A temperature-adaptive current-limiting circuit for power transistors

Abstract

The present application relates to a temperature adaptive current limiting circuit for a power transistor, comprising: an adaptive module, which generates a variable current for regulating the current limiting current based on the temperature of the power transistor; a current limiting module, which proportionally mirrors the output current of the power transistor to generate a mirror current and receives the variable current output by the adaptive module; when the temperature of the power transistor changes, the voltage provided to the control electrode of the power transistor is controlled based on the mirror current and the variable current; the output current of the transistor is limited to, when the temperature of the power transistor is less than a threshold temperature, the limiting current of the power transistor is a first current limiting current of a fixed value and is determined by the current limiting module; when the temperature of the power transistor is greater than or equal to the threshold temperature, the limiting current of the power transistor is a second current limiting current value that changes linearly and the change slope is determined by the adaptive module. The present application also relates to an electronic device.

Description

Technical Field

[0001] The present application relates to the field of electrical control, and in particular to a temperature adaptive current limiting circuit for a power transistor. Background Art

[0002] As an important electronic device, power transistors are widely used in automotive electronics, aerospace, communications and other fields. With the development of these fields, the performance and reliability requirements of power chips are becoming increasingly higher.

[0003] In actual applications, power chips have various working scenarios and complex working environments. Excessive loads leading to circuit overcurrent, short circuit, surge, etc. will increase the output current of power transistors, causing the power transistors to be damaged due to excessive temperature and performance degradation. In order to ensure that power chips can work safely, protection strategies are designed for power transistors in power chips, and current limiting protection is a relatively important part.

[0004] In the prior art, a temperature detection circuit is set in the power chip to prevent the power transistor from heating up and being damaged during operation. When the output current of the power transistor increases, the temperature of the power transistor rises, and the temperature detection circuit detects the heating of the power transistor and controls the current limiting module to limit the current of the power transistor. In practical applications, this method is limited by the single fixed current limiting current value provided by the current limiting module. The current limiting module can only limit the output current of the power transistor to not exceed the fixed current limiting current value, and cannot effectively reduce the temperature of the power transistor, causing the power transistor to be in a continuous heating state or even damaged. Summary of the invention

[0005] In view of the technical problems existing in the prior art, the present application proposes a temperature adaptive current limiting circuit for a power transistor, comprising: an adaptive module, coupled between a first pole and a second pole of the power transistor, configured to generate a variable current for regulating a current limiting current based on the temperature of the power transistor; a current limiting module, coupled between the first pole and the second pole of the power transistor and coupled to the output end of the adaptive module, whose output end is coupled to the control pole of the power transistor, configured to proportionally mirror the output current of the power transistor to generate a mirror current and receive the variable current output by the adaptive module, and when the temperature of the power transistor changes, the voltage provided to the control pole of the power transistor is controlled based on the mirror current and the variable current; wherein the temperature adaptive current limiting circuit limits the output current of the transistor to, when the temperature of the power transistor is less than a threshold temperature, the limiting current of the power transistor is a first current limiting current of a fixed value and is determined by the current limiting module; when the temperature of the power transistor is greater than or equal to the threshold temperature, the limiting current of the power transistor is a second current limiting current value that changes linearly and the change slope is determined by the adaptive module.

[0006] In particular, the temperature adaptive current limiting circuit, wherein the current limiting module includes: a first transistor and a first resistor, the first electrode of the first transistor is coupled to the first electrode of the power transistor, the second electrode of the first transistor is coupled to the second electrode of the power transistor through the first resistor, and the control electrode is coupled to the control electrode of the power transistor; a first amplifier and a second resistor, the negative input terminal of the first amplifier is coupled to the node where the first resistor is coupled to the second electrode of the first transistor, the output terminal of the first amplifier is coupled to the control electrode of the power transistor, and the positive input terminal of the first amplifier is coupled to the second electrode of the power transistor through the second resistor; a first current source and a voltage pump, which are coupled in series with each other between the positive input terminal of the first amplifier and the power supply input terminal of the first amplifier.

[0007] In particular, in the temperature adaptive current limiting circuit, the power transistor and the first transistor are vertical channel transistors, and the first electrode of the power transistor and the first electrode of the first transistor are prepared on the same substrate.

[0008] In particular, the temperature adaptive current limiting circuit, wherein the adaptive module includes: a second amplifier; a third resistor and a fourth resistor, coupled in series between the negative input terminal of the second amplifier and the first pole of the power transistor; a temperature sensor, whose first pole is coupled to the positive input terminal of the second amplifier, and the second pole is coupled to the first pole of the power transistor; a second transistor, whose control pole is coupled to the output terminal of the second amplifier, the first pole is coupled to the current limiting module, and the second pole is coupled to the node between the third resistor and the fourth resistor; a second current source, coupled to the node between the current limiting module and the first pole of the temperature sensor; and a third current source, coupled between the current limiting module and the negative input terminal of the second amplifier.

[0009] In particular, in the temperature adaptive current limiting circuit, the first electrode of the temperature sensor is coupled to the current limiting module through the second current source.

[0010] In particular, in the temperature adaptive current limiting circuit, when the output voltage of the temperature sensor is greater than the current limiting voltage, the second transistor is turned off, and the changing current output by the adaptive module is zero; the current limiting current is a first current limiting current with a fixed value.

[0011] Particularly, in the temperature adaptive current limiting circuit, the value of the first current limiting current is related to the current value provided by the second current source and the resistance values ​​of the first resistor and the second resistor.

[0012] Particularly, in the temperature adaptive current limiting circuit, the current limiting voltage is related to the current value provided by the first current source and the resistance values ​​of the third resistor and the fourth resistor.

[0013] In particular, in the temperature adaptive current limiting circuit, when the output voltage of the temperature sensor is less than or equal to the current limiting voltage, the second transistor is turned on, and the changing current output by the adaptive module is linearly related to the output voltage of the temperature sensor; the current limiting current is a second current limiting current that is linearly related to the output voltage of the temperature sensor.

[0014] The present application also includes an electronic device, comprising any temperature adaptive current limiting circuit as described above.

[0015] The temperature adaptive current limiting circuit of the power transistor proposed in the present application limits the output current of the power transistor to below the current limiting current based on the heating condition of the power transistor, and the current limiting current value can be adaptively adjusted according to the heating condition of the power transistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Below, the preferred embodiments of the present application will be further described in detail with reference to the accompanying drawings, wherein:

[0017] Figure 1 It is the relationship curve between the output voltage and temperature of the temperature sensitive diode;

[0018] Figure 2 It is the relationship curve between the output voltage of the temperature sensitive diode and the current limiting current of the power transistor;

[0019] Figure 3 It is the relationship curve between the current limit and temperature of the power transistor;

[0020] Figure 4 is a schematic diagram of a partial circuit structure of a power chip according to an embodiment of the present application;

[0021] Figure 5 It is a schematic diagram of the relationship between the current ratio and the current limiting current of the power transistor in different working states and the voltage between the first electrode and the second electrode of the power transistor in the prior art;

[0022] Figure 6 is a schematic diagram of the relationship between the current ratio and the current limiting current and the voltage between the first electrode and the second electrode of the power transistor under different working states according to an embodiment of the present application;

[0023] Figure 7 for Figure 4 A schematic diagram showing the relationship between the output voltage of the temperature sensor of the illustrated embodiment, the current limiting current and the changing current. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] In the following detailed description, reference may be made to the various specification drawings that are part of the present application and are used to illustrate specific embodiments of the present application. In the accompanying drawings, similar reference numerals describe substantially similar components in different figures. The various specific embodiments of the present application are described below in sufficient detail so that a person of ordinary skill in the art with relevant knowledge and skills in the art can implement the technical solutions of the present application. It should be understood that other embodiments may also be used or structural, logical or electrical changes may be made to the embodiments of the present application.

[0026] The technologies, methods and devices known to those skilled in the art may not be discussed in detail, but where appropriate, the technologies, methods and devices shall be considered as part of the specification. The lines between the units in the drawings are only for the convenience of explanation, indicating that at least the units at both ends of the lines are communicating with each other, and are not intended to limit the unconnected units from being unable to communicate. In addition, the number of lines between two units is intended to indicate at least the number of signals involved in the communication between the two units or at least the output terminals, and is not intended to limit the two units to only be able to communicate with each other through the signals shown in the figure.

[0027] A transistor may refer to a transistor of any structure, such as a field effect transistor (FET) or a bipolar junction transistor (BJT). When the transistor is a field effect transistor, it may be hydrogenated amorphous silicon, metal oxide, low temperature polysilicon, organic transistor, etc., depending on the channel material. Depending on whether the carrier is an electron or a hole, it can be divided into an N-type transistor and a P-type transistor, wherein the control electrode refers to the gate of the field effect transistor, the first electrode may be the drain or source of the field effect transistor, the corresponding second electrode may be the source or drain of the field effect transistor, and the control electrode or the third electrode may be the gate; when the transistor is a bipolar transistor, the control electrode refers to the base of the bipolar transistor, the first electrode may be the collector or emitter of the bipolar transistor, the corresponding second electrode may be the emitter or collector of the bipolar transistor, and the control electrode or the third electrode may be the base. The transistor may be manufactured using oxide semiconductors, polycrystalline silicon, amorphous silicon, organic semiconductors, NMOS / PMOS processes, or CMOS processes.

[0028] The present application proposes a temperature-adaptive current limiting circuit for a power transistor, which limits the output current of the power transistor to below the current limiting current based on the heating condition of the power transistor, and the current limiting current value can be automatically adjusted as the heating condition of the power transistor changes. By changing the current limiting current value, the power transistor can maintain a stable temperature during operation, thereby improving the stability and reliability of the power transistor.

[0029] The temperature adaptive current limiting circuit coupled with the power transistor includes a current limiting module and an adaptive module. By using a transistor proportional to the power transistor, the current limiting module can obtain a mirror current proportional to the output current of the power transistor, and control the output current of the power transistor by detecting the magnitude of the mirror current and controlling the voltage of the control electrode of the power transistor.

[0030] Figure 1 It is a curve diagram of the relationship between the output voltage of the temperature-sensitive diode and the temperature. When the temperature-sensitive diode is forward-conducted, as the temperature increases, the output voltage of the temperature-sensitive diode shows a gradual downward trend. The adaptive module coupled to the power transistor includes a temperature sensor such as a temperature-sensitive diode. The temperature sensor in the adaptive module senses the temperature of the power transistor and outputs a corresponding voltage VDT. Taking the temperature sensor as a temperature-sensitive diode as an example, when the temperature of the power chip is lower than the threshold temperature Tth, the output voltage VDT of the temperature sensor is higher than the current-limiting voltage VDTth. Among them, the threshold temperature Tth can be determined according to the temperature resistance of each device in the power chip, mainly the temperature of the power transistor, and the current-limiting voltage VDTth can be the output voltage of the temperature-sensitive diode corresponding to when the temperature of the temperature sensor reaches the threshold temperature Tth.

[0031] Figure 2 It is a curve diagram of the relationship between the output voltage of the temperature-sensitive diode and the current-limiting current of the power transistor. The output voltage VDT of the temperature sensor is higher than the current-limiting voltage VDTth, and the changing current output by the adaptive module is zero. Under the control of the current-limiting module, the current-limiting current Ilimit of the power transistor is a fixed first current-limiting current value Ilimit1, which is related to the properties of the power transistor and the allowed application conditions. When the temperature of the power chip is greater than or equal to the threshold temperature Tth, the output voltage VDT of the temperature sensor is less than or equal to the current-limiting voltage VDTth, and the current-limiting module receives the changing current output by the adaptive module that is linearly related to the output voltage VDT of the temperature sensor, and controls the current-limiting current Ilimit of the power transistor to be a linearly changing second current-limiting current value Ilimit2.

[0032] Figure 3It is a curve diagram of the relationship between the current limiting current and temperature of the power transistor. When the temperature of the power transistor rises, the temperature adaptive current limiting circuit associates the temperature of the power transistor with the current limiting current Ilimit of the power transistor by using the linear relationship between the voltage and temperature when the temperature sensitive diode is forward-conducted. The current limiting current decreases as the temperature of the power transistor increases, and the output current of the power transistor decreases due to the reduction of the current limiting current. The temperature of the power transistor also decreases and a balance is achieved between the heat generation power and the dissipated power of the power chip. Based on the same principle, after the temperature of the power transistor decreases, the current limiting current Ilimit of the power transistor gradually recovers from the second current limiting current value Ilimit2 to the first current limiting current value Ilimit1 under the control of the temperature adaptive current limiting circuit.

[0033] The current limiting module in the temperature adaptive current limiting circuit described below can accurately adjust the current limiting current value of the power transistor when the working state of the power transistor changes from the linear region to the saturation region. It is only for illustrating the working principle of the temperature adaptive current limiting circuit proposed in this application, and is not limited to the structure described below, and may also be other structures.

[0034] Figure 4 FIG. 1 is a schematic diagram of a partial circuit structure of a power chip according to an embodiment of the present application. Figure 4 As shown, the power chip may include a power transistor T21 and a temperature adaptive current limiting circuit 22 .

[0035] According to one embodiment, a first electrode of the power transistor T21 is coupled to an input terminal of the power chip to receive an input voltage Vin from an external circuit, a second electrode is coupled to an output terminal of the power chip to generate an output voltage Vout, and a control electrode thereof is coupled to the temperature adaptive current limiting circuit 22. In one embodiment, the power transistor T21 may be an N-type transistor.

[0036] According to one embodiment, the temperature adaptive current limiting circuit 22 may also be coupled to the input and output ends of the power chip. The temperature adaptive current limiting circuit 22 is configured to regulate the output current of the power transistor T21 based on the temperature change of the power transistor T21, so that the current limiting current of the power transistor changes with the temperature change of the power transistor, thereby preventing the power transistor from being damaged due to continuous temperature rise.

[0037] According to one embodiment, the temperature adaptive current limiting circuit 22 includes a current limiting module 220 and an adaptive module 230. The current limiting module 220 is configured to proportionally mirror the output current of the power transistor T21 to generate a mirror current Isns, and at least receive a variable current Isns1 from the adaptive module 230, and regulate the value of the current Iload output by the power transistor T21 based on the mirror current Isns and the variable current Isns1 of the power transistor, so that the output current Iload of the power transistor T21 does not exceed the current limiting current Ilimit, thereby avoiding damage to the power transistor T21. When the variable current Isns1 is zero, the current limiting current Ilimit of the power transistor T21 is the first current limiting current value Ilimit1.

[0038] According to one embodiment, the current limiting module 220 includes, for example, an N-type transistor T2202, which is proportional to the power transistor T21 and of the same type. According to one embodiment, the current limiting module 220 also includes a resistor R2204. The first electrode of the transistor T2202 is coupled to the first electrode of the power transistor T21, that is, the input end of the power chip. The second electrode of the transistor T2202 is coupled to the second electrode of the power transistor T21, that is, the output end of the power chip, through the resistor R2204, and the resistor R2204 receives the mirror current Isns output by the transistor T2202. The control electrode of the transistor T2202 is coupled to the control electrode of the power transistor T21. The first end of the resistor R2204 and the second electrode of the transistor T2202 are also coupled to the output end of the adaptive module 230, the second end of the resistor R2204 is coupled to the second electrode of the power transistor T21, and the resistor R2204 also receives the change current Isns1 output by the adaptive module 230.

[0039] In one embodiment of the present application, the power transistor T21 and the transistor T2202 may be vertical channel transistors, and the first electrode of the power transistor T21 and the first electrode of the transistor T2202 may be prepared on the same substrate. Compared with traditional transistors, vertical channel transistors have higher switching speeds and greater current driving capabilities, and the accuracy requirements for the current limiting current of the power transistor under the control of the current limiting circuit are also higher. The resistor R2204 is coupled between the second electrode of the transistor T2202 and the output end of the power chip. When the working state of the power transistor T21 changes from the linear region to the saturation region, the accuracy of the current limiting current can be improved, and the output current of the power transistor T21 can be prevented from overshooting, and the resistor R2204 is also separately coupled to the second electrode of the transistor T2202.

[0040] According to one embodiment, the value of the mirror current Isns output by the transistor T2202 depends on the value of the output current Iload of the power transistor T21. The mirror current Isns output by the transistor T2202 and the change current Isns1 output by the adaptive module 230 flow to the output end of the power chip through the resistor R2204.

[0041] According to one embodiment, the current limiting module 220 further includes an amplifier A2205, and a current source I2203 and a charge pump 2207 coupled in series between the positive input terminal of the amplifier A2205 and its power supply input terminal, for providing a voltage Vref to the positive input terminal of the amplifier A2205. The output terminal of the amplifier A2205 is coupled to the control electrode of the transistor T2202, and is coupled to the control electrode of the power transistor T21 as the output terminal of the current limiting module 220. The negative input terminal of the amplifier A2205 is coupled to the node between the second electrode of the transistor T2202 and the first end of the resistor R2204 (point A). The negative input terminal of the amplifier A2205 is also coupled to the output terminal of the adaptive module 230. The amplifier A2205 is configured to provide a voltage VG to the control electrodes of the transistor T2202 and the power transistor T21 based on the voltage values ​​of its positive input terminal and negative input terminal, thereby controlling the current flowing through the transistor T2202 and the power transistor T21. According to one embodiment, the voltage provided by the voltage pump 2207 is higher than the input voltage Vin, for example, 5V higher than the input voltage.

[0042] According to one embodiment, the current limiting module 220 may further include a resistor R2206. The resistor R2206 is coupled between the positive input terminal of the amplifier A2205 and the second electrode of the power transistor T21.

[0043] According to one embodiment, in the current limiting module 220, when the sum of the voltages generated at both ends of the resistor R2204 by the mirror current Isns and the variable current Isns1 flowing through the resistor R2204 gradually approaches the voltage Vref level, the voltage difference between the positive input terminal and the negative input terminal of the amplifier A2205 decreases, and the voltage VG output by the amplifier to the control electrodes of the power transistor T21 and the transistor T2202 decreases. In this case, the current Iload and the mirror current Isns decrease as the voltage of the control electrodes of the power transistor T21 and the transistor T2202 decreases.

[0044] According to one embodiment, when the power transistor T21 operates in the saturation region, the transistor T2202 also operates in the saturation region accordingly. The current Iload output by the power transistor T21 and the current Isns output by the transistor T2202 are respectively

[0045] in, , , , , , , They are respectively the gate-source voltage, channel length modulation factor, drain-source voltage, threshold voltage, width, length and average mobility of the power transistor T21.

[0046]

[0047] in, , , , , , , They are respectively the gate-source voltage, channel length modulation coefficient, drain-source voltage, threshold voltage, width, length and average mobility of transistor T2202.

[0048] In one embodiment, when the potential at point A gradually approaches the voltage Vref, the current limiting module limits the current of the power transistor, and the current ratio KCL of the current Iload and the mirror current Isns is:

[0049]

[0050] in, is the potential at point A, is the overdrive voltage of transistor T2202, , Iref is the current provided by the current source I2203, and Rp is the resistance value of the resistor R2206.

[0051] According to one embodiment, the relationship between the output current Iload of the power transistor T21 and the output current Isns of the transistor T2202 is: When the output current Iload of the power transistor T21 approaches the current limiting current Ilimit, correspondingly, the output current Isns of the transistor T2202 also approaches its current limiting current.

[0052] According to one embodiment, when the power transistor T21 and the transistor T2022 operate in the linear region, , where Ron is the on-resistance of the power transistor T21, and Rn is the resistance of the resistor R2204. In this case, the current ratio of the output current Iload of the power transistor T21 and the mirror current Isns is

[0053] In the prior art, the resistor R2204 is coupled between the first electrode of the transistor T2202 and the input terminal of the power chip. Figure 5Schematic diagram of the relationship between the current ratio and the current limiting current of the power transistor in different working states and the voltage between the first and second electrodes of the power transistor in the prior art. Figure 5 As shown, the current limiting current Ilimit of the power transistor T21 in the linear region increases as the voltage VDS between the first and second electrodes of the power transistor increases, and the value of the current ratio KCL of the power transistor T21 and the transistor T2022 when they work in the linear region is greater than the value of the current ratio of the power transistor T21 and the transistor T2022 when they work in the saturation region. When the working state of the power transistor changes from the linear region to the saturation region, the current limiting current Ilimit of the power transistor T21 drops as the voltage VDS between the first and second electrodes of the power transistor T21 increases, resulting in an overshoot of the output current of the power transistor T21.

[0054] Figure 6 The figure is a schematic diagram of the relationship between the current ratio and the current limiting current and the voltage between the first and second electrodes of the power transistor under different working states according to an embodiment of the present application. In order to avoid current overshoot when the working state of the power transistor T21 changes, its current limiting current can be smoothly converted, that is, the current ratio of the power transistor T21 and the transistor T2022 when working in the linear region is equal to the current ratio of the power transistor T21 and the transistor T2022 when working in the saturation region.

[0055]

[0056] At this time, by adjusting the current value provided by the current source I2203 and the resistance values ​​of the resistors R2204 and R2206, a high current limiting value can be avoided when the voltage VDS between the first and second electrodes of the power transistor is close to the saturation region, thereby preventing the output current of the power transistor from overshooting and improving the accuracy of the output current control of the power transistor T21.

[0057] According to one embodiment, the current limiting module 220 coupled to the adaptive module 230 may also include other forms of current limiting circuits coupled to the power transistor T21 .

[0058] According to one embodiment, the temperature adaptive current limiting circuit 22 further includes an adaptive module 230 coupled between the first pole and the second pole of the power transistor T21. The adaptive module 230 is configured to generate a change current Isns1 for regulating the current limiting current Ilimit of the power transistor T21 based on the temperature of the power transistor T21, and output it to the current limiting module 220. The adaptive module 230 cooperates with the current limiting module 220 to change the current limiting current Ilimit of the power transistor T21 when the temperature of the power transistor T21 is at different levels, thereby ensuring that the power transistor T21 can work safely.

[0059] According to one embodiment, the adaptive module 230 includes a temperature sensor D2301 and a current source I2302. The first electrode of the temperature sensor D2301 is coupled to a node between the current source I2302 and the voltage pump 2207 through the current source I2302, and the second electrode thereof is coupled to the first electrode of the power transistor T21. According to one embodiment, the temperature sensor D2301 may include a temperature sensitive diode.

[0060] According to one embodiment, the adaptive module 230 further includes an amplifier A2303 and a current source I2304. The positive input terminal of the amplifier A2303 is coupled to the first electrode of the temperature sensor D2301, and the negative input terminal is coupled to the node between the current source I2302 and the voltage pump 2207 through the current source I2304. According to one embodiment, the adaptive module 230 further includes a resistor R2305 and a resistor R2306 coupled in series between the negative input terminal of the amplifier A2303 and the second electrode of the temperature sensor D2301.

[0061] According to one embodiment, the adaptive module 230 further includes a transistor T2307. The first electrode of the transistor T2307 is coupled to the negative input terminal of the amplifier A2205 as the output terminal of the adaptive module 230, and outputs the variable current Isns1 to the current limiting module. The control electrode of the transistor T2307 is coupled to the output terminal of the amplifier A2303, and the second electrode is coupled to the node between the resistor R2305 and the resistor R2306. The transistor T2307 can be, for example, a P-type transistor.

[0062] In another embodiment, for a current limiting circuit with a different structure, the transistor T2307 may also be, for example, an N-type transistor. The first electrode of the temperature sensor D2301 may be coupled to the negative input terminal of the amplifier A2303. The positive input terminal of the amplifier A2303 is coupled to the node between the current source I2302 and the voltage pump 2207 through the current source I2304, and the resistors R2305 and R2306 are coupled in series between the positive input terminal of the amplifier A2303 and the second electrode of the temperature sensor D2301.

[0063] According to one embodiment, when the temperature of the power chip is less than the threshold temperature Tth, the power chip operates in a low temperature environment. The output voltage VDT of the temperature sensor D2301 is greater than the current limiting voltage VDTth, the voltage at the positive input terminal of the amplifier A2303 is higher than the voltage at the negative input terminal, and the amplifier A2303 outputs a high voltage. At this time, the transistor T2307 is turned off, and the change current Isns1 output by its second pole is zero.

[0064] According to one embodiment, the current limiting voltage VDTth is , where I3 is the current value provided by the current source I2304, and R3 and R4 are the resistance values ​​of the resistor R2305 and the resistor R2306 respectively.

[0065] According to an embodiment, when designing the temperature adaptive current limiting circuit, the value of the current limiting voltage VDTth can be adjusted by adjusting the values ​​of the resistors R2305 and R2306 and the value of the current provided by the current source I2304.

[0066] According to one embodiment, when the current Iload value increases and approaches the current limiting current Ilimit, the voltage generated when the mirror current Isns flows through the resistor R2204 is close to the voltage Vref at the positive input terminal of the amplifier A2205, that is, The current limiting module 220 controls the power transistor T21 so that the output current Iload does not exceed the first current limiting value Ilimit1.

[0067]

[0068] In one embodiment, during the circuit design stage, the first current limiting current value is adjusted by adjusting the values ​​of the resistors R2206 and R2204 in the current limiting module 220 and the current value provided by the current source I2203 .

[0069] According to another embodiment of the present application, when the temperature of the power chip rises and is greater than or equal to the threshold temperature Tth, the power chip operates in a high temperature environment. The output voltage VDT of the temperature sensor D2301 decreases as the temperature rises and is less than or equal to the current limiting voltage VDTth, the voltage at the positive input terminal of the amplifier A2303 is lower than the voltage at the negative input terminal, the amplifier A2303 outputs a low voltage, and the transistor T2307 is turned on. The first pole of the transistor T2307 outputs a changing current Isns1 that is linearly related to the output voltage VDT of the temperature sensor.

[0070]

[0071] According to one embodiment of the present application, when the current Iload and the mirror current Isns increase with the increase of the temperature of the power transistor, the sum of the voltages generated when the mirror current Isns and the variable current Isns1 flow through the resistor R2204 gradually approaches the voltage Vref at the positive input terminal of the amplifier A2205, and the mirror current Isns output by the transistor T2202 is The voltage VG output by the amplifier A2205 decreases, so that the current Iload output by the power transistor T21 and the mirror current Isns output by the transistor T2202 decrease due to the decrease in the control electrode voltage, thereby limiting the output current of the power transistor and reducing the temperature of the power transistor. In this case, the current limiting current Ilimit of the power transistor T21 is a second current limiting current value Ilimit2 that is linearly related to the output voltage VDT of the temperature sensor D2301, which can be expressed as

[0072] Figure 7 for Figure 4 Schematic diagram of the relationship between the output voltage of the temperature sensor of the embodiment shown, the current limiting current and the changing current. According to one embodiment, the current limiting process of the power transistor is divided into two stages.

[0073] In the first stage, the temperature of the power chip is lower than the threshold temperature Tth, and the value of the output voltage VDT of the temperature sensor is higher than the current limiting voltage VDTth. In this process, the value of the variable current Isns1 output by the adaptive module is zero, and the output current Ioad of the power transistor under the control of the current limiting module is lower than the fixed first current limiting current value Ilimit1.

[0074] In the second stage, the temperature of the power chip rises and is greater than or equal to the threshold temperature Tth, and the value of the output voltage VDT of the temperature sensor is less than or equal to the current limiting voltage VDTth. In this process, the value of the changing current Isns1 output by the adaptive module increases as the output voltage VDT of the temperature sensor decreases. The current limiting module receives the changing current Isns1 from the adaptive module and controls the current limiting current Ilimit of the power transistor to be a second current limiting current value Ilimit2 which is linearly related to the output voltage VDT of the temperature sensor.

[0075] The present application also provides an electronic device, which includes the power transistor as described above, and the temperature adaptive current limiting circuit in any of the above embodiments.

[0076] The present application provides a simple structure, high-precision temperature adaptive current limiting circuit. This circuit is applied in, for example, a power chip to limit the output current of a power transistor when the temperature of the power transistor rises. The current limiting capability of the temperature adaptive current limiting circuit is related to the temperature of the power transistor, and the current limiting current value can be automatically adjusted with the temperature, ensuring that the power transistor works safely at a stable temperature, and improving the reliability and adaptive capability of the circuit.

[0077] The above embodiments are only used to illustrate the present application, and are not intended to limit the present application. Ordinary technicians in the relevant technical field may make various changes and modifications without departing from the scope of the present application. Therefore, all equivalent technical solutions should also fall within the scope disclosed in the present application.

Claims

1. A temperature adaptive current limiting circuit for a power transistor, comprising: An adaptive module, coupled between the first electrode and the second electrode of the power transistor, configured to generate a variable current for regulating the current limiting current based on the temperature of the power transistor; A current limiting module, coupled between the first and second electrodes of the power transistor and coupled to the output end of the adaptive module, wherein the output end is coupled to the control electrode of the power transistor, and configured to proportionally mirror the output current of the power transistor to generate a mirror current and receive a change current output by the adaptive module, and when the temperature of the power transistor changes, the voltage provided to the control electrode of the power transistor is controlled based on the mirror current and the change current; The temperature adaptive current limiting circuit limits the output current of the transistor to, When the temperature of the power transistor is lower than a threshold temperature, the limiting current of the power transistor is a first current limiting current with a fixed value and is determined by the current limiting module; when the temperature of the power transistor is greater than or equal to the threshold temperature, the limiting current of the power transistor is a second current limiting current value with a linear change and the change slope is determined by the adaptive module.

2. The temperature adaptive current limiting circuit according to claim 1, wherein: The current limiting module comprises: A first transistor (T2202) and a first resistor (R2204), wherein a first electrode of the first transistor (T2202) is coupled to a first electrode of the power transistor, a second electrode of the first transistor (T2202) is coupled to a second electrode of the power transistor through the first resistor (R2204), and a control electrode of the first transistor (T2202) is coupled to a control electrode of the power transistor; A first amplifier (A2205) and a second resistor (R2206), wherein a negative input terminal of the first amplifier (A2205) is coupled to a node where the first resistor (R2204) and the second electrode of the first transistor (T2202) are coupled, an output terminal of the first amplifier (A2205) is coupled to a control electrode of the power transistor, and a positive input terminal of the first amplifier (A2205) is coupled to the second electrode of the power transistor through the second resistor (R2206); A first current source (I2203) and a voltage pump (2207) are coupled in series with each other between a positive input terminal of the first amplifier (A2205) and a power supply input terminal of the first amplifier (A2205).

3. According to the temperature adaptive current limiting circuit of claim 2, the value of the first current limiting current is related to the current value provided by the first current source (I2203) and the resistance values ​​of the first resistor (R2204) and the second resistor (R2206).

4. The temperature adaptive current limiting circuit according to claim 3, wherein: The power transistor and the first transistor (T2202) are vertical channel transistors, and the first electrode of the power transistor and the first electrode of the first transistor (T2202) are prepared on the same substrate.

5. The temperature adaptive current limiting circuit according to claim 1 or 3, wherein: The adaptive module comprises: Second amplifier (A2303); A third resistor (R2305) and a fourth resistor (R2306) are coupled in series with each other between the negative input terminal of the second amplifier (A2303) and the first electrode of the power transistor; a temperature sensor having a first electrode coupled to the positive input terminal of the second amplifier (A2303) and a second electrode coupled to the first electrode of the power transistor; a second transistor (T2307), a control electrode coupled to the output end of the second amplifier (A2303), a first electrode coupled to the current limiting module, and a second electrode coupled to a node between the third resistor (R2305) and the fourth resistor (R2306); A second current source (I2302) coupled to a node between the current limiting module and the first electrode of the temperature sensor; and The third current source (I2304) is coupled between the current limiting module and the negative input terminal of the second amplifier (A2303).

6. The temperature adaptive current limiting circuit according to claim 5, wherein: The first electrode of the temperature sensor is coupled to the current limiting module through the second current source (I2302).

7. The temperature adaptive current limiting circuit according to claim 6, wherein: When the output voltage of the temperature sensor is greater than the current limiting voltage, the second transistor (T2307) is turned off, and the changing current output by the adaptive module is zero; The current limiting current is a first current limiting current with a fixed value.

8. The temperature adaptive current limiting circuit according to claim 7, wherein the current limiting voltage is related to the current value provided by the third current source (I2304) and the resistance values ​​of the third resistor (R2305) and the fourth resistor (R2306).

9. The temperature adaptive current limiting circuit according to claim 8, wherein: When the output voltage of the temperature sensor is less than or equal to the current limiting voltage, the second transistor (T2307) is turned on, and the changing current output by the adaptive module is linearly related to the output voltage of the temperature sensor; The current limiting current is a second current limiting current that has a linear relationship with the output voltage of the temperature sensor.

10. An electronic device comprising the temperature adaptive current limiting circuit as claimed in any one of claims 1 to 9.

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