is connected to one end of the thirteenth resistor and one end of the twelfth resistor, the other end of the thirteenth resistor is grounded, a positive control end of the ninth controllable current source is connected to the other end of the twelfth resistor, an output end of the eighth controllable current source, the other end of the ninth resistor, and an output end of the power supply circuit.

[0026] In an alternative embodiment, the current capacity of the ninth controllable current source is greater than the current capacity of the seventh controllable current source.

[0027] The technical solution of the present invention has the following advantages:

[0028] In the present invention, by providing a power supply circuit, a first current source circuit, a current limiting circuit, and an output circuit, the power supply circuit and the first current source circuit are used to provide the electrical signals required for the operation of the current limiting circuit and the output circuit, and the output circuit can output a stable electrical signal to supply power to an external load. At the same time, when a fault occurs in the circuit and the output current of the output circuit is large, the current limiting circuit can change the operating state of the output circuit to reduce the output current, and after the fault is eliminated, the operating state of the output circuit is restored to make it work normally. Thus, the power supply circuit can achieve automatic current limiting and automatic recovery after current limiting. At the same time, by generating two low-voltage power supplies with a single power supply circuit, the chip size can be reduced, which conforms to the development trend of miniaturization of integrated circuit control chips. Moreover, in this embodiment, a power supply circuit is provided in the power supply circuit, and this power supply circuit can output two low-voltage power supplies. Therefore, there is no need to provide multiple internal power supplies. As a result, the space originally used for setting other internal power supplies can be used to set functional structures such as current limiting. This makes a power supply circuit with a current limiting function in this embodiment have a current limiting functional structure on the basis of meeting the chip size design requirements, thereby not only retaining the small size characteristic of the chip but also improving the safety and reliability of the chip.

[0029] In the present invention, through the third resistor and the sixth resistor, it can be ensured that when the circuit is in a stable operating state in the normal output mode, the current and voltage of each path in the output circuit are completely matched, and the gate voltage of the sixth switching transistor is exactly equal to the voltage of the second low-voltage power supply. At the same time, it can be ensured that when the circuit is at the current limiting switching node where it switches from the normal operating mode to the current limiting mode, the gate voltage of the second switching transistor is exactly equal to the voltage of the second low-voltage power supply. Therefore, this power supply circuit can improve the accuracy of the output voltage VOUT and the accuracy of the current limiting switching node, thereby further improving the safety and reliability of the circuit.

[0030] In the present invention, by providing an isolation circuit, all the devices below the isolation circuit can use low-voltage devices, ensuring that the leakage current of the switching transistors is small and improving the safety and reliability of the circuit. Moreover, this isolation circuit prevents the disturbance of the external high-voltage power supply from being conducted to one end of the tenth resistor, thereby ensuring that the current limiting switching node does not drift, and further improving the safety and reliability of the circuit.

[0031] In the present invention, by providing only one power supply circuit, two low-voltage power supplies that are not affected by temperature and have high precision can be generated, thereby improving the output voltage accuracy and current limiting accuracy of this power supply circuit and reducing the volume of this power supply circuit. At the same time, this power supply circuit can provide a first low-voltage power supply with current capacity and a second low-voltage power supply without current capacity. After being reasonably matched with the current limiting circuit and the output circuit, this power supply circuit is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings required for the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0033] Figure 1 It is a structural block diagram of a power supply circuit with a current limiting function in an embodiment of the present invention;

[0034] Figure 2 It is a structural schematic diagram of a power supply circuit with a current limiting function in an embodiment of the present invention;

[0035] Figure 3 It is a structural schematic diagram of another power supply circuit with a current limiting function in an embodiment of the present invention;

[0036] Figure 4 It is a structural block diagram of a power supply circuit in an embodiment of the present invention;

[0037] Figure 5 It is a structural schematic diagram of a power supply circuit in an embodiment of the present invention. Specific Embodiments

[0038] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0039] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0040] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", 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 can also be the communication inside two components. It can be a wireless connection or a wired connection. 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 situations.

[0041] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] An embodiment of the present invention provides a power supply circuit with a current limiting function, as Figure 1 shown. The power supply circuit includes: a power supply circuit 10, a first current source circuit 20, a current limiting circuit 30, and an output circuit 40; a first end of the power supply circuit 10 is connected to an external power supply, a second end of the power supply circuit 10 is grounded, a third end of the power supply circuit 10 is connected to a first end of the first current source circuit 20, a first end of the current limiting circuit 30, and a first end of the output circuit 40. A fourth end of the power supply circuit 10 is connected to a second end of the current limiting circuit 30 and a second end of the output circuit 40. The power supply circuit 10 is used to generate a first low-voltage power supply and a second low-voltage power supply simultaneously after the external power supply is connected. A second end of the first current source circuit 20 is connected to a third end of the current limiting circuit 30 and a third end of the output circuit 40. A third end of the first current source circuit 20 is grounded. The first current source circuit 20 is used to conduct and work according to the first low-voltage power supply.

[0043] A fourth end of the current limiting circuit 30 is connected to the external power supply, a fifth end of the current limiting circuit 30 is connected to a fourth end of the output circuit 40, a sixth end of the current limiting circuit 30 is connected to a fifth end of the output circuit 40, and a seventh end of the current limiting circuit 30 is grounded. The current limiting circuit 30 is used to conduct and work according to the external power supply, the first low-voltage power supply, the second low-voltage power supply, and the first current source circuit 20 that is conducting and working, and is in a first working state. A sixth end of the output circuit 40 is connected to the external power supply, a seventh end of the output circuit 40 is connected to an output end of the power supply circuit, and an eighth end of the output circuit 40 is grounded. The output circuit 40 is used to conduct and work according to the external power supply, the first low-voltage power supply, the second low-voltage power supply, and the first current source circuit 20 that is conducting and working, and is in a second working state to stabilize the voltage at the output end of the power supply circuit at a first preset value.

[0044] When the output current of the output circuit 40 is greater than a second preset value, the current limiting circuit 30 switches from the first working state to the third working state according to the second low-voltage power supply and the current greater than the second preset value in the output circuit 40, and causes the output circuit 40 to switch from the second working state to the fourth working state, so that the output current of the output circuit 40 decreases; when the output current of the output circuit 40 is less than the second preset value, the current limiting circuit 30 returns to the first working state according to the second low-voltage power supply and the current less than the second preset value in the output circuit 40, and causes the output circuit 40 to return to the second working state, stabilizing the voltage at the output end of the power supply circuit at a first preset value.

[0045] Among them, the power supply circuit with current limiting function can be arranged inside the chip. The power supply circuit is a power supply circuit arranged inside the chip, and can also be called an internal power supply. The external power supply is a power supply arranged outside the chip, and the power signal generated by the external power supply is a high-voltage power signal.

[0046] In the present invention, by providing a power supply circuit, a first current source circuit, a current limiting circuit and an output circuit, wherein the power supply circuit and the first current source circuit are used to provide the electrical signals required for the operation of the current limiting circuit and the output circuit, and the output circuit can output a stable electrical signal to supply power to an external load; at the same time, the current limiting circuit can change the working state of the output circuit and reduce the output current when a fault occurs in the circuit and causes the output current of the output circuit to be large, and at the same time, after the fault is eliminated, it restores the working state of the output circuit to make it work normally. Thus, the power supply circuit can achieve automatic current limiting and automatic recovery after current limiting. At the same time, by generating two low-voltage power supplies with one power supply circuit, the chip volume can be reduced, which conforms to the development trend of miniaturization of integrated circuit control chips.

[0047] In addition, in this embodiment, a power supply circuit is provided in the power supply circuit, and the power supply circuit can output two low-voltage power supplies. Therefore, there is no need to provide multiple internal power supplies. Therefore, the space originally used to provide other internal power supplies can be used to provide functional structures such as current limiting. A power supply circuit with current limiting function in this embodiment has a current limiting functional structure on the basis of meeting the chip volume design requirements, thus not only retaining the small volume characteristic of the chip, but also improving the safety and reliability of the chip.

[0048] In an optional implementation manner, as Figure 2As shown, the first current source circuit 20 includes: a first current source I1 and a first resistor R1. One end of the first current source I1 is connected to one end of the first resistor R1, the third end of the current limiting circuit 30, and the third end of the output circuit 40. The other end of the first current source I1 is grounded. The other end of the first resistor R1 is connected to the third end of the power supply circuit (i.e., the internal power supply) 10, the first end of the current limiting circuit 30, and the first end of the output circuit 40. Specifically, when the power supply circuit is powered on, an external power supply is connected to the power supply circuit. The power supply circuit 10 generates a first low-voltage power signal. Thus, a first current is generated in the first current source I1 and flows through the first resistor R1, and a voltage drop is generated across the first resistor R1, that is, the first current source circuit 20 conducts and works.

[0049] In an alternative embodiment, as Figure 2 shown, the output circuit 40 includes a third controllable current source G3, a fourth controllable current source G4, a sixth controllable current source G6, an eighth controllable current source G8, a fifth switching transistor M5, a sixth switching transistor M6, a seventh switching transistor M7, a fifth resistor R5, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and an eleventh resistor R11. The ratio of the third controllable current generated by the third controllable current source G3 to the fourth controllable current generated by the fourth controllable current source G4 is two to one. The third end of the power supply circuit 10 outputs a first low-voltage power supply, and the fourth end of the power supply circuit 10 outputs a second low-voltage power supply. The voltage of the first low-voltage power supply is greater than the voltage of the second low-voltage power supply, and the difference between the voltage of the first low-voltage power supply and the voltage of the second low-voltage power supply is greater than the threshold voltage of the fifth switching transistor M5.

[0050] The positive control terminal and the input terminal of the third controllable current source G3 are connected to the positive control terminal and the input terminal of the fourth controllable current source G4, the third end of the power supply circuit 10, the first end of the first current source circuit 20, and the first end of the current limiting circuit 30. The negative control terminal of the third controllable current source G3 is connected to the negative control terminal of the fourth controllable current source G4, the second end of the first current source circuit, and the third end of the current limiting circuit. The output terminal of the third controllable current source G3 is connected to the first end of the fifth switching transistor M5 and the first end of the sixth switching transistor M6. The second end of the fifth switching transistor M5 is connected to the fourth end of the power supply circuit and the second end of the current limiting circuit. The third end of the fifth switching transistor M5 is connected to one end of the fifth resistor R5 and the positive control terminal of the sixth controllable current source G6. The second end of the sixth switching transistor M6 is connected to one end of the ninth resistor R9 and one end of the eleventh resistor R11. The third end of the sixth switching transistor M6 and the other end of the fifth resistor R5 are grounded;

[0051] The output terminal of the fourth controllable current source G4 is connected to the first terminal of the seventh switching transistor M7, the input terminal of the sixth controllable current source G6, and the fifth terminal of the current limiting circuit. The second terminal of the seventh switching transistor M7 is connected to one end of the eighth resistor R8, the negative control terminal of the eighth controllable current source G8, and the sixth terminal of the current limiting circuit. The third terminal of the seventh switching transistor M7 is connected to one end of the seventh resistor R7. The negative control terminal and the output terminal of the sixth controllable current source G6, the other end of the seventh resistor R7, and the other end of the eleventh resistor R11 are grounded. The other end of the eighth resistor R8 is connected to the positive control terminal and the input terminal of the eighth controllable current source G8 and an external power supply. The output terminal of the eighth controllable current source G8 is connected to the other end of the ninth resistor R9 and the output terminal of the power supply circuit.

[0052] Specifically, when the circuit is powered on, the external power supply is input into the power supply circuit. The power supply circuit in this power supply circuit directly generates two low-voltage power supplies (the first low-voltage power supply and the second low-voltage power supply). At the same time, due to the first low-voltage power supply generated by the power supply circuit, a voltage drop is generated across the two ends of the first resistor R1. Thus, a third controllable current and a fourth controllable current flow through the third controllable current source G3 and the fourth controllable current source G4 respectively. Therefore, the source voltages of the fifth switching transistor M5 and the sixth switching transistor M6 are both pulled up to the voltage V1 of the first low-voltage power supply. At the same time, since the gate voltage of the fifth switching transistor M5 is equal to the voltage V2 of the second low-voltage power supply, the fifth switching transistor M5 is turned on. At this time, a current flows through the fifth resistor R5, and a voltage drop is generated across the two ends of the fifth resistor R5. Therefore, a sixth controllable current flows through the sixth controllable current source G6. And, the current coefficient of the sixth controllable current source G6 is designed to be 1. Thus, it can be obtained at this time that the current flowing through the fifth switching transistor M5 = the current flowing through the fifth resistor R5 = the sixth controllable current.

[0053] Meanwhile, when the circuit is just powered on, the eighth controllable current source G8 is not conducting, so the gate of the sixth switching transistor M6 is grounded through the eleventh resistor R11. Therefore, the gate-source voltage difference of the fifth switching transistor M5 is less than that of the sixth switching transistor M6, and the current flowing through the sixth switching transistor M6 is greater than that flowing through the fifth switching transistor M5. Since the sum of the current flowing through the sixth switching transistor M6 and the current flowing through the fifth switching transistor M5 is equal to the third controllable current, it can be obtained that the current flowing through the fifth switching transistor M5 is less than half of the third controllable current. And the fourth controllable current is equal to half of the third controllable current, and the current flowing through the fifth switching transistor M5 is equal to the sixth controllable current. Therefore, the sixth controllable current is less than the fourth controllable current, the voltage at point B is pulled up, and the seventh switching transistor M7 conducts. At this time, a current flows through the eighth resistor R8, generating a voltage drop across the eighth resistor R8. This voltage drop causes an eighth controllable current to be generated in the eighth controllable current source G8. At this time, the eighth controllable current flows through the ninth resistor R9 and the eleventh resistor R11. Therefore, the gate voltage of the sixth switching transistor gradually increases.

[0054] When the gate voltage of the sixth switching transistor gradually rises to be greater than the voltage V2 of the second low-voltage power supply, the gate-source voltage difference of the fifth switching transistor M5 is greater than that of the sixth switching transistor M6, and the current flowing through the sixth switching transistor M6 is less than that flowing through the fifth switching transistor M5. Since the sum of the current flowing through the sixth switching transistor M6 and the current flowing through the fifth switching transistor M5 is equal to the third controllable current, it can be obtained that the current flowing through the fifth switching transistor M5 is greater than half of the third controllable current. And the fourth controllable current is equal to half of the third controllable current, and the current flowing through the fifth switching transistor M5 is equal to the sixth controllable current. Therefore, the sixth controllable current is greater than the fourth controllable current, the voltage at point B is pulled down, the seventh switching transistor M7 is turned off, no current flows through the eighth resistor R8, and the gate voltage of the sixth switching transistor gradually decreases. The circuit enters the next cycle. Therefore, when the power supply circuit enters the stable state, the gate voltage of the sixth switching transistor is equal to the voltage V2 of the second low-voltage power supply. So at this time, it can be obtained that the voltage of the second low-voltage power supply , the output voltage . That is, when the power supply circuit enters the stable state, the power supply circuit is in the normal output mode, and at the same time the output circuit is in the second working state.

[0055] In an alternative embodiment, as Figure 2 shown, the current limiting circuit 30 includes: a first controllable current source G1, a second controllable current source G2, a fifth controllable current source G5, a seventh controllable current source G7, a first switching transistor M1, a second switching transistor M2, a third switching transistor M3, a fourth switching transistor M4, a second resistor R2, a fourth resistor R4, and a tenth resistor R10. The ratio of the first controllable current generated by the first controllable current source G1 to the second controllable current generated by the second controllable current source G2 is two to one.

[0056] The positive control terminal and the input terminal of the first controllable current source G1 are connected to the positive control terminal and the input terminal of the second controllable current source G2, the first terminal of the third switching transistor M3, the third terminal of the power supply circuit 10, the first terminal of the first current source circuit 20, and the first terminal of the output circuit 40. The negative control terminal of the first controllable current source G1 is connected to the negative control terminal of the second controllable current source G2, the second terminal of the first current source circuit 20, and the third terminal of the output circuit 40. The output terminal of the first controllable current source G1 is connected to the first terminal of the first switching transistor M1 and the first terminal of the second switching transistor M2. The second terminal of the first switching transistor M1 is connected to the fourth terminal of the power supply circuit and the second terminal of the output circuit. The third terminal of the first switching transistor M1 is connected to one end of the second resistor R2 and the positive control terminal of the fifth controllable current source G5. The second terminal of the second switching transistor M2 is connected to the output terminal of the seventh controllable current source G7 and one end of the tenth resistor R10. The third terminal of the second switching transistor M2 and the other end of the second resistor R2 are grounded.

[0057] The output terminal of the second controllable current source G2 is connected to the second terminal of the third switching transistor M3 and the input terminal of the fifth controllable current source G5. The third terminal of the third switching transistor M3 is connected to the first terminal of the fourth switching transistor M4 and one end of the fourth resistor R4. The negative control terminal and the output terminal of the fifth controllable current source G5, the other end of the fourth resistor R4, the other end of the tenth resistor R10, and the second terminal of the fourth switching transistor M4 are grounded. The third terminal of the fourth switching transistor M4 is connected to the fourth terminal of the output circuit. The positive control terminal and the input terminal of the seventh controllable current source G7 are connected to an external power supply. The negative control terminal of the seventh controllable current source G7 is connected to the fifth terminal of the output circuit.

[0058] Specifically, the first low-voltage power supply generated by the power supply circuit causes a voltage drop across the first resistor R1. Thus, a first controllable current and a second controllable current flow through the first controllable current source G1 and the second controllable current source G2, respectively. Therefore, the source voltages of the first switching transistor M1 and the second switching transistor M2 are both pulled up to the voltage V1 of the first low-voltage power supply. At the same time, since the gate voltage of the first switching transistor M1 is equal to the voltage V2 of the second low-voltage power supply, the first switching transistor M1 is turned on. At this time, a current flows through the second resistor R2, causing a voltage drop across the second resistor R2. Therefore, a fifth controllable current flows through the fifth controllable current source G5. And, by designing the current coefficient of the fifth controllable current source G5 to be 1, it can be obtained at this time that the current flowing through the first switching transistor M1 = the current flowing through the second resistor R2 = the fifth controllable current.

[0059] ​When the circuit is just powered on, since the seventh controllable current source G7 is not conducting, the gate of the second switching transistor M2 is grounded through the tenth resistor R10. Therefore, the gate-source voltage difference of the first switching transistor M1 is less than that of the second switching transistor M2, and the current flowing through the second switching transistor M2 is greater than that flowing through the first switching transistor M1. Since the sum of the current flowing through the first switching transistor M1 and the current flowing through the second switching transistor M2 is equal to the first controllable current, it can be obtained that the current flowing through the first switching transistor M1 is less than half of the first controllable current, and the second controllable current is equal to half of the first controllable current. The current flowing through the first switching transistor M1 is equal to the fifth controllable current. Therefore, the fifth controllable current is less than the second controllable current, the voltage at point A is pulled up, the third switching transistor M3 conducts, and after conduction, the third switching transistor M3 pulls up the gate voltage of the fourth switching transistor M4, and the fourth switching transistor M4 turns off. At the same time, when a current flows through the eighth resistor R8 in the output circuit, a voltage drop is generated across the eighth resistor R8, and this voltage drop causes a seventh controllable current to be generated in the seventh controllable current source G7 (the ratio of the seventh controllable current to the eighth controllable current is 1:N). Therefore, the gate voltage of the second switching transistor M2 gradually increases.

[0060] Moreover, when the power supply circuit is in the normal output mode, almost all of the eighth controllable current flows through the output terminal to the power supply load, and only a very small proportion of the eighth controllable current flows to the ninth resistor R9 and the eleventh resistor R11. Therefore, by detecting the seventh controllable current that has a proportional relationship with the eighth controllable current, the current flowing to the power supply load can be detected. Thus, at this time, by selecting appropriate proportional coefficient N and the resistance value of the tenth resistor R10, the designed value of the seventh controllable current is calculated such that when the eighth controllable current (i.e., the load current) is greater than the threshold current, the seventh controllable current is greater than the designed value, and the power supply circuit enters the current limiting mode.

[0061] Specifically, when the eighth controllable current (i.e., the load current) is greater than the threshold current, the seventh controllable current is greater than the designed value. Therefore, at this time, the gate voltage of the second switching transistor is greater than the voltage V2 of the second low-voltage power supply. The gate-source voltage difference of the first switching transistor M1 is greater than the gate-source voltage difference of the second switching transistor M2. The current flowing through the second switching transistor M2 is less than the current flowing through the first switching transistor M1. Since the sum of the current flowing through the first switching transistor M1 and the current flowing through the second switching transistor M2 is equal to the first controllable current, it can be obtained that the current flowing through the first switching transistor M1 is greater than half of the first controllable current. The second controllable current is equal to half of the first controllable current. The current flowing through the first switching transistor M1 is equal to the fifth controllable current. Therefore, the fifth controllable current is greater than the second controllable current, and the voltage at point A is pulled down. The third switching transistor M3 is turned off, and the gate voltage of the fourth switching transistor M4 is pulled down by the fourth resistor R4 (i.e., the current-limiting circuit enters the third state from the first state). At the same time, when the current-limiting circuit enters the third state from the first state, a current must flow through the seventh switching transistor M7. Therefore, the voltage at point B is at a high level. That is, at this time, the source voltage of the fourth switching transistor M4 is also at a high level. Therefore, at this time, the fourth switching transistor M4 is turned on, and the voltage at point B is pulled down through the fourth switching transistor M4, and the seventh switching transistor M7 is turned off, realizing the current-limiting function (i.e., the output circuit enters the fourth state from the second state).

[0062] After that, when the circuit fault disappears and the eighth controllable current (i.e., the load current) is less than the threshold current, the seventh controllable current is less than the designed value. Therefore, at this time, the gate voltage of the second switching transistor is less than the voltage V2 of the second low-voltage power supply. Therefore, the gate-source voltage difference of the first switching transistor M1 is less than the gate-source voltage difference of the second switching transistor M2. The current flowing through the second switching transistor M2 is greater than the current flowing through the first switching transistor M1. Since the sum of the current flowing through the first switching transistor M1 and the current flowing through the second switching transistor M2 is equal to the first controllable current, it can be obtained that the current flowing through the first switching transistor M1 is less than half of the first controllable current. The second controllable current is equal to half of the first controllable current. The current flowing through the first switching transistor M1 is equal to the fifth controllable current. Therefore, the fifth controllable current is less than the second controllable current, and the voltage at point A is pulled up. The third switching transistor M3 is turned on, and the turned-on third switching transistor M3 pulls up the gate voltage of the fourth switching transistor M4, and the fourth switching transistor M4 is turned off (i.e., the current-limiting circuit returns to the first state from the second state), and the circuit enters the normal output mode. At the same time, the output circuit returns to the first state from the fourth state.

[0063] In an alternative embodiment, as Figure 2As shown, the current limiting circuit 30 further includes a third resistor R3. One end of the third resistor R3 is connected to the third terminal of the second switching transistor M2, and the other end of the third resistor R3 is grounded. The resistance value of the third resistor R3 is equal to the resistance value of the second resistor R2. The output circuit 40 further includes a sixth resistor R6. One end of the sixth resistor R6 is connected to the third terminal of the sixth switching transistor M6, and the other end of the sixth resistor R6 is grounded. The resistance value of the sixth resistor R6 is the same as the resistance value of the fifth resistor R5.

[0064] Specifically, when the power supply circuit is in a stable operating state in the normal output mode, the current flowing through the fifth switching transistor M5 is equal to the current flowing through the sixth switching transistor M6. Therefore, at this time, a sixth resistor R6 is provided in the branch of the sixth switching transistor M6, and the resistance value of the sixth resistor R6 is designed to be equal to the resistance value of the fifth resistor R5. Thus, when the current flowing through the fifth switching transistor M5 is equal to the current flowing through the sixth switching transistor M6, the voltage drops across the fifth resistor R5 and the sixth resistor R6 are the same. As a result, when the circuit is in a stable operating state in the normal output mode, the voltages at the drains of the fifth switching transistor M5 and the sixth switching transistor M6 are exactly equal. Therefore, it can be obtained that when the current flowing through the fifth switching transistor M5 is equal to the current flowing through the sixth switching transistor M6 and the voltages at the drains of the fifth switching transistor M5 and the sixth switching transistor M6 are also exactly equal, the gate voltages of the fifth switching transistor M5 and the sixth switching transistor M6 must be exactly equal. This ensures that when the circuit is in a stable operating state in the normal output mode, the current and voltage of each path in the output circuit are exactly matched, and the gate voltage of the sixth switching transistor M6 is precisely equal to the voltage V2 of the second low-voltage power supply. Therefore, through the above structure, the accuracy of the output voltage VOUT can be improved.

[0065] Meanwhile, as can be seen from the above analysis, when the circuit is at the current-limiting switching node where it switches from the normal operating mode to the current-limiting mode, the current flowing through the second switching transistor M2 is equal to the current flowing through the first switching transistor M1. Therefore, at this time, a third resistor R3 is provided in the branch of the second switching transistor M2, and the resistance value of the third resistor R3 is designed to be equal to the resistance value of the second resistor R2. Thus, when the current flowing through the first switching transistor M1 is equal to the current flowing through the second switching transistor M2, the voltage drops across the second resistor R2 and the third resistor R3 are the same, so that when the circuit is at the current-limiting switching node where it switches from the normal operating mode to the current-limiting mode, the voltages at the drains of the first switching transistor M1 and the second switching transistor M2 are exactly equal. Therefore, it can be obtained at this time that when the current flowing through the first switching transistor M1 is equal to the current flowing through the second switching transistor M2 and the voltages at the drains of the first switching transistor M1 and the second switching transistor M2 are also exactly equal, the gate voltages of the first switching transistor M1 and the second switching transistor M2 must be exactly equal, thereby ensuring that when the circuit is at the current-limiting switching node where it switches from the normal operating mode to the current-limiting mode, the gate voltage of the second switching transistor M2 is exactly equal to the voltage V2 of the second low-voltage power supply. Therefore, through the above structure, the accuracy of the current-limiting switching node can be improved, thereby further improving the safety and reliability of the circuit.

[0066] According to the above circuit, since the eighth resistor R8, the seventh controllable current source G7, and the eighth controllable current source G8 are all connected to an external high-voltage power supply, all the devices connected below the eighth resistor R8 and the seventh controllable current source G7 need to use high-voltage devices, that is, the seventh switching transistor M7 must use a high-voltage switching transistor. However, the high-voltage switching transistor has a large leakage current, which may cause the seventh switching transistor M7 to not conduct or turn off correctly when the circuit is at the current-limiting switching node where it switches from the normal operating mode to the current-limiting mode. At the same time, the disturbance of the external high-voltage power supply may be conducted to one end of the tenth resistor R10, thereby causing the current-limiting switching node to drift, reducing the accuracy of the current-limiting switching node and the safety and reliability of the circuit.

[0067] Thus, as Figure 3As shown, the power supply circuit further includes: an isolation circuit. The first end of the isolation circuit is connected to one end of the eighth resistor R8, the negative control end of the seventh controllable current source G7, and the negative control end of the eighth controllable current source G8. The second end of the isolation circuit is connected to the third end of the power supply circuit 10, the first end of the first current source circuit 20, the first end of the current limiting circuit 30, and the first end of the output circuit 40. The third end of the isolation circuit is connected to the second end of the seventh switching tube M7. The fourth end of the isolation circuit is connected to the output end of the seventh controllable current source G7. The fifth end of the isolation circuit is connected to the second end of the second switching tube M2 and one end of the tenth resistor R10. The sixth end of the isolation circuit is grounded. The seventh end of the isolation circuit is connected to the output end of the eighth controllable current source G8, the other end of the ninth resistor R9, and the output end of the power supply circuit.

[0068] Specifically, as Figure 3 shown, the isolation circuit includes an eighth switching tube M8, a ninth controllable current source G9, a twelfth resistor R12, and a thirteenth resistor R13. The first end of the eighth switching tube M8 is connected to one end of the eighth resistor R8, the negative control end of the seventh controllable current source G7, and the negative control end of the eighth controllable current source G8. The second end of the eighth switching tube M8 is connected to the third end of the power supply circuit 10, the first end of the first current source circuit 20, the first end of the current limiting circuit 30, and the first end of the output circuit 40. The third end of the eighth switching tube M8 is connected to the second end of the seventh switching tube M7. The input end of the ninth controllable current source G9 is connected to the output end of the seventh controllable current source G7. The output end of the ninth controllable current source G9 is connected to the second end of the second switching tube M2 and one end of the tenth resistor R10. The negative control end of the ninth controllable current source G9 is connected to one end of the thirteenth resistor R13 and one end of the twelfth resistor R12. The other end of the thirteenth resistor R13 is grounded. The positive control end of the ninth controllable current source G9 is connected to the other end of the twelfth resistor R12, the output end of the eighth controllable current source G8, the other end of the ninth resistor R9, and the output end of the power supply circuit.

[0069] Among them, the eighth switching transistor M8 plays a role in isolating high voltage, enabling the device (the seventh switching transistor M7) below the eighth switching transistor M8 to adopt low-voltage devices, thereby ensuring that the leakage current of the seventh switching transistor M7 is small and improving the safety and reliability of the circuit. At the same time, a ninth controllable current source G9 with a relatively large current coefficient is set in the circuit, such that the ninth controllable current generated by the ninth controllable current source G9 according to the twelfth resistor R12 is greater than the seventh controllable current, that is, the current capacity of the ninth controllable current source G9 is greater than that of the seventh controllable current source G7. Therefore, when the power supply circuit is working, the current flowing through the branch of the seventh controllable current source G7, the ninth controllable current source G9, and the tenth resistor R10 is equal to the seventh controllable current, thereby ensuring that the isolation circuit will not affect the operation of the power supply circuit. Moreover, due to the setting of this isolation circuit, the disturbance of the external high-voltage power supply will not be conducted to one end of the tenth resistor R10, thereby ensuring that the current-limiting switching node will not drift and improving the safety and reliability of the circuit.

[0070] It should be noted that MOS transistors can be used for the switching transistors in the output circuit, the current-limiting circuit, and the isolation circuit.

[0071] An embodiment of the present invention provides a power supply circuit, as Figure 4 shown. The power supply circuit includes a second current source circuit 50, a starting circuit 60, an adjusting circuit 70, and a voltage output circuit 80. The second current source circuit 50 is used to conduct and work after an external power supply is connected. The starting circuit 60 is used to provide a starting voltage for the adjusting circuit 70 according to the external power supply and the second current source circuit 50 that is conducting. The adjusting circuit 70 is used to adjust the current of the voltage output circuit 80 and make it stable. The voltage output circuit 80 is used to output a first low-voltage power supply and a second low-voltage power supply after the current is stable.

[0072] Among them, the first end of the second current source circuit 50 is connected to the external power supply, the first end of the starting circuit 60, the first end of the adjusting circuit 70, and the first end of the voltage output circuit 80. The second end of the second current source circuit 50 is connected to the second end of the starting circuit 60 and the second end of the adjusting circuit 70. The third end of the second current source circuit 50 is grounded. The third end of the starting circuit 60 is connected to the third end of the adjusting circuit 70 and the second end of the voltage output circuit 80. The fourth end of the starting circuit 60 is grounded. The fifth end of the starting circuit 60 is connected to the seventh end of the adjusting circuit 70. The fourth end of the adjusting circuit 70 is connected to the third end of the voltage output circuit 80. The fifth end of the adjusting circuit 70 is connected to the fourth end of the voltage output circuit 80. The sixth end of the adjusting circuit 70 is grounded. The fifth end of the voltage output circuit 80 outputs the first low-voltage power supply. The second end of the voltage output circuit 80 outputs the second low-voltage power supply. The sixth end of the voltage output circuit 80 is grounded.

[0073] Specifically, the second current source circuit 50 includes a second current source I2 and a twenty-second resistor R22; the starting circuit 60 includes an eleventh controllable current source G11, a fifteenth controllable current source G15, a fourteenth resistor R14, a fourteenth MOS transistor M14, a fifteenth MOS transistor M15, and a second diode D2; the adjustment circuit 70 includes a tenth controllable current source G10, a twelfth controllable current source G12, a thirteenth controllable current source G13, a fourteenth controllable current source G14, a first triode Q1, a second triode Q2, a ninth MOS transistor M9, a tenth MOS transistor M10, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, and a first diode D1; the voltage output circuit 80 includes a thirteenth MOS transistor M13, a third triode Q3, a nineteenth resistor R19, a twentieth resistor R20, a twenty-first resistor R21, and a fourth triode Q4. The connection manner between each device is as Figure 5 shown.

[0074] The working principle of this power supply circuit is as follows:

[0075] When the circuit is powered on, the external high-voltage power supply of the chip inputs into the power supply circuit. The second current source I2 generates a second current and flows into the twenty-second resistor R22. At this time, a tenth controllable current and an eleventh controllable current flow through the tenth controllable current source G10 and the eleventh controllable current source G11 respectively; the eleventh controllable current flows into the fourteenth resistor R14. At this time, a twelfth controllable current, a thirteenth controllable current, a fourteenth controllable current, and a fifteenth controllable current flow through the twelfth controllable current source G12, the thirteenth controllable current source G13, the fourteenth controllable current source G14, and the fifteenth controllable current source G15 respectively (wherein, the ratio of the thirteenth controllable current to the fourteenth controllable current is 1:1). At this time, the gate voltages of the fourteenth MOS transistor M14 and the fifteenth MOS transistor M15 are pulled up by the fifteenth controllable current source G15. At the same time, the source of the fourteenth MOS transistor M14 is grounded through the second diode D2. Also, since the voltage VIN of the external high-voltage power supply is greater than the sum of the gate-source voltage difference VGS of the fourteenth MOS transistor M14 and the forward conduction voltage drop VD2 of the second diode D2, therefore, at this time, both the fourteenth MOS transistor M14 and the second diode D2 are turned on. At this time, by Figure 3As can be seen from the structural schematic diagram shown, the gate voltages of the fourteenth MOS transistor M14 and the fifteenth MOS transistor M15 are both equal to VGS + VD2. Therefore, it can be obtained that when the source voltage of the fifteenth MOS transistor M15 is less than VD2, the fifteenth MOS transistor M15 conducts. At this time, the source voltage of the fifteenth MOS transistor M15 can be clamped at VD2. When the source voltage of the fifteenth MOS transistor M15 is greater than VD2, although the fifteenth MOS transistor M15 does not conduct, at this time, the base voltage of the first triode Q1 is greater than VD2. Therefore, in this application, the base voltage of the first triode Q1 is at least VD2, and the base voltage of the second triode Q2 is at least close to VD2. Also, since the emitters of the first triode Q1 and the second triode Q2 are grounded through the tenth controllable current source G10, at this time, when the base voltage of the first triode Q1 is at least VD2 and the base voltage of the second triode Q2 is at least close to VD2, the first triode Q1 and the second triode Q2 can conduct smoothly; at the same time, in order to further ensure the smooth conduction of the first triode Q1 and the second triode Q2, M diodes can be connected in series in the branch of the second diode D2, so as to ensure that the base voltage of the first triode Q1 is approximately M VD2, and the base voltage of the second triode Q2 is close to M VD2.

[0076] After the first triode Q1 and the second triode Q2 are turned on, the cathode of the first diode D1 is pulled low, and the first diode D1 conducts. Therefore, current flows through both the first triode Q1 and the second triode Q2. At this time, since the ratio of the number of the first triodes Q1 to the number of the second triodes Q2 is 1:K, and when the circuit is just powered on, the base voltage of the first triode Q1 and the base voltage of the second triode Q2 differ very little. Therefore, at this time, the ratio of the number of triodes has a greater impact on the current flowing through the triodes. Thus, the current IC1 flowing through the first triode Q1 is less than the current IC2 flowing through the second triode Q2. Also, since the resistance values of the fifteenth resistor R15 and the sixteenth resistor R16 are equal, the voltage drop across the fifteenth resistor R15 is less than the voltage drop across the sixteenth resistor R16. Therefore, it can be obtained that the gate voltage of the ninth MOS transistor M9 connected to the fifteenth resistor R15 is greater than the gate voltage of the tenth MOS transistor M10 connected to the sixteenth resistor R16. Also, since the source voltages of the ninth MOS transistor M9 and the tenth MOS transistor M10 are equal, the source-gate voltage difference of the ninth MOS transistor M9 is less than the source-gate voltage difference of the tenth MOS transistor M10, making the current flowing through the tenth MOS transistor M10 greater than the current flowing through the ninth MOS transistor M9. At this time, since the resistance values of the seventeenth resistor R17 and the eighteenth resistor R18 are equal, it can be obtained that the voltage drop across the eighteenth resistor R18 is greater than the voltage drop across the seventeenth resistor R17. Therefore, the source voltage of the eleventh MOS transistor M11 is less than the source voltage of the twelfth MOS transistor M12, and it can be obtained that the gate-source voltage difference of the twelfth MOS transistor M12 is less than the gate-source voltage difference of the eleventh MOS transistor M11. Thus, it can be obtained that the current flowing through the eleventh MOS transistor M11 is greater than the current flowing through the twelfth MOS transistor M12. Since the thirteenth controllable current and the fourteenth controllable current are equal, it can be obtained at this time that the current flowing into point C = the fourteenth controllable current = the current flowing through the eleventh MOS transistor M11, and the current flowing out of point C = the current flowing through the twelfth MOS transistor M12. Therefore, the current flowing into point C is greater than the current flowing out of point C, and the voltage of point C is pulled high, that is, the gate voltage of the thirteenth MOS transistor M13 is pulled high to the voltage VIN. At the same time, the source of the thirteenth MOS transistor M13 is grounded through the third triode Q3, the nineteenth resistor R19, the twentieth resistor R20, the twenty-first resistor R21, and the fourth triode Q4. And the voltage VIN is obviously much greater than the voltage difference VBE between the base and the emitter of the third triode Q3 + the voltage difference VBE between the base and the emitter of the fourth triode Q4 + the gate-source voltage difference VGS of the thirteenth MOS transistor M13. Therefore, the thirteenth MOS transistor M13 conducts. At this time, an internal current IM is generated in the branch composed of the thirteenth MOS transistor M13, the third triode Q3, the nineteenth resistor R19, the twentieth resistor R20, the twenty-first resistor R21, and the fourth triode Q4. As the internal current IM increases,The base voltages of the first triode Q1 and the second triode Q2 both gradually increase. Since the voltage drop across the twentieth resistor R20 becomes larger and larger, the base voltage of the first triode Q1 is larger than that of the second triode Q2. Therefore, the voltage difference VBE1 between the base and emitter of the first triode Q1 is larger than the voltage difference VBE2 between the base and emitter of the second triode Q2. Moreover, the influence of the voltage difference between the base and emitter of the triode on the current is greater than the influence of the number of parallel-connected triodes on the current. Thus, at this time, it can be obtained that as the internal current IM increases, the current IC1 flowing through the first triode Q1 gradually becomes larger than the current IC2 flowing through the second triode Q2. At this time, combining the above analysis, it can be known that the current flowing into C is less than the current flowing out from point C, and the voltage at point C is pulled down, that is, the gate voltage of the thirteenth MOS transistor M13 is pulled down. At this time, by designing the parameters of the eighteenth resistor R18 and the current flowing through the twelfth MOS transistor M12, the terminal voltage of the eighteenth resistor R18 at this time is lower than the voltage difference VBE between the base and emitter of the third triode Q3 + the voltage difference VBE between the base and emitter of the fourth triode Q4 + the gate-source voltage difference VGS of the thirteenth MOS transistor M13. Therefore, when the voltage at point C is pulled down, the thirteenth MOS transistor M13 is turned off, the internal current IM decreases, and the base voltages of the first triode Q1 and the second triode Q2 both decrease. After that, when the current IC1 flowing through the first triode Q1 is less than the current IC2 flowing through the second triode Q2 again, the circuit enters the next cycle.

[0077] As can be seen from the above description, when the power supply circuit enters the stable working state, the current IC1 flowing through the first triode Q1 is equal to the current IC2 flowing through the second triode Q2. At the same time, from the structural schematic diagram of the power supply circuit, that is Figure 4 it can be known that VBE1 = VBE2 + VR20, where VR20 is the voltage difference across the twentieth resistor R20, and at this time, combining with the triode current formula, it can be obtained that: from this, it can be known that the internal current IM where Vt is the thermal voltage and R20 is the resistance value of the twentieth resistor.

[0078] Therefore, it can be obtained that the voltage of the first low-voltage power supply of the power supply circuit is expressed by the following formula:

[0079] ;

[0080] The voltage of the second low-voltage power supply output is expressed by the following formula:

[0081] ;

[0082] At this time, first, the third triode Q3 and the fourth triode Q4 are designed as triodes with exactly the same parameters. Therefore, it can be obtained that the VBE3 of the third triode Q3 = the VBE4 of the fourth triode Q4, denoted as VBE. Therefore, , , second, the VBE of the triode is a negative temperature parameter, and the thermal voltage Vt of the triode is a positive temperature parameter. Therefore, by appropriately matching the parameters of K, R19, R20, and R21, the voltage V1 of the first low-voltage power supply and the voltage V2 of the second low-voltage power supply output can be made independent of temperature, so that the voltage generator not only outputs two voltages but also improves the accuracy of the output voltage.

[0083] In addition, when the power supply circuit is just powered on, the currents in the first triode Q1 and the second triode Q2 are small. Therefore, at this time, the voltage drops across the fifteenth resistor R15 and the sixteenth resistor R16 are small. At this time, if there is no first diode D1 and the fifteenth resistor R15 and the sixteenth resistor R16 are directly connected to the external high-voltage power supply, then the voltage at the end of the fifteenth resistor R15 and the sixteenth resistor R16 far from the external high-voltage power supply will be large, approaching the voltage VIN of the external high-voltage power supply, resulting in a large gate voltage of the ninth MOS transistor M9 and the tenth MOS transistor M10, making the ninth MOS transistor M9 and the tenth MOS transistor M10 unable to conduct; therefore, at this time, the first diode D1 is set in the power supply circuit, so that the voltage at the end of the fifteenth resistor R15 and the sixteenth resistor R16 close to the external high-voltage power supply is VIN - VD1, where VD1 is the forward conduction voltage drop of the first diode D1; and from the appendix Figure 4 it can be seen that the twelfth controllable current source G12 pulls up the source voltage of the ninth MOS transistor M9 and the tenth MOS transistor M10 to the voltage VIN of the external high-voltage power supply. Therefore, when the gate voltage of the ninth MOS transistor M9 and the tenth MOS transistor M10 is less than VIN - VGS, they can conduct smoothly. And from the related technology, it is known that the forward conduction voltage drop of the diode is slightly less than the gate-source voltage difference VGS after the MOS transistor conducts. Therefore, when the first diode D1, the fifteenth resistor R15, and the sixteenth resistor R16 are set in the circuit, it can be basically ensured that the voltage at the end of the fifteenth resistor R15 and the sixteenth resistor R16 far from the external high-voltage power supply, that is, the gate voltage of the ninth MOS transistor M9 and the tenth MOS transistor M10, is less than VIN - VGS, so that the ninth MOS transistor M9 and the tenth MOS transistor M10 conduct smoothly.

[0084] At the same time, in order to further ensure the smooth conduction of the ninth MOS transistor M9 and the tenth MOS transistor M10, N diodes can be connected in series in the branch of the first diode D1, so as to further ensure that the gate voltage of the ninth MOS transistor M9 and the tenth MOS transistor M10 is less than VIN - VGS.

[0085] After the power supply circuit enters the stable working state, set the voltage V2 of the second low-voltage power supply output by the power supply circuit to be greater than VGS, so as to ensure that the fifteenth MOS transistor M15 is in the off state and will not affect the magnitudes of the two voltages output by the power supply circuit.

[0086] The first low-voltage power supply output terminal of the power supply circuit is connected to an external high-voltage power supply through the thirteenth MOS transistor M13. Therefore, the currents output by the first low-voltage power supply output terminal to the current limiting circuit and the output circuit both come from the external high-voltage power supply, and the currents it outputs to the current limiting circuit and the output circuit do not affect the magnitude of the internal current IM. Therefore, the first low-voltage power supply output terminal has current-carrying capacity; while the second low-voltage power supply output terminal is connected to the external high-voltage power supply through the nineteenth resistor R19, the third triode Q3, and the thirteenth MOS transistor M13. Due to the adjustment of the circuit by the twentieth resistor R20, the twenty-first resistor R21, and the fourth triode Q4, the currents flowing through the above three devices remain unchanged. Therefore, at this time, if the second low-voltage power supply output terminal outputs current to the current limiting circuit and the output circuit, it will inevitably increase the internal current IM, thereby making the voltage V1 of the first low-voltage power supply too large. Therefore, the second low-voltage power supply output terminal does not have current-carrying capacity.

[0087] In this embodiment, only one power supply circuit is provided in the power supply circuit, and two low-voltage power supplies that are not affected by temperature and have high precision can be generated, thereby improving the output voltage precision and current limiting precision of the power supply circuit and reducing the volume of the power supply circuit; at the same time, the power supply circuit can provide a first low-voltage power supply with current-carrying capacity and a second low-voltage power supply without current-carrying capacity. After being reasonably matched with the current limiting circuit and the output circuit, etc., the above-mentioned power supply circuit with current limiting function can be obtained.

[0088] Although the exemplary embodiments and their advantages have been described in detail, those skilled in the art can make various changes, substitutions, and modifications to these embodiments without departing from the spirit of the present invention and the protection scope defined by the appended claims. Such modifications and variations all fall within the scope defined by the appended claims. For other examples, those of ordinary skill in the art should easily understand that the order of the process steps can be changed while maintaining the protection scope of the present invention.

[0089] In addition, the scope of application of the present invention is not limited to the processes, mechanisms, manufacturing, compositions of matter, means, methods, and steps of the specific embodiments described in the specification. From the disclosure of the present invention, as those of ordinary skill in the art will readily understand, for processes, mechanisms, manufacturing, compositions of matter, means, methods, or steps that currently exist or will be developed in the future, and which perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described in the present invention, they can be applied in accordance with the present invention. Therefore, the appended claims of the present invention are intended to include such processes, mechanisms, manufacturing, compositions of matter, means, methods, or steps within their scope of protection.

Claims

1. A power supply circuit with current limiting function, characterized in that: include: A power supply circuit, used to simultaneously generate a first low-voltage power supply and a second low-voltage power supply after an external power supply is connected; A first current source circuit, configured to operate according to a first low-voltage power supply; A current limiting circuit is used to conduct according to an external power supply, two low-voltage power supplies and a first current source circuit that is conducting and is in a first working state; The output circuit is used to stabilize the voltage at the output end of the power supply circuit at a first preset value according to the external power supply, the two low-voltage power supplies and the first current source circuit that is turned on and is in a second working state; When the output current of the output circuit is greater than the second preset value, the current limiting circuit switches from the first working state to the third working state according to the second low-voltage power supply and the current in the output circuit that is greater than the second preset value, and switches the output circuit from the second working state to the fourth working state, and the output current of the output circuit decreases; when the output current of the output circuit is less than the second preset value, the current limiting circuit returns to the first working state according to the second low-voltage power supply and the current in the output circuit that is less than the second preset value, and returns the output circuit to the second working state, stabilizing the voltage at the output end of the power supply circuit at the first preset value; The power supply circuit includes a second current source circuit, a starting circuit, a regulating circuit and a voltage output circuit; The second current source circuit is used to turn on and work after the external power supply is connected, the starting circuit is used to provide a starting voltage for the regulation circuit according to the external power supply and the second current source circuit that is turned on, the regulation circuit is used to adjust the current of the voltage output circuit and stabilize it, and the voltage output circuit is used to output the first low-voltage power supply and the second low-voltage power supply after the current is stable.

2. The power supply circuit with current limiting function according to claim 1, characterized in that: The power supply circuit has a first end connected to an external power supply, a second end connected to ground, a third end connected to a first end of the first current source circuit, a first end of the current limiting circuit and a first end of the output circuit, and a fourth end of the power supply circuit connected to a second end of the current limiting circuit and a second end of the output circuit; The first current source circuit has a second end connected to the third end of the current limiting circuit and the third end of the output circuit, and a third end connected to ground; The current limiting circuit has a fourth end connected to the external power supply, a fifth end connected to the fourth end of the output circuit, a sixth end connected to the fifth end of the output circuit, and a seventh end connected to ground; The output circuit has a sixth end connected to an external power source, a seventh end connected to an output end of a power supply circuit, and an eighth end connected to ground.

3. The power supply circuit with current limiting function according to claim 1, characterized in that: The first current source circuit includes: a first current source and a first resistor, one end of the first current source is connected to one end of the first resistor, the third end of the current limiting circuit and the third end of the output circuit, the other end of the first current source is grounded, and the other end of the first resistor is connected to the third end of the power supply circuit, the first end of the current limiting circuit and the first end of the output circuit.

4. The power supply circuit with current limiting function according to claim 1, characterized in that: The current limiting circuit includes: a first controllable current source, a second controllable current source, a fifth controllable current source, a seventh controllable current source, a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a second resistor, a fourth resistor and a tenth resistor; The positive control terminal and the input terminal of the first controllable current source are connected to the positive control terminal and the input terminal of the second controllable current source, the first terminal of the third switch tube, the third terminal of the power circuit, the first terminal of the first current source circuit and the first terminal of the output circuit; the negative control terminal of the first controllable current source is connected to the negative control terminal of the second controllable current source, the second terminal of the first current source circuit and the third terminal of the output circuit; the output terminal of the first controllable current source is connected to the first terminal of the first switch tube and the first terminal of the second switch tube; the second terminal of the first switch tube is connected to the fourth terminal of the power circuit and the second terminal of the output circuit; the third terminal of the first switch tube is connected to one terminal of the second resistor and the positive control terminal of the fifth controllable current source; the second terminal of the second switch tube is connected to the output terminal of the seventh controllable current source and one terminal of the tenth resistor; the third terminal of the second switch tube and the other terminal of the second resistor are grounded; The output end of the second controllable current source is connected to the second end of the third switch tube and the input end of the fifth controllable current source, the third end of the third switch tube is connected to the first end of the fourth switch tube and one end of the fourth resistor, the negative control end and the output end of the fifth controllable current source, the other end of the fourth resistor, the other end of the tenth resistor and the second end of the fourth switch tube are grounded, the third end of the fourth switch tube is connected to the fourth end of the output circuit, the positive control end and the input end of the seventh controllable current source are connected to an external power supply, and the negative control end of the seventh controllable current source is connected to the fifth end of the output circuit.

5. The power supply circuit with current limiting function according to claim 4, characterized in that: The current limiting circuit also includes a third resistor, one end of the third resistor is connected to the third end of the second switch tube, the other end of the third resistor is grounded, and the resistance of the third resistor is equal to the resistance of the second resistor.

6. The power supply circuit with current limiting function according to claim 4, characterized in that: The output circuit includes a third controllable current source, a fourth controllable current source, a sixth controllable current source, an eighth controllable current source, a fifth switch tube, a sixth switch tube, a seventh switch tube, a fifth resistor, a seventh resistor, an eighth resistor, a ninth resistor and an eleventh resistor; The positive control terminal and the input terminal of the third controllable current source are connected to the positive control terminal and the input terminal of the fourth controllable current source, the third terminal of the power supply circuit, the first terminal of the first current source circuit and the first terminal of the current limiting circuit; the negative control terminal of the third controllable current source is connected to the negative control terminal of the fourth controllable current source, the second terminal of the first current source circuit and the third terminal of the current limiting circuit; the output terminal of the third controllable current source is connected to the first terminal of the fifth switch tube and the first terminal of the sixth switch tube; the second terminal of the fifth switch tube is connected to the fourth terminal of the power supply circuit and the second terminal of the current limiting circuit; the third terminal of the fifth switch tube is connected to one terminal of the fifth resistor and the positive control terminal of the sixth controllable current source; the second terminal of the sixth switch tube is connected to one terminal of the ninth resistor and one terminal of the eleventh resistor; the third terminal of the sixth switch tube and the other terminal of the fifth resistor are grounded; The output end of the fourth controllable current source is connected to the first end of the seventh switch tube, the input end of the sixth controllable current source and the fifth end of the current limiting circuit, the second end of the seventh switch tube is connected to one end of the eighth resistor, the negative control end of the eighth controllable current source and the sixth end of the current limiting circuit, the third end of the seventh switch tube is connected to one end of the seventh resistor, the negative control end and the output end of the sixth controllable current source, the other end of the seventh resistor and the other end of the eleventh resistor are grounded, the other end of the eighth resistor is connected to the positive control end and the input end of the eighth controllable current source and the external power supply, and the output end of the eighth controllable current source is connected to the other end of the ninth resistor and the output end of the power supply circuit.

7. The power supply circuit with current limiting function according to claim 6, characterized in that: The third end of the power supply circuit outputs a first low-voltage power supply, and the fourth end of the power supply circuit outputs a second low-voltage power supply. The voltage of the first low-voltage power supply is greater than the voltage of the second low-voltage power supply, and the difference between the voltage of the first low-voltage power supply and the voltage of the second low-voltage power supply is greater than the threshold voltage of the first switch tube and the fifth switch tube.

8. The power supply circuit with current limiting function according to claim 6, characterized in that: The output circuit further includes a sixth resistor, one end of the sixth resistor is connected to the third end of the sixth switch tube, the other end of the sixth resistor is grounded, and the resistance value of the sixth resistor is the same as the resistance value of the fifth resistor.

9. The power supply circuit with current limiting function according to claim 6, characterized in that: The ratio of the first controllable current generated by the first controllable current source to the second controllable current generated by the second controllable current source is two to one, and the ratio of the third controllable current generated by the third controllable current source to the fourth controllable current generated by the fourth controllable current source is two to one.

10. The power supply circuit with current limiting function according to claim 6, characterized in that: The power supply circuit also includes: an isolation circuit, a first end of the isolation circuit connected to one end of the eighth resistor, the negative control end of the seventh controllable current source and the negative control end of the eighth controllable current source, a second end of the isolation circuit connected to the third end of the power supply circuit, the first end of the first current source circuit, the first end of the current limiting circuit and the first end of the output circuit, a third end of the isolation circuit connected to the second end of the seventh switch tube, a fourth end of the isolation circuit connected to the output end of the seventh controllable current source, a fifth end of the isolation circuit connected to the second end of the second switch tube and one end of the tenth resistor, a sixth end of the isolation circuit grounded, and a seventh end of the isolation circuit connected to the output end of the eighth controllable current source, the other end of the ninth resistor and the output end of the power supply circuit.

11. The power supply circuit with current limiting function according to claim 10, characterized in that: The isolation circuit includes an eighth switch tube, a ninth controllable current source, a twelfth resistor and a thirteenth resistor; The first end of the eighth switch tube is connected to one end of the eighth resistor, the negative control end of the seventh controllable current source and the negative control end of the eighth controllable current source. The second end of the eighth switch tube is connected to the third end of the power supply circuit, the first end of the first current source circuit, the first end of the current limiting circuit and the first end of the output circuit. The third end of the eighth switch tube is connected to the second end of the seventh switch tube. The input end of the ninth controllable current source is connected to the output end of the seventh controllable current source. The output end of the ninth controllable current source is connected to the second end of the second switch tube and one end of the tenth resistor. The negative control end of the ninth controllable current source is connected to one end of the thirteenth resistor and one end of the twelfth resistor. The other end of the thirteenth resistor is grounded. The positive control end of the ninth controllable current source is connected to the other end of the twelfth resistor, the output end of the eighth controllable current source, the other end of the ninth resistor and the output end of the power supply circuit.

12. The power supply circuit with current limiting function according to claim 11, characterized in that: The current capability of the ninth controllable current source is greater than the current capability of the seventh controllable current source.

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