Over-temperature detection module, constant current control circuit and test method of over-temperature detection module

Abstract

The invention provides an over-temperature detection module, a constant current control circuit and a test method of the over-temperature detection module, and the over-temperature detection module comprises an operational amplification unit which generates a current signal which linearly changes along with the difference between a temperature detection voltage and a positive temperature coefficient voltage when the temperature detection voltage is smaller than the positive temperature coefficient voltage; the mode switching unit is used for interchanging the corresponding relation between the input signal and the output signal of the operational amplification unit so as to realize the interchange between a normal working mode and a test mode; the voltage difference output unit is used for generating and outputting a voltage difference between the temperature detection voltage and the positive temperature coefficient voltage based on an output signal of the operational amplification unit; and the first trimming unit acts on the input end of the positive temperature coefficient voltage or the temperature detection voltage and trims the voltage of the input end, so that the voltage difference falls into a preset voltage difference range. According to the invention, test pins and test steps are reduced, and peripheral programs are simplified; the high consistency of an over-temperature current reduction starting point can be realized, the consistency of an over-temperature turn-off point can be ensured, and the method is suitable for a constant-current control system.

Description

Technical Field

[0001] The present invention relates to the field of integrated circuits, and in particular to an over-temperature detection module, a constant current control circuit and a test method for the over-temperature detection module. Background Art

[0002] The starting inflection point of the over-temperature current reduction circuit is an important parameter of the chip's electrical characteristics. Since the over-temperature detection circuit generally sets the starting inflection point of the current reduction to a high temperature, such as above 100°C, due to the limitations of the test environment, it is impossible to measure the over-temperature current reduction inflection point of each chip one by one in the actual mass production test. The inflection point and drift range can only be estimated through simulation and calculation; affected by factors such as process drift, the simulation value and the measured value will deviate, and there will be problems with poor accuracy and consistency. With the application of peripheral thermistors, there are often higher requirements for the consistency of over-temperature current reduction.

[0003] Therefore, it is necessary to test the over-temperature detection circuit to pre-determine the over-temperature starting and ending points, and then improve the consistency of the over-temperature starting and ending points through adjustment; accordingly, test pins need to be added to the layout. The more test pins, the higher the cost and the more complicated the peripheral test procedures. How to reduce the number of test pins, reduce costs, and simplify peripheral test procedures has become one of the technical problems that technicians in this field need to solve urgently.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide an over-temperature detection module, a constant current control circuit and a testing method for the over-temperature detection module, so as to solve the problems in the prior art of the over-temperature current reduction circuit having many test pins for the starting inflection point, high cost, and complex peripheral testing procedures.

[0006] In order to achieve the above-mentioned object and other related objects, the present invention provides an over-temperature detection module, which at least includes:

[0007] An operational amplifier unit, a mode switching unit, a pressure difference output unit and a first trimming unit;

[0008] The input end of the operational amplifier unit receives a positive temperature coefficient voltage and a temperature detection voltage respectively, and when the temperature detection voltage is less than the positive temperature coefficient voltage, generates a current signal that changes linearly with the difference between the temperature detection voltage and the positive temperature coefficient voltage;

[0009] The mode switching unit is connected to the operational amplifier unit, and exchanges the corresponding relationship between the input signal and the output signal of the operational amplifier unit to achieve the exchange between the normal working mode and the test mode;

[0010] The voltage difference output unit is connected between the output end of the operational amplifier unit and the test pin, and generates and outputs the voltage difference between the temperature detection voltage and the positive temperature coefficient voltage based on the output signal of the operational amplifier unit;

[0011] The first trimming unit acts on the input end of the positive temperature coefficient voltage or the temperature detection voltage to trim the input end voltage so that the voltage difference between the two input ends of the operational amplifier unit falls within a preset voltage difference range.

[0012] Optionally, the operational amplifier unit includes a first bias circuit, a first resistor, a second resistor, a first PMOS transistor, a second PMOS transistor, a first NMOS transistor, a second NMOS transistor, a third NMOS transistor and a fourth NMOS transistor, and the mode switching unit includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch and a sixth switch;

[0013] The first bias circuit provides a first bias current, a second bias current and a third bias current; the first ends of the first resistor and the second resistor are connected to the first bias current; the second end of the first resistor is grounded via the first PMOS tube and the first NMOS tube in sequence; the second end of the second resistor is grounded via the second PMOS tube and the second NMOS tube in sequence; the first NMOS tube is connected to the gate of the second NMOS tube; the first switch is connected between the drain and the gate of the first NMOS tube, and the second switch is connected between the drain and the gate of the second NMOS tube; the positive temperature coefficient voltage is connected to the first PMOS tube The temperature detection voltage is connected to the gate of the second PMOS tube; the second bias current is loaded on the second end of the first resistor; the third bias current is loaded on the second end of the second resistor via the third switch, and is loaded on the second end of the first resistor via the fourth switch; the drain of the third NMOS tube is connected to the third bias current, and the source is grounded; the gate of the third NMOS tube is connected to the drain of the second PMOS tube via the fifth switch, and is connected to the drain of the first PMOS tube via the sixth switch; the gate of the fourth NMOS tube is connected to the gate of the third NMOS tube, the source is grounded, and the drain outputs the current signal.

[0014] Optionally, the operational amplifier unit includes a second bias circuit, a third resistor, a fourth resistor, a third PMOS tube, a fourth PMOS tube, a fifth NMOS tube, a sixth NMOS tube, a seventh NMOS tube and an eighth NMOS tube;

[0015] The second bias circuit provides a fourth bias current, a fifth bias current and a sixth bias current; the first ends of the third resistor and the fourth resistor are connected to the fourth bias current; the second end of the third resistor is grounded via the third PMOS tube and the fifth NMOS tube in sequence; the second end of the fourth resistor is grounded via the fourth PMOS tube and the sixth NMOS tube in sequence; the gate and drain of the fifth NMOS tube are connected, and are also connected to the gate of the sixth NMOS tube; the fifth bias current is loaded on the second end of the third resistor, and the sixth bias current is loaded on the second end of the fourth resistor; the drain of the seventh NMOS tube is connected to the sixth bias current, the gate is connected to the drain of the fourth PMOS tube, and the source is grounded; the gate of the eighth NMOS tube is connected to the gate of the seventh NMOS tube, the source is grounded, and the drain outputs the current signal.

[0016] Optionally, the mode switching unit includes a seventh switch, an eighth switch, a ninth switch and a tenth switch; the positive temperature coefficient voltage is connected to the gates of the third PMOS tube and the fourth PMOS tube via the seventh switch and the eighth switch, respectively, and the temperature detection voltage is connected to the gates of the third PMOS tube and the fourth PMOS tube via the ninth switch and the tenth switch, respectively.

[0017] More optionally, the voltage difference output unit includes a ninth NMOS tube, a fifth PMOS tube, a sixth PMOS tube and a fifth resistor; the source of the ninth NMOS tube is grounded, the gate is connected to the output end of the operational amplifier unit, and the drain is connected to the drain of the fifth PMOS tube; the gate and drain of the fifth PMOS tube are connected, and the source is connected to the power supply; the source of the sixth PMOS tube is connected to the power supply, the gate is connected to the gate of the fifth PMOS tube, and the drain is connected to the test pin and grounded via the fifth resistor.

[0018] More optionally, the over-temperature detection module also includes a second trimming unit, which is connected to the output end of the operational amplifier unit and trims the output current of the over-temperature detection module so that the output current of the over-temperature detection module falls within a preset current range.

[0019] In order to achieve the above-mentioned object and other related objects, the present invention further provides a constant current control circuit, which at least includes:

[0020] Operational amplifier module and the above-mentioned over-temperature detection module;

[0021] The first input terminal of the operational amplifier module receives a current sampling signal, the second input terminal receives a reference signal, and outputs a switch control signal; the over-temperature detection module is connected to the first input terminal or the second input terminal of the operational amplifier module, and generates a linearly changing current signal when it is detected that the temperature exceeds a preset value; wherein, when the over-temperature detection module is connected to the first input terminal of the operational amplifier module, a resistor is further connected in series between the first input terminal of the operational amplifier module and the current sampling signal.

[0022] In order to achieve the above-mentioned object and other related objects, the present invention further provides a constant current control circuit, which at least comprises:

[0023] Comparison module, pulse width modulation module and the above-mentioned over-temperature detection module;

[0024] The first input terminal of the comparison module receives a current sampling signal, the second input terminal receives a reference signal, and outputs a comparison result;

[0025] The pulse width modulation module is connected to the output end of the comparison module, and adjusts the pulse width based on the comparison result to obtain a switch control signal;

[0026] The over-temperature detection module is connected to the first input terminal or the second input terminal of the comparison module, and generates a linearly changing current signal when it is detected that the temperature exceeds a preset value;

[0027] Wherein, when the over-temperature detection module is connected to the first input terminal of the comparison module, a resistor is further connected in series between the first input terminal of the comparison module and the current sampling signal.

[0028] In order to achieve the above-mentioned object and other related objects, the present invention further provides a constant current control system, characterized in that the constant current control system at least comprises:

[0029] Power switch tube, sampling circuit and the above constant current control circuit;

[0030] The drain of the power switch tube is connected to the load, and the source is grounded via the sampling circuit;

[0031] The input end of the constant current control circuit is connected to the output end of the sampling circuit, and the output end is connected to the gate of the power switch tube.

[0032] To achieve the above-mentioned object and other related objects, the present invention further provides a method for testing an over-temperature detection module, the method for testing an over-temperature detection module comprising:

[0033] Providing at least two chips, each of which is provided with the above-mentioned over-temperature detection module;

[0034] Switching the mode of the over-temperature detection module from the normal working mode to the test mode; wherein, in the normal working mode, the mode switching unit configures the positive temperature coefficient voltage to be connected to the non-inverting input terminal of the operational amplifier unit, and configures the temperature detection voltage to be connected to the inverting input terminal of the operational amplifier unit; in the test mode, the mode switching unit configures the temperature detection voltage to be connected to the non-inverting input terminal of the operational amplifier unit, and configures the positive temperature coefficient voltage to be connected to the inverting input terminal of the operational amplifier unit;

[0035] At normal temperature, the voltage difference between the temperature detection voltage and the positive temperature coefficient voltage is obtained based on the output signal of the voltage difference output unit; if the voltage difference does not fall within the preset voltage difference range, the corresponding positive temperature coefficient voltage input terminal or the temperature detection voltage input terminal is adjusted until the voltage difference between the two input terminals of each operational amplifier unit falls within the preset voltage difference range, thereby making the starting inflection point of the over-temperature drop current of each chip consistent.

[0036] Optionally, the testing method of the over-temperature detection module also includes: detecting the output current of the operational amplifier unit in each chip, and if the output current does not fall within a preset current range, adjusting the output current until the output current of each operational amplifier unit falls within the preset current range, thereby keeping the over-temperature shutdown point of each chip consistent.

[0037] As described above, the over-temperature detection module, the constant current control circuit and the test method of the over-temperature detection module of the present invention have the following beneficial effects:

[0038] 1. The over-temperature detection module of the present invention can directly obtain the voltage difference of the input signal through the test mode with only one test pin, thereby reducing the test pins and test steps and simplifying the peripheral program.

[0039] 2. The input and output of the over-temperature detection module of the present invention change linearly, and can be used in an over-temperature current reduction circuit. By adjusting the circuit, a high degree of consistency of the over-temperature current reduction starting point can be achieved.

[0040] 3. The present invention also adds an additional adjustment to the output current of the operational amplifier unit to further ensure the consistency of the over-temperature shutdown point.

[0041] 4. The present invention is applicable to a constant current control system, which can be a linear constant current or a switch-type PWM constant current. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Shown is a schematic diagram of the structure of an over-temperature detection circuit with a trimming function.

[0043] Figure 2 Display as Figure 1 Schematic diagram of the key node waveforms of the over-temperature detection circuit.

[0044] Figure 3 Shown is a distribution diagram of the starting inflection point of the over-temperature drop current.

[0045] Figure 4 Shown is a structural schematic diagram of the over-temperature detection module of the present invention.

[0046] Figure 5 It is a schematic diagram showing the structure of the over-temperature detection module of the present invention in a normal working mode.

[0047] Figure 6 It is a schematic diagram showing the structure of the over-temperature detection module of the present invention in the test mode.

[0048] Figure 7 Another structural schematic diagram of the over-temperature detection module of the present invention is shown.

[0049] Figure 8 Shown is a structural schematic diagram of a constant current control circuit and a constant current control system of the present invention.

[0050] Fig. 9 Shown is a structural schematic diagram of another constant current control circuit and constant current control system of the present invention.

[0051] Fig.10 Shown is a structural schematic diagram of another constant current control circuit and constant current control system of the present invention.

[0052] Component number description

[0053] 1 Overtemperature detection circuit

[0054] 11 Operational amplifier unit

[0055] 12 Output current linear regulation unit

[0056] 13 Output Unit

[0057] 14 Adjustment Unit

[0058] 2 Constant current control circuit

[0059] 21 Over temperature detection module

[0060] 211 Operational Amplifier Unit

[0061] 211a First bias circuit

[0062] 211b Second bias circuit

[0063] 212 Mode switching unit

[0064] 213 Differential pressure output unit

[0065] 214 First Adjustment Unit

[0066] 215 Second Adjustment Unit

[0067] 22 Operational amplifier module

[0068] 23 Comparison module

[0069] 24 Pulse Width Modulation Module

[0070] 3 Sampling Circuit DETAILED DESCRIPTION

[0071] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0072] See also Figures 1 to 10 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0073] like Figure 1 The figure shows an over-temperature detection circuit 1 with a trimming function, comprising: an operational amplifier unit 11, an output current linear adjustment unit 12, an output unit 13 and a trimming unit 14. The input end of the operational amplifier unit 11 receives a positive temperature coefficient voltage VPTAT and a temperature detection voltage VBE respectively, and amplifies and outputs the difference between the positive temperature coefficient voltage VPTAT and the temperature detection voltage VBE. The output current linear adjustment unit 12 is connected to the output end of the operational amplifier unit 11, and when the temperature detection voltage VBE is less than the positive temperature coefficient voltage VPTAT, a current signal that changes linearly with the difference between the temperature detection voltage and the positive temperature coefficient voltage is generated. The output unit 13 is connected to the output end of the output current linear adjustment unit 12, and proportionally adjusts the current output by the output current linear adjustment unit 12. The first trimming unit 14 acts on the input end of the positive temperature coefficient voltage or the temperature detection voltage, and trims the input end voltage so that the voltage difference between the two input ends of the operational amplifier unit falls within a preset voltage difference range.

[0074] like Figure 2As shown, due to the effect of transistors M8 and M10, the over-temperature drop current starting inflection point TSC is at the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT, and the output current Itsc of the output unit 113 is controlled to change linearly with the input voltage difference, satisfying: I TSC =n*Id=n*I MN10 =n*(Ib2-0.5*Ia). In actual tests, both input terminals of the operational amplifier unit 11 have drift. It is found through research that the over-temperature drop current starting inflection point TSC is actually a Gaussian distribution, such as Figure 3 As shown; based on the adjustment of the adjustment unit 14, the voltage difference between the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT of each over-temperature drop current circuit at room temperature (for example, 25°C) is equal, so that the temperature point when the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT are equal, that is, the over-temperature drop current starting inflection point TSC is consistent. Figure 1 As shown, the test pins PAD1 and PAD2 are respectively set at the two input terminals of the operational amplifier unit 11 to obtain the corresponding voltage, and then the difference is calculated through an external program to obtain the voltage difference between the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT, thereby achieving adjustment. The above scheme requires two test pins; on this basis, the present invention further reduces the number of test pins and simplifies the peripheral program. The specific scheme is as follows.

[0075] Embodiment 1

[0076] like Figure 4 As shown, this embodiment provides an over-temperature detection module 21, and the over-temperature detection module 21 includes:

[0077] The operational amplifier unit 211 , the mode switching unit 212 , the pressure difference output unit 213 and the first trimming unit 214 .

[0078] like Figure 4 As shown, the input end of the operational amplifier unit 211 receives the positive temperature coefficient voltage VPTAT and the temperature detection voltage VBE respectively. When the temperature detection voltage VBE is less than the positive temperature coefficient voltage VPTAT, a current signal Itsc is generated that changes linearly with the difference between the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT (i.e., VBE-VPTAT).

[0079] like Figure 4 As shown, the mode switching unit 212 is connected to the operational amplifier unit 211 and exchanges the corresponding relationship between the input signal and the output signal of the operational amplifier unit 211 to achieve the exchange between the normal working mode and the test mode.

[0080] Specifically, in this embodiment, the operational amplifier unit 211 includes a first bias circuit 211a, a first resistor R1, a second resistor R2, a first PMOS transistor MP1, a second PMOS transistor MP2, a first NMOS transistor MN1, a second NMOS transistor MN2, a third NMOS transistor MN3, and a fourth NMOS transistor MN4. The mode switching unit 212 includes a first switch SW1, a second switch SW2, a third switch SW3, a fourth switch SW4, a fifth switch SW5, and a sixth switch SW6.

[0081] Wherein, the first bias circuit 211a provides a first bias current I1, a second bias current I2 and a third bias current I3; as an example, the first bias circuit 211a includes a seventh PMOS tube MP7, an eighth PMOS tube MP8, a ninth PMOS tube MP9 and a tenth PMOS tube MP10, the sources of the seventh to tenth PMOS tubes are all connected to the power supply VDD, and the gates are connected together; the drain of the seventh PMOS tube MP7 is connected to the gate and receives the bias signal IB; the drain of the eighth PMOS tube MP8 outputs the second bias current I2, the drain of the ninth PMOS tube MP9 outputs the first bias current I1, and the drain of the tenth PMOS tube MP10 outputs the third bias current I3. The first ends of the first resistor R1 and the second resistor R2 are connected to the first bias current I1. In this example, the resistance values ​​of the first resistor R1 and the second resistor R2 are equal. The second end of the first resistor R1 is grounded via the first PMOS tube MP1 and the first NMOS tube MN1 in sequence. The second end of the second resistor R2 is grounded via the second PMOS transistor MP2 and the second NMOS transistor MN2 in sequence. The first PMOS transistor MP1 and the second PMOS transistor MP2 are used as input pairs, the positive temperature coefficient voltage VPTAT is connected to the gate of the first PMOS transistor MP1, and the temperature detection voltage VBE is connected to the gate of the second PMOS transistor MP2. The gates of the first NMOS transistor MN1 and the second NMOS transistor MN2 are connected together (in this example, the width-to-length ratio of the first NMOS transistor MN1 to the second NMOS transistor MN2 is set to 1:1). The first switch SW1 is connected between the drain and the gate of the first NMOS transistor MN1, and the second switch SW2 is connected between the drain and the gate of the second NMOS transistor MN2. The second bias current I2 is loaded on the second end of the first resistor R1 (i.e., the source of the first PMOS transistor MP1); the third bias current I3 is loaded on the second end of the second resistor R2 (i.e., the source of the second PMOS transistor MP2) via the third switch SW3, and is also loaded on the second end of the first resistor R1 via the fourth switch SW4, that is, the bias current I3 is loaded on the first end of the first resistor R1 or the first end of the second resistor R2 by the control of the third switch SW3 and the fourth switch SW4. The drain of the third NMOS transistor MN3 is connected to the third bias current I3, and the source is grounded. The gate of the third NMOS transistor MN3 is connected to the drain of the second PMOS transistor MP2 via the fifth switch SW5, and is also connected to the drain of the first PMOS transistor MP1 via the sixth switch SW6, that is, the polarity of the output signal is determined by the control of the fifth switch SW5 and the sixth switch SW6.The gate of the fourth NMOS transistor MN4 is connected to the gate of the third NMOS transistor MN3 , the source is grounded, and the drain outputs the current signal Itsc.

[0082] It should be noted that any current signal Itsc that can generate a linear change with the difference between the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT (i.e., VBE-VPTAT) when the temperature detection voltage VBE is less than the positive temperature coefficient voltage VPTAT (the relationship between the output current signal and the input signal is shown in FIG. Figure 2 ) are applicable to the operational amplifier unit 211 of the present invention, and the current signal Itsc may also be a pull-down current, which is not limited to this embodiment. Any circuit structure that can interchange the corresponding relationship between the input signal and the output signal of the operational amplifier unit 211 to achieve the interchange of the normal working mode and the test mode is applicable to the mode switching unit 212 of the present invention, which is not limited to this embodiment.

[0083] like Figure 4 As shown, the voltage difference output unit 213 is connected between the output end of the operational amplifier unit 211 and the test pin PAD, and generates and outputs the voltage difference VBE-VPTAT between the temperature detection voltage and the positive temperature coefficient voltage based on the output signal of the operational amplifier unit 211.

[0084] Specifically, in this embodiment, the voltage difference output unit 213 includes a ninth NMOS transistor MN9, a fifth PMOS transistor MP5, a sixth PMOS transistor MP6 and a fifth resistor R5. The source of the ninth NMOS transistor MN9 is grounded, the gate is connected to the gates of the third NMOS transistor MN3 and the fourth NMOS transistor MN4 (in this example, the width-to-length ratio of the third NMOS transistor MN3, the fourth NMOS transistor MN4 and the ninth NMOS transistor MN9 is set to m:n:m), and the drain is connected to the drain of the fifth PMOS transistor MP5; the source of the fifth PMOS transistor MP5 is connected to the power supply VDD, and the gate and the drain are connected together; the source of the sixth PMOS transistor MP6 is connected to the power supply VDD, the gate is connected to the gate of the fifth PMOS transistor MP5, and the drain is grounded via the fifth resistor R5; the drain of the sixth PMOS transistor MP6 is connected to the test pin PAD, which is used to obtain the voltage difference VBE-VPTAT between the temperature detection voltage and the positive temperature coefficient voltage.

[0085] It should be noted that any circuit structure capable of outputting the voltage difference VBE-VPTAT between the temperature detection voltage and the positive temperature coefficient voltage in the operational amplifier unit 211 is applicable to the voltage difference output unit 213 of the present invention, and is not limited to this embodiment.

[0086] like Figure 4 As shown, the first trimming unit 214 acts on the input end of the positive temperature coefficient voltage VPTAT or the temperature detection voltage VBE to trim the input end voltage so that the voltage difference between the two input ends of the operational amplifier unit 211 falls within a preset voltage difference range, thereby making the input and output of the over-temperature detection module 21 change linearly, and achieving higher consistency of the over-temperature reduction current starting inflection point for different circuits.

[0087] It should be noted that the preset voltage difference range can be set according to parameters such as device characteristics and manufacturing process, which will not be described in detail here.

[0088] Specifically, as an example, the first trimming unit includes N trimming resistors, switches and a trimming control unit, where N is a natural number greater than or equal to 2. The trimming resistors are connected in series in sequence; each switch corresponds to each trimming resistor one by one, and is respectively connected in parallel to the two ends of the corresponding trimming resistor. The trimming control unit is used to generate control signals for each switch, and a fuse is provided inside it. The corresponding control signal is obtained through the fuse, and the number of resistors and the corresponding resistance value in the resistor string formed by the trimming resistor are adjusted by the control of the switch; further, the resistance value of each trimming resistor is in a 2-fold increasing relationship in sequence, that is, the ratio of the resistance value is set to 1:2:4:8... In actual use, the trimming resistors can also be set in parallel. At this time, each switch corresponds to each trimming resistor one by one, and is respectively connected in series with the corresponding trimming resistor, which will not be described one by one here. When the first trimming unit is set at the input end of the positive temperature coefficient voltage VPTAT, the positive temperature coefficient voltage VPTAT is obtained by the first positive temperature coefficient current acting on the voltage-dividing resistor (the first positive temperature coefficient current flows through the voltage-dividing resistor, and the positive temperature coefficient voltage VPTAT is generated on the voltage-dividing resistor); each trimming resistor is set between the input end of the positive temperature coefficient voltage VPTAT and the ground, and is connected in series with the voltage-dividing resistor at the input end of the positive temperature coefficient voltage (the position is not limited, as long as the series relationship is achieved). When the first trimming unit is set at the input end of the temperature detection voltage VBE, the temperature detection voltage VBE is obtained by the second positive temperature coefficient current acting on the PN junction of a diode (as an example, a bipolar transistor is used to implement it) (the second positive temperature coefficient current flows through the bipolar transistor with a diode structure, and the temperature detection voltage VBE is generated on the bipolar transistor); each trimming resistor is connected in series between the input end of the temperature detection voltage and the temperature detection device (the anode of the diode D). Any circuit structure that can adjust the voltage of the positive temperature coefficient voltage input terminal or the temperature detection voltage input terminal is applicable to the present invention, and is not limited to this embodiment.

[0089] like Figure 4As shown, the over-temperature detection module 21 also includes a second trimming unit 215, which is connected to the output end of the operational amplifier unit 211 to trim the output current of the over-temperature detection module 211 (i.e., trim the output slope of the current signal Itsc), so that the output current of the over-temperature detection module 21 falls within a preset current range, thereby ensuring high consistency of the over-temperature shutdown point TSD; the preset current range can be set according to actual needs. As an example, the structure of the second trimming unit is the same as that of the first trimming unit, and will not be repeated here.

[0090] like Figure 5 and Figure 6 As shown, the test method of the over-temperature detection module 21 is as follows:

[0091] S1) providing at least two chips, each of which is provided with an over-temperature detection module 21 of the present invention.

[0092] S2) Switch the mode of the over-temperature detection module 21 from the normal working mode to the test mode; wherein, in the normal working mode, the mode switching unit 212 configures the positive temperature coefficient voltage VPTAT to be connected to the non-inverting input terminal of the operational amplifier unit 211, and configures the temperature detection voltage VBE to be connected to the inverting input terminal of the operational amplifier unit 211; in the test mode, the mode switching unit 212 configures the temperature detection voltage VBE to be connected to the non-inverting input terminal of the operational amplifier unit 211, and configures the positive temperature coefficient voltage VPTAT to be connected to the inverting input terminal of the operational amplifier unit 211.

[0093] Specifically, in the normal working mode, the mode control signal / test is at a high level, and the mode control signal test is at a low level. At this time, the first switch SW1, the third switch SW3, and the fifth switch SW5 are turned on, and the second switch SW2, the fourth switch SW4, and the sixth switch SW6 are turned off. Figure 5 As shown. When the positive temperature coefficient voltage VPTAT is greater than the temperature detection voltage VBE, the current signal Itsc is output, and the leakage current I7 of the tenth PMOS tube MP10 and the third NMOS tube MN3 is equal to the positive and negative input voltage difference VPTAT-VBE of the operational amplifier unit 211 divided by the resistance value Rslope of the first or second resistor. The current I7 and the resistance value Rslope are inversely related, and are linearly proportional to the voltage difference VPTAT-VBE, satisfying the following relationship:

[0094]

[0095] Then, the output current signal Itsc satisfies the following relationship:

[0096]

[0097] The current I7 and the current signal Itsc will affect the output current of the control loop, reducing the output current, thereby achieving the function of reducing power consumption during over-temperature.

[0098] Specifically, in the test mode, the mode control signal / test is at a low level, and the mode control signal test is at a high level. At this time, the first switch SW1, the third switch SW3, and the fifth switch SW5 are turned off, and the second switch SW2, the fourth switch SW4, and the sixth switch SW6 are turned on. Figure 6 As shown. Since the positive temperature coefficient voltage VPTAT is less than the temperature detection voltage VBE at room temperature, the input signal (polarity) of the operational amplifier unit 211 is swapped, thereby obtaining the current I7 that satisfies the following relationship:

[0099]

[0100] Then, the mirror image of the current I7 is realized through the ninth NMOS tube MN9, the fifth PMOS tube MP5 and the sixth PMOS tube MP6, and then the output voltage VDELTA=I7*Rslope=VBE-VPTAT is generated through a fifth resistor R5 (the resistance value is Rslope, which is the same as the first resistor and the second resistor). In this way, only one test pin is needed to read the voltage difference VDELTA between VBE and VPTAT, and two test pins are not needed to read the voltage values ​​of VBE and VPTAT respectively and then make the difference; it is not only beneficial to the layout, but also can reduce the workload of peripheral testing.

[0101] It should be noted that, in this example, the output voltage VDELTA=VBE-VPTAT. In actual use, the output voltage VDELTA and VBE-VPTAT may be in a proportional relationship, which is not limited to this embodiment.

[0102] S3) At room temperature, based on the output signal of the voltage difference output unit 213, the voltage difference VBE-VPTAT between the temperature detection voltage and the positive temperature coefficient voltage is obtained; if the voltage difference does not fall within the preset voltage difference range, the corresponding positive temperature coefficient voltage input terminal or the temperature detection voltage input terminal is adjusted until the voltage difference of the two input terminals of each operational amplifier unit falls within the preset voltage difference range, thereby making the over-temperature drop current starting inflection point of each chip consistent. Among them, the normal temperature is generally 25°C. In this example, the normal temperature is set to 0°C to 30°C, including but not limited to 5°C, 10°C, 15°C, 20°C, 28°C, which are not listed here one by one.

[0103] Specifically, when a single chip is trimmed, 1) the output voltage VDELTA of the voltage difference output unit 213 is first measured to obtain the voltage difference ΔV=VBE-VPTAT between the temperature detection voltage and the positive temperature coefficient voltage.

[0104] 2) adjusting the positive temperature coefficient voltage VPTAT or the temperature detection voltage VBE according to the voltage difference ΔV; more specifically, calculating the difference between the actual voltage difference and the middle value of the preset voltage difference range, and adjusting the input voltage in units of minimum step size according to the difference. As an example, it is set to 4-bit trimming, and the ratio of the trimming resistors is set to 1:2:4:8. If the corresponding ratio of the minimum trimming resistor is set to ±1.5%, the starting inflection point of the over-temperature reduction current can be achieved within a very small range of change, for example, within ±3%; as shown in the following table, step is the minimum step size, and in the initial state, fuse4, fuse3, fuse2, and fuse1 are 0, 0, 0, 0 respectively; when the measured actual voltage difference is near the center value + 1step value, fuse4, fuse3, fuse2, and fuse1 are set to 0, 0, 0, 1, then fuse1 is blown, so that the voltage difference after it is blown is near the center value, and so on. When the measured actual voltage difference is within the required center value ±0.5step (that is, the preset voltage difference range of this embodiment), no trimming is required.

[0105]

[0106]

[0107] 3) After adjustment, the output voltage of the voltage difference output unit 213 is measured again, and the voltage difference range is continuously tightened until the voltage difference falls within the preset voltage difference range.

[0108] The above-mentioned measurement is performed on the output voltage of the voltage difference output unit 213 in each chip. If the voltage difference does not fall within the preset voltage difference range, adjustment is performed so that the voltage difference at the two input ends of the over-temperature detection module 11 in each chip falls within the preset voltage difference range, thereby making the over-current voltage reduction starting point of each chip consistent.

[0109] As another implementation of the present invention, the over-temperature detection test method also includes: detecting the output current of the operational amplifier unit in each chip, and if the output current does not fall within the preset current range, adjusting the output current until the output current of each operational amplifier unit falls within the preset current range, thereby making the over-temperature shutdown point of each chip consistent.

[0110] Embodiment 2

[0111] like Figure 7As shown, this embodiment provides an over-temperature detection module 21 , which is different from the first embodiment in the structure of the mode switching unit 212 and the connection relationship with the operational amplifier unit 211 .

[0112] Specifically, the operational amplifier unit 211 includes a second bias circuit 211b, a third resistor R3, a fourth resistor R4, a third PMOS transistor MP3, a fourth PMOS transistor MP4, a fifth NMOS transistor MN5, a sixth NMOS transistor MN6, a seventh NMOS transistor MN7 and an eighth NMOS transistor MN8. The second bias circuit 211b provides a fourth bias current I4, a fifth bias current I5 and a sixth bias current I6; in this example, the structure of the second bias circuit 211b is the same as that of the first bias circuit 211a. The first ends of the third resistor R3 and the fourth resistor R4 are connected to the fourth bias current I4. The second end of the third resistor R3 is connected to the ground via the third PMOS transistor MP3 and the fifth NMOS transistor MN5 in turn. The second end of the fourth resistor R4 is connected to the ground via the fourth PMOS transistor MP4 and the sixth NMOS transistor MN6 in turn. The gate of the fifth NMOS transistor MN5 is connected to the drain, and is connected to the gate of the sixth NMOS transistor MN6. The fifth bias current I5 is loaded on the second end of the third resistor R3, and the sixth bias current I6 is loaded on the second end of the fourth resistor R4. The drain of the seventh NMOS tube MN7 is connected to the sixth bias current I6, the gate is connected to the drain of the fourth PMOS tube MP4, and the source is grounded. The gate of the eighth NMOS tube MN8 is connected to the gate of the seventh NMOS tube MN7, the source is grounded, and the drain outputs the current signal Itsc. In this example, the resistance values ​​of the third resistor R3, the fourth resistor R4 and the fifth resistor R5 are the same, the width-to-length ratio of the fifth NMOS tube MN5 to the sixth NMOS tube MN6 is 1:1, and the width-to-length ratio of the seventh NMOS tube MN7 to the eighth NMOS tube MN8 is m:n.

[0113] It should be noted that any circuit structure that can generate a current signal Itsc that changes linearly with the difference between the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT (i.e., VBE-VPTAT) when the temperature detection voltage VBE is less than the positive temperature coefficient voltage VPTAT is applicable to the present invention and will not be described in detail here.

[0114] Specifically, the mode switching unit 212 includes a seventh switch SW7, an eighth switch SW8, a ninth switch SW9, and a tenth switch SW10. The positive temperature coefficient voltage VPTAT is connected to the gates of the third PMOS transistor MP3 and the fourth PMOS transistor MP4 via the seventh switch SW7 and the eighth switch SW8, respectively, and the temperature detection voltage VBE is connected to the gates of the third PMOS transistor MP3 and the fourth PMOS transistor MP4 via the ninth switch SW9 and the tenth switch SW10, respectively.

[0115] Specifically, in the normal working mode, the mode control signal / test is at a high level, and the mode control signal test is at a low level. At this time, the seventh switch SW7 and the tenth switch SW10 are turned on, and the eighth switch SW8 and the ninth switch SW9 are turned off. For the circuit structure, see Figure 5 In the test mode, the mode control signal / test is at a low level, and the mode control signal test is at a high level. At this time, the seventh switch SW7 and the tenth switch SW10 are turned off, and the eighth switch SW8 and the ninth switch SW9 are turned on. For the circuit structure, see Figure 6 .

[0116] It should be noted that other circuit structures (including but not limited to the first adjustment unit and the second adjustment unit) and working principles of the over-temperature detection module 21 of this embodiment are the same as those of the first embodiment, and are not described in detail here.

[0117] Embodiment 3

[0118] like Figure 8 As shown, this embodiment provides a constant current control circuit 2, and the constant current control circuit 2 includes:

[0119] The over-temperature detection module 21 and the operational amplifier module 22;

[0120] like Figure 8 As shown, the first input terminal of the operational amplifier module 22 receives the current sampling signal CS via the series resistor R6, the second input terminal receives the reference signal VREF, and outputs the switch control signal. As an example, the first input terminal of the operational amplifier module 22 is set as the inverting input terminal, and the second input terminal is set as the non-inverting input terminal. In actual use, the relationship between the input signal and the polarity of the corresponding input terminal can be adjusted as needed, and the logic can be adjusted through the inverter, which is not limited to this embodiment.

[0121] like Figure 8 As shown, the over-temperature detection module 21 is connected to the first input terminal of the operational amplifier module 22, and generates a linearly changing current signal Itsc when it is detected that the temperature exceeds a preset value.

[0122] Specifically, the circuit structure of the over-temperature detection module 21 is shown in Embodiment 1 or Embodiment 2, which will not be described in detail here. The over-temperature detection module 21 provides a current Itsc to the first input terminal of the operational amplifier module 22 when the temperature is over, so as to adjust the switch control signal output by the operational amplifier module 22, and then realize the over-temperature current reduction function by adjusting the power switch.

[0123] like Figure 8 As shown, this embodiment also provides a constant current control system, and the constant current control system includes:

[0124] The power switch tube Q1, the sampling circuit 3 and the constant current control circuit 2 of this embodiment.

[0125] like Figure 8 As shown, the drain of the power switch tube Q1 is connected to a load (including but not limited to an LED), and the source is grounded via the sampling circuit 3. In this embodiment, the sampling circuit 3 is implemented by a sampling resistor Rcs.

[0126] like Figure 8 As shown, the input end of the constant current control circuit 2 is connected to the output end of the sampling circuit 3, and the output end is connected to the gate of the power switch tube Q1.

[0127] Specifically, when it is detected that the temperature does not exceed the preset value, the constant current control circuit 2 controls the power switch tube Q1 based on the difference between the sampling signal CS output by the sampling circuit 3 and the reference signal VREF to achieve constant current output. When it is detected that the temperature exceeds the preset value, the current Itsc is superimposed on the sampling signal CS output by the sampling circuit 3, and then the power switch tube Q1 is controlled based on the difference between the superimposed signal and the reference signal VREF to linearly reduce the output current and achieve over-temperature current reduction. Since the output current of the over-temperature detection module 21 of the present invention changes linearly, the output current of the constant current control system also changes linearly during the over-temperature current reduction process, which can improve customer experience for applications such as LEDs.

[0128] The constant current control system of this embodiment is a linear constant current control loop. When the power switch tube Q1 is turned on, a voltage drop VCS will be generated on the sampling resistor Rcs, and the operational amplifier module 22 generates a switch control signal of the power switch tube Q1. The over-temperature detection module 21 generates a current Itsc on the series resistor R6, and the potential VINN of the first input terminal of the operational amplifier module 22 is VCS+Itsc*R6 through the series resistor R6. After the loop adjustment, VREF=VINN is finally achieved, and the output current of the power switch tube Q1 is changed by changing the gate voltage of the power switch tube Q1. When the temperature gradually increases, the output current Itsc of the over-temperature detection module 21 also gradually increases, and the voltage VCS on the sampling input terminal CS gradually decreases. When the current Itsc reaches a certain value (corresponding to the current of the over-temperature shutdown point), VREF=Itsc*R6, and VCS tends to zero at this time.

[0129] Embodiment 4

[0130] like Fig. 9 As shown, this embodiment provides a constant current control circuit 2 and a constant current control system, which is different from the third embodiment in that the over-temperature detection module 21 is connected to the second input end of the operational amplifier module 22, that is, the same input end as the reference signal VREF.

[0131] Specifically, the first input of the operational amplifier module 22 receives the current sampling signal CS, the second input terminal receives the reference signal VREF, and outputs the switch control signal. The reference signal VREF is obtained by the third positive temperature coefficient current IPTAT3 acting on the resistor R7. The overtemperature detection module 21 is connected to the second input terminal of the operational amplifier module 22, and the current Itsc is superimposed on the reference signal VREF. When the temperature gradually rises, the current Itsc gradually increases, and the reference signal VREF decreases with the increase of temperature. The reference signal VREF = (IPTAT3-Itsc)*R7. When the reference signal VREF gradually drops to zero, the voltage VCS on the sampling input terminal CS also drops to zero.

[0132] Embodiment 5

[0133] This embodiment provides a constant current control circuit 2 and a constant current control system, which are different from the third and fourth embodiments in that the operational amplifier module 22 in the third and fourth embodiments is replaced by a comparison module 23; and further includes a pulse width modulation module 24, which is connected to the output end of the comparison module 23 and adjusts the pulse width based on the comparison result to obtain a switch control signal. Fig.10The over-temperature detection module is set at one end of the comparison module receiving the current sampling signal, and the over-temperature detection module is set at one end of the comparison module receiving the reference signal. Fig. 9 ; The flow control system of this embodiment is a switch PWM constant current control loop; the specific structure and working principle are not described here one by one.

[0134] In summary, the present invention provides an over-temperature detection module, a constant current control circuit and a test method for an over-temperature detection module, wherein the over-temperature detection module comprises: an operational amplifier unit, a mode switching unit, a voltage difference output unit and a first trimming unit; the input end of the operational amplifier unit receives a positive temperature coefficient voltage and a temperature detection voltage respectively, and when the temperature detection voltage is less than the positive temperature coefficient voltage, a current signal that changes linearly with the difference between the temperature detection voltage and the positive temperature coefficient voltage is generated; the mode switching unit is connected to the operational amplifier unit, and the corresponding relationship between the input signal and the output signal of the operational amplifier unit is interchanged to realize the interchange between a normal working mode and a test mode; the voltage difference output unit is connected between the output end of the operational amplifier unit and a test pin, and the voltage difference between the temperature detection voltage and the positive temperature coefficient voltage is generated and output based on the output signal of the operational amplifier unit; the first trimming unit acts on the input end of the positive temperature coefficient voltage or the temperature detection voltage, and trims the input end voltage so that the voltage difference between the two input ends of the operational amplifier unit falls within a preset voltage difference range. The over-temperature detection module of the present invention can directly obtain the voltage difference of the input signal through the test mode with only one test pin, thereby reducing the test pins and test steps and simplifying the peripheral program; the input and output change linearly, and can be used for the over-temperature current reduction circuit, and the high consistency of the over-temperature current reduction starting point can be achieved through the adjustment circuit; the output current of the operational amplifier unit is additionally adjusted to further ensure the consistency of the over-temperature shutdown point; the present invention is applicable to the constant current control system, and the constant current control system can be a linear constant current or a switch-type PWM constant current. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0135] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An over-temperature detection module, characterized in that: The over-temperature detection module at least includes: An operational amplifier unit, a mode switching unit, a pressure difference output unit and a first trimming unit; The input end of the operational amplifier unit receives a positive temperature coefficient voltage and a temperature detection voltage respectively, and when the temperature detection voltage is less than the positive temperature coefficient voltage, generates a current signal that changes linearly with the difference between the temperature detection voltage and the positive temperature coefficient voltage; The mode switching unit is connected to the operational amplifier unit, and exchanges the corresponding relationship between the input signal and the output signal of the operational amplifier unit to achieve the exchange between the normal working mode and the test mode; The voltage difference output unit is connected between the output end of the operational amplifier unit and the test pin, and generates and outputs the voltage difference between the temperature detection voltage and the positive temperature coefficient voltage based on the output signal of the operational amplifier unit; The first trimming unit acts on the input end of the positive temperature coefficient voltage or the temperature detection voltage to trim the input end voltage so that the voltage difference between the two input ends of the operational amplifier unit falls within a preset voltage difference range.

2. The over-temperature detection module according to claim 1, characterized in that: The operational amplifier unit includes a first bias circuit, a first resistor, a second resistor, a first PMOS transistor, a second PMOS transistor, a first NMOS transistor, a second NMOS transistor, a third NMOS transistor and a fourth NMOS transistor, and the mode switching unit includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch and a sixth switch; The first bias circuit provides a first bias current, a second bias current and a third bias current; the first ends of the first resistor and the second resistor are connected to the first bias current; the second end of the first resistor is grounded via the first PMOS tube and the first NMOS tube in sequence; the second end of the second resistor is grounded via the second PMOS tube and the second NMOS tube in sequence; the first NMOS tube is connected to the gate of the second NMOS tube; the first switch is connected between the drain and the gate of the first NMOS tube, and the second switch is connected between the drain and the gate of the second NMOS tube; the positive temperature coefficient voltage is connected to the first PMOS tube The temperature detection voltage is connected to the gate of the second PMOS tube; the second bias current is loaded on the second end of the first resistor; the third bias current is loaded on the second end of the second resistor via the third switch, and is loaded on the second end of the first resistor via the fourth switch; the drain of the third NMOS tube is connected to the third bias current, and the source is grounded; the gate of the third NMOS tube is connected to the drain of the second PMOS tube via the fifth switch, and is connected to the drain of the first PMOS tube via the sixth switch; the gate of the fourth NMOS tube is connected to the gate of the third NMOS tube, the source is grounded, and the drain outputs the current signal.

3. The over-temperature detection module according to claim 1, characterized in that: The operational amplifier unit includes a second bias circuit, a third resistor, a fourth resistor, a third PMOS tube, a fourth PMOS tube, a fifth NMOS tube, a sixth NMOS tube, a seventh NMOS tube and an eighth NMOS tube; The second bias circuit provides a fourth bias current, a fifth bias current and a sixth bias current; the first ends of the third resistor and the fourth resistor are connected to the fourth bias current; the second end of the third resistor is grounded via the third PMOS tube and the fifth NMOS tube in sequence; the second end of the fourth resistor is grounded via the fourth PMOS tube and the sixth NMOS tube in sequence; the gate and drain of the fifth NMOS tube are connected, and are also connected to the gate of the sixth NMOS tube; the fifth bias current is loaded on the second end of the third resistor, and the sixth bias current is loaded on the second end of the fourth resistor; the drain of the seventh NMOS tube is connected to the sixth bias current, the gate is connected to the drain of the fourth PMOS tube, and the source is grounded; the gate of the eighth NMOS tube is connected to the gate of the seventh NMOS tube, the source is grounded, and the drain outputs the current signal.

4. The over-temperature detection module according to claim 3, characterized in that: The mode switching unit includes a seventh switch, an eighth switch, a ninth switch and a tenth switch; the positive temperature coefficient voltage is connected to the gates of the third PMOS tube and the fourth PMOS tube via the seventh switch and the eighth switch, respectively, and the temperature detection voltage is connected to the gates of the third PMOS tube and the fourth PMOS tube via the ninth switch and the tenth switch, respectively.

5. The over-temperature detection module according to any one of claims 1 to 4, characterized in that: The voltage difference output unit includes a ninth NMOS tube, a fifth PMOS tube, a sixth PMOS tube and a fifth resistor; the source of the ninth NMOS tube is grounded, the gate is connected to the output end of the operational amplifier unit, and the drain is connected to the drain of the fifth PMOS tube; the gate and drain of the fifth PMOS tube are connected, and the source is connected to the power supply; the source of the sixth PMOS tube is connected to the power supply, the gate is connected to the gate of the fifth PMOS tube, and the drain is connected to the test pin and grounded via the fifth resistor.

6. The over-temperature detection module according to any one of claims 1 to 4, characterized in that: The over-temperature detection module further includes a second trimming unit, which is connected to the output end of the operational amplifier unit and trims the output current of the over-temperature detection module so that the output current of the over-temperature detection module falls within a preset current range.

7. A constant current control circuit, characterized in that: The constant current control circuit at least comprises: An operational amplifier module and an over-temperature detection module as claimed in any one of claims 1 to 6; The operational amplifier module receives a current sampling signal at a first input terminal, receives a reference signal at a second input terminal, and outputs a switch control signal; The over-temperature detection module is connected to the first input terminal or the second input terminal of the operational amplifier module, and generates a linearly changing current signal when it is detected that the temperature exceeds a preset value; Wherein, when the over-temperature detection module is connected to the first input terminal of the operational amplifier module, a resistor is further connected in series between the first input terminal of the operational amplifier module and the current sampling signal.

8. A constant current control circuit, characterized in that: The constant current control circuit at least comprises: A comparison module, a pulse width modulation module and an over-temperature detection module as claimed in any one of claims 1 to 6; The first input terminal of the comparison module receives a current sampling signal, the second input terminal receives a reference signal, and outputs a comparison result; The pulse width modulation module is connected to the output end of the comparison module, and adjusts the pulse width based on the comparison result to obtain a switch control signal; The over-temperature detection module is connected to the first input terminal or the second input terminal of the comparison module, and generates a linearly changing current signal when it is detected that the temperature exceeds a preset value; Wherein, when the over-temperature detection module is connected to the first input terminal of the comparison module, a resistor is further connected in series between the first input terminal of the comparison module and the current sampling signal.

9. A constant current control system, characterized in that: The constant current control system at least comprises: A power switch tube, a sampling circuit and a constant current control circuit as claimed in claim 7 or 8; The drain of the power switch tube is connected to the load, and the source is grounded via the sampling circuit; The input end of the constant current control circuit is connected to the output end of the sampling circuit, and the output end is connected to the gate of the power switch tube.

10. A method for testing an over-temperature detection module, characterized in that: The testing method of the over-temperature detection module includes: Providing at least two chips, each chip being provided with an over-temperature detection module as described in any one of claims 1 to 6; Switching the mode of the over-temperature detection module from the normal working mode to the test mode; wherein, in the normal working mode, the mode switching unit configures the positive temperature coefficient voltage to be connected to the non-inverting input terminal of the operational amplifier unit, and configures the temperature detection voltage to be connected to the inverting input terminal of the operational amplifier unit; in the test mode, the mode switching unit configures the temperature detection voltage to be connected to the non-inverting input terminal of the operational amplifier unit, and configures the positive temperature coefficient voltage to be connected to the inverting input terminal of the operational amplifier unit; At normal temperature, the voltage difference between the temperature detection voltage and the positive temperature coefficient voltage is obtained based on the output signal of the voltage difference output unit; if the voltage difference does not fall within the preset voltage difference range, the corresponding positive temperature coefficient voltage input terminal or the temperature detection voltage input terminal is adjusted until the voltage difference between the two input terminals of each operational amplifier unit falls within the preset voltage difference range, thereby making the starting inflection point of the over-temperature drop current of each chip consistent.

11. The method for testing the over-temperature detection module according to claim 10, characterized in that: The testing method of the over-temperature detection module also includes: detecting the output current of the operational amplifier unit in each chip, and if the output current does not fall within the preset current range, adjusting the output current until the output current of each operational amplifier unit falls within the preset current range, thereby keeping the over-temperature shutdown point of each chip consistent.

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