Constant current control circuit and system, over-temperature detection module and trimming method

Abstract

The invention provides a constant current control circuit and system, an over-temperature detection module and a trimming method, and the circuit comprises an operational amplification unit which amplifies and outputs the difference value 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 output current linear adjusting unit generates a current signal which linearly changes along with the difference value of the temperature detection voltage and the positive temperature coefficient voltage; and the first trimming unit is used for trimming the input end of the positive temperature coefficient voltage or the temperature detection voltage, so that the voltage difference falls into a preset voltage difference range. According to the invention, the high consistency of the starting point of the over-temperature current drop can be realized, the consistency of the over-temperature turn-off point can be ensured, and the circuit is suitable for a constant-current control system, simple in structure and low in research and development cost.

Description

Technical Field

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

[0002] The starting inflection point of the over-temperature current reduction circuit is an important parameter of the chip's electrical characteristics. The over-temperature detection circuit is often implemented using a transconductance amplifier architecture, such as Figure 1 As shown, the input end of the transconductance amplifier receives the positive temperature coefficient voltage VPTAT and the temperature detection voltage VBE respectively. Transistors M1 and M2 provide bias current I5 for the input pair tubes M3 and M4 through the mirror bias current IB. I5=I1+I2. I1 and I2 are the currents flowing through the input pair tubes M3 and M4 respectively. The current I4 flowing through the transistor M6 is equal to I2. The width-to-length ratio of transistors M6 and M7 is the same, so the current I6 flowing through transistor M7 is also equal to I2. The current I2 gradually increases as the temperature detection voltage VBE decreases; assuming that the transconductance gain of the transconductance amplifier is Gm, the current I2 satisfies: I2=Gm*(VPTAT-VBE); and because the current ratio relationship between transistors M8 and M9 is 1:n, the final over-temperature detection current Itsc=n*Gm*(VPTAT-VBE). As shown Figure 2 As shown, the over-temperature detection current Itsc is a curve that changes nonlinearly with the voltage difference between the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT, wherein the temperature point corresponding to 1% to 2% of the full current of the over-temperature detection current Itsc is set as the over-temperature current reduction starting inflection point TSC, and when Itsc increases to the maximum (i.e., the full current is 100%), the temperature point at which the voltage of the external current sampling signal VCS becomes zero is the over-temperature shutdown point TSD.

[0003] Since the over-temperature detection circuit generally sets the starting inflection point of the current reduction to a high temperature, for example, 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, and 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. Therefore, providing an over-temperature current reduction circuit that can achieve higher accuracy and better consistency has become one of the 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 a constant current control circuit, system, over-temperature detection module and adjustment method, which are used to solve the problems of nonlinear change of output current of the over-temperature detection circuit in the prior art, poor accuracy and consistency of the starting inflection point of over-temperature reduction current, etc.

[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, an output current linear adjustment 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 amplifies and outputs a difference between the temperature detection voltage and the positive temperature coefficient voltage;

[0009] The output current linear adjustment unit is connected to the output end of the operational amplifier unit, and generates a current signal that changes linearly with the difference between the temperature detection voltage and the positive temperature coefficient voltage when the temperature detection voltage is less than the positive temperature coefficient voltage;

[0010] 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.

[0011] Optionally, the output current linear adjustment unit includes a first PMOS tube, a second PMOS tube, a first NMOS tube and a second NMOS tube;

[0012] The first PMOS tube, the second PMOS tube and the first NMOS tube are connected in series between a power supply and a ground in sequence, the gate of the first PMOS tube receives a bias voltage, the gate of the second PMOS tube receives the temperature detection voltage, the gate of the first NMOS tube is connected to the output end of the operational amplifier unit; the source of the second NMOS tube is connected to the drain of the second PMOS tube, the gate is connected to the source of the second PMOS tube, and the drain outputs the current signal.

[0013] More optionally, when the temperature detection voltage is less than or equal to the positive temperature coefficient voltage, the current flowing through the first PMOS tube is half of the sum of the currents flowing through the input pair tubes of the operational amplifier unit.

[0014] Optionally, the over-temperature detection module further includes an output unit; the output unit is connected to an output end of the output current linear adjustment unit to proportionally amplify the current output by the output current linear adjustment unit.

[0015] More optionally, the over-temperature detection module further includes a second trimming unit, which is connected to the output end of the output 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.

[0016] More optionally, the first trimming unit includes a trimming control unit, N trimming resistors and N switches, where N is a natural number greater than or equal to 2; the N trimming resistors are connected in series in sequence; the N switches correspond to the N trimming resistors one by one and are respectively connected in parallel to the two ends of the corresponding trimming resistors; the trimming control unit is used to generate a control signal for the switch;

[0017] When the first trimming unit is set at the input end of the positive temperature coefficient voltage, each trimming resistor is set between the input end of the positive temperature coefficient voltage and the ground, and is connected in series with the voltage divider resistor at the input end of the positive temperature coefficient voltage; when the first trimming unit is set at the input end of the temperature detection voltage, each trimming resistor is set between the input end of the temperature detection voltage and the temperature detection device.

[0018] More optionally, the resistance values ​​of the trimming resistors increase in sequence by 2 times.

[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 operational amplifier module has a first input terminal receiving a current sampling signal, a second input terminal receiving a reference signal, and an output terminal outputting a switch control signal;

[0022] 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 current signal that changes linearly with the increase of temperature when it is detected that the temperature is greater than or equal to a preset value;

[0023] 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.

[0024] 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:

[0025] Comparison module and the above-mentioned over-temperature detection module;

[0026] 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;

[0027] 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;

[0028] 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.

[0029] In order to achieve the above-mentioned object and other related objects, the present invention also provides a constant current control system, which at least includes:

[0030] Power switch tube, sampling circuit and the above constant current control circuit;

[0031] The drain of the power switch tube is connected to the load, and the source is grounded via the sampling circuit;

[0032] 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.

[0033] In order to achieve the above-mentioned object and other related objects, the present invention further provides an over-temperature detection adjustment method, the over-temperature detection adjustment method comprising:

[0034] Providing at least two chips, each of which is provided with the above-mentioned over-temperature detection module;

[0035] At room temperature, the voltage of the positive temperature coefficient voltage input terminal and the voltage of the temperature detection voltage input terminal on each chip are tested respectively, and the voltage difference between the two input terminals is calculated; 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, so that the starting inflection point of the over-temperature drop current of each chip remains consistent.

[0036] Optionally, the method for trimming the corresponding positive temperature coefficient voltage input terminal or the temperature detection voltage input terminal includes: calculating the difference between the actual voltage difference and the middle value of the preset voltage difference range, and adjusting the input terminal voltage in units of minimum step size according to the difference.

[0037] More optionally, the over-temperature detection adjustment method also includes: detecting the output current of the over-temperature detection module 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 over-temperature detection module falls within the preset current range, so that the over-temperature shutdown point of each chip remains consistent.

[0038] As described above, the constant current control circuit, system, over-temperature detection module and adjustment method of the present invention have the following beneficial effects:

[0039] 1. 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] 2. The present invention also adds an additional adjustment to the output current of the transconductance amplifier to further ensure the consistency of the over-temperature shutdown point.

[0041] 3. 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.

[0042] 4. The present invention adds a small amount of transistors on the existing basis, has a simple structure and low R&D cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the structure of a transconductance amplifier in the prior art.

[0044] Figure 2 Display as Figure 1 Schematic diagram of the key node waveforms of the transconductance amplifier.

[0045] Figure 3 Shown is a structural schematic diagram of the over-temperature detection module of the present invention.

[0046] Figure 4 Shown is a schematic diagram of waveforms of key nodes of the over-temperature detection module of the present invention.

[0047] Figure 5 Shown is a distribution diagram of the starting inflection point of the over-temperature drop current.

[0048] Figure 6 It is a schematic structural diagram showing the first trimming unit of the present invention being disposed at the positive temperature coefficient voltage input terminal.

[0049] Figure 7 It is a schematic structural diagram showing that the first trimming unit of the present invention is disposed at the temperature detection voltage input terminal.

[0050] Figure 8 Shown is another structural schematic diagram of the over-temperature detection module of the present invention.

[0051] Fig. 9 It is a schematic flow chart of the over-temperature detection and adjustment method of the present invention.

[0052] Fig.10 Shown is a structural schematic diagram of a constant current control circuit and a constant current control system of the present invention.

[0053] Fig.11 Shown is a structural schematic diagram of another constant current control circuit and constant current control system of the present invention.

[0054] Fig.12 Shown is a structural schematic diagram of another constant current control circuit and constant current control system of the present invention.

[0055] Component number description

[0056] 1 Constant current control circuit

[0057] 11 Over temperature detection module

[0058] 111 Operational amplifier unit

[0059] 112 Output current linear regulation unit

[0060] 113 Output unit

[0061] 114 First Adjustment Unit

[0062] 114a Trim control unit

[0063] 115 Second Adjustment Unit

[0064] 12 Operational amplifier module

[0065] 13 Comparison Module

[0066] 14 Pulse Width Modulation Module

[0067] 2 Sampling Circuit DETAILED DESCRIPTION

[0068] 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.

[0069] See also Figure 3 to Figure 12It 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.

[0070] Embodiment 1

[0071] like Figure 3 As shown, this embodiment provides an over-temperature detection module 11 with a linearly changing output, including: an operational amplifier unit 111 and an output current linear adjustment unit 112 .

[0072] like Figure 3 As shown, the input end of the operational amplifier unit 111 receives the positive temperature coefficient voltage VPTAT and the temperature detection voltage VBE respectively, and amplifies the difference between the positive temperature coefficient voltage VPTAT and the temperature detection voltage VBE and outputs it.

[0073] Specifically, in this embodiment, the operational amplifier unit 111 includes a third PMOS tube MP3, a fourth PMOS tube MP4, a fifth PMOS tube MP5, a sixth PMOS tube MP6, a third NMOS tube MN3 and a fourth NMOS tube MN4; the third PMOS tube MP3 and the fourth PMOS tube MP4 form a current mirror structure, and the bias current IB is scaled and mirrored to the drain of the fourth PMOS tube MP4; the fifth PMOS tube MP5 and the sixth PMOS tube MP6 form an input pair tube, and the fifth PMOS tube MP 5 and the source of the sixth PMOS tube MP6 are connected to the drain of the fourth PMOS tube MP4; the gate of the fifth PMOS tube MP5 receives the positive temperature coefficient voltage VPTAT, and the drain is connected to the drain and gate of the third NMOS tube MN3; the source of the third NMOS tube MN3 is grounded; the gate of the sixth PMOS tube MP6 receives the temperature detection voltage VBE, and the drain is connected to the drain and gate of the fourth NMOS tube MN4 and serves as the output end of the operational amplifier unit 111; the source of the fourth NMOS tube MN4 is grounded.

[0074] It should be noted that, in this example, the positive temperature coefficient voltage VPTAT is obtained by the positive temperature coefficient current acting on the voltage divider resistor. In actual use, any circuit structure that can generate a positive temperature coefficient voltage is applicable, and it is not described in detail here. In this example, the temperature detection voltage VBE is the base and emitter voltage difference of a bipolar transistor (PNP or NPN). In actual use, any circuit structure that can reflect temperature information based on the voltage across the PN junction is applicable, and it is not described in detail here. Any circuit structure that can obtain the difference between the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT is applicable to the present invention, and is not limited to this embodiment.

[0075] like Figure 3 As shown, the output current linear adjustment unit 112 is connected to the output end of the operational amplifier unit 111, 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.

[0076] Specifically, in this embodiment, when the temperature detection voltage VBE is greater than the positive temperature coefficient voltage VPTAT, the output current of the output current linear adjustment unit 112 is 0. When the temperature detection voltage VBE is equal to the positive temperature coefficient voltage VPTAT, the output current linear adjustment unit 112 starts to output current; and as the difference between the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT increases, the current output by the output current linear adjustment unit 112 increases linearly. Any circuit structure that can achieve the above functions is applicable to the present invention.

[0077] More specifically, in this example, the output current linear adjustment unit 112 includes a first PMOS transistor MP1, a second PMOS transistor MP2, a first NMOS transistor MN1, and a second NMOS transistor MN2. The first PMOS transistor MP1, the second PMOS transistor MP2 and the first NMOS transistor MN1 are sequentially connected in series between the power supply VDD and the ground (i.e., the source of the first PMOS transistor MP1 is connected to the power supply, and the drain is connected to the source of the second PMOS transistor MP2; the drain of the second PMOS transistor MP2 is connected to the drain of the first NMOS transistor MN1; the source of the first NMOS transistor MN1 is grounded), the gate of the first PMOS transistor MP1 receives a bias voltage (in this example, the first PMOS transistor MP1 and the third PMOS transistor MP3 form a current mirror structure, and the bias voltage is provided by the third PMOS transistor MP3), the gate of the second PMOS transistor MP2 receives the temperature detection voltage VBE, the gate of the first NMOS transistor MN1 is connected to the output end of the operational amplifier unit 111; the source of the second NMOS transistor MN2 is connected to the drain of the second PMOS transistor MP2, the gate is connected to the source of the second PMOS transistor MP2, and the drain outputs the current signal. Furthermore, in this example, when the temperature detection voltage VBE is less than or equal to the positive temperature coefficient voltage VPTAT, the current flowing through the first PMOS tube MP1 is half of the sum of the currents flowing through the input pair of tubes of the operational amplifier unit 111, that is, the ratio of the width-to-length ratio of the fourth PMOS tube MP4 to the first PMOS tube MP1 is 2:1. The ratio can be set as needed in actual use.

[0078] like Figure 3 As shown, as another implementation of the present invention, the over-temperature detection module 11 further includes an output unit 113. The output unit 113 is connected to the output end of the output current linear adjustment unit 112, and proportionally amplifies the current Id output by the output current linear adjustment unit 112.

[0079] Specifically, in this embodiment, the output unit 113 includes a seventh PMOS tube MP7 and an eighth PMOS tube MP8. The seventh PMOS tube MP7 and the eighth PMOS tube MP8 form a current mirror structure. In this embodiment, the ratio of the width to length ratio of the seventh PMOS tube MP7 and the eighth PMOS tube MP8 is 1:n. Then, the output current Itsc of the output unit 113 is n*Id, where n is a real number greater than 1.

[0080] It should be noted that, in actual use, the output current of the output unit 113 may also be a pull-down current. In this case, a current mirror composed of a stage of NMOS tube is added, which will not be described in detail here.

[0081] like Figure 3 As shown, due to the effect of the second PMOS tube MP2 and the second NMOS tube MN2, 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. Figure 4 As shown, when the temperature is low or at room temperature, the temperature detection voltage VBE is higher than the positive temperature coefficient voltage VPTAT, and the current almost flows through the fifth PMOS tube MP5, that is, Ib1≈Ia, Ib2≈0; when the temperature gradually rises, the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT are getting closer and closer, and the bias current Ia will divide a part of the current to Ib2, at this time the current Ic is equal to Ib2, and the current Ib2 gradually increases as the temperature detection voltage VBE decreases; when the temperature detection voltage VBE gradually decreases to below the positive temperature coefficient voltage VPTAT, the current Ic has increased to half of the current Ia, and current mirroring is realized. The decrease in the temperature detection voltage VBE makes the second PMOS tube MP2 fully turned on, the drain potential of the second PMOS tube MP2 also becomes lower, and the second NMOS tube MN2 is turned on. As an example, the ratio of the width-to-length ratio of the fourth NMOS tube MN4 to the first NMOS tube MN1 is set to 1:1, and the estimated current Ic satisfies:

[0082] Ic=I MP1 =I MP2 =0.5*Ia,I MN1 =I MN2 +I MP2 =Ib2,I MN2 =I MN1 -I MP2 =Ib2-0.5*Ia

[0083] Among them, I MP1 is the current flowing through the first PMOS tube MP1, I MP2 is the current flowing through the second PMOS tube MP2, I MN2 is the current flowing through the second NMOS transistor MN2, I MN1 is the current flowing through the first NMOS transistor MN1, I MN4 is the current flowing through the fourth NMOS transistor MN4.

[0084] Therefore, I TSC =n*Id=n*I MN2=n*(Ib2-0.5*Ia), it can be seen that the output current Itsc of the output unit 113 is a curve that changes linearly with the voltage difference between the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT, and the intersection of the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT is the starting inflection point TSC of the over-temperature drop current.

[0085] In actual tests, since both input terminals of the operational amplifier unit 111 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 5 As shown; due to the use of linear current reduction, if the voltage difference between the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT at room temperature (e.g. 25°C) is equal, the temperature point when the temperature detection voltage VBE and the positive temperature coefficient voltage VPTAT are equal, that is, the over-temperature current reduction starting inflection point TSC, can be guaranteed to be consistent. Therefore, Figure 3 As shown, in order to improve the consistency of the over-temperature drop current starting inflection point TSC, the present invention also includes a first trimming unit 114, which 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.

[0086] Specifically, Figure 6 and Figure 7 As shown, the first trimming unit 114 includes a trimming control unit 114a, N trimming resistors (R1, R2...) and N switches, where N is a natural number greater than or equal to 2. Each trimming resistor (R1, R2...) is 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 114a is used to generate control signals for each switch. As an example, a fuse is provided inside the trimming control unit 114a, and a corresponding control signal is obtained through the fuse. 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... Among them, each trimming resistor can increase in sequence from low potential to high potential according to the resistance value, or can decrease in sequence from low potential to high potential according to the resistance value. Of course, it can also not change in sequence according to the resistance value, which will not be repeated here. In actual use, each trimming resistor can also be set in parallel. In this case, each switch corresponds to each trimming resistor one by one and is connected in series with the corresponding trimming resistor, which will not be described in detail here. Figure 6As shown, the positive temperature coefficient voltage VPTAT is obtained by the first positive temperature coefficient current IPTAT1 acting on the voltage divider resistor RPTAT; when the first trimming unit 114 is set at the input end of the positive temperature coefficient voltage VPTAT, 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 divider resistor RPTAT at the input end of the positive temperature coefficient voltage (the position is not limited, as long as the series relationship is achieved). Figure 7 As shown, the temperature detection voltage VBE is obtained by the second positive temperature coefficient current IPTAT2 acting on the PN junction of the diode D (for example, a bipolar transistor is used); when the first trimming unit 114 is set at the input end of the temperature detection voltage VBE, 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 trim the voltage at the positive temperature coefficient voltage input end or the temperature detection voltage input end is applicable to the present invention, and is not limited to this embodiment.

[0087] After adding the first trimming unit 114, not only can the input and output be linearly changed, but also a higher consistency of the over-temperature current drop starting inflection point can be achieved. It should be noted that the preset voltage difference range can be set according to device characteristics, manufacturing process and other parameters, which will not be described in detail here.

[0088] like Figure 8 As shown, as another implementation of the present invention, the over-temperature detection module 11 of the present invention further includes a second trimming unit 115, which is connected to the output end of the output unit 113 to trim the output current of the over-temperature detection module 11 (i.e., trim the slope of the over-temperature detection module 11), so that the output current of the over-temperature detection module 11 falls within a preset current range to ensure high consistency of the over-temperature shutdown point TSD; the preset current range can be set according to actual needs. In this example, Figure 6 The second adjustment unit 115 is added on the basis of the scheme, and the structure of the second adjustment unit 115 is the same as that of the first adjustment unit. In actual use, Figure 7 The second adjustment unit 115 is added on the basis of the solution. The second adjustment unit 115 can also adopt other structures that can achieve adjustment, which are not described in detail here.

[0089] like Fig. 9 As shown, the adjustment method of the over-temperature detection circuit of this embodiment is as follows:

[0090] At least two chips are provided, and each chip is provided with the over-temperature detection module 11 of the present invention.

[0091] At room temperature, the voltage of the positive temperature coefficient voltage input terminal and the voltage of the temperature detection voltage input terminal on each chip are tested respectively, and the voltage difference between the two input terminals is calculated; 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, so that the over-temperature reduction current starting inflection point of each chip remains consistent and falls within the set range of the preset starting temperature point. Among them, the normal temperature is generally 25°C. In this example, the normal temperature is set to 0°C~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.

[0092] Specifically, Fig. 9 As shown, when a single chip is trimmed, 1) firstly, the voltage values ​​of the two input terminals of the over-temperature detection module 11 (ie, the two input terminals of the operational amplifier unit 111) are measured, which correspond to the positive temperature coefficient voltage VPTAT and the temperature detection voltage VBE respectively.

[0093] 2) Calculate the voltage difference between the two input terminal voltages. In this example, the voltage difference ΔV=VBE-VPTAT.

[0094] 3) 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.

[0095]

[0096] 4) After the adjustment, the voltage values ​​of the two input terminals of the over-temperature detection module 11 are measured again, and the range of the voltage difference is continuously tightened until the voltage difference falls within the preset voltage difference range.

[0097] The above-mentioned measurement is performed on the voltages of the two input terminals of the over-temperature detection module 11 in each chip. If the voltage difference does not fall within the preset voltage difference range, adjustment is performed so that the voltage difference of the two input terminals of the over-temperature detection module 11 in each chip falls within the preset voltage difference range, so that the over-current voltage reduction starting point of each chip remains consistent.

[0098] As another implementation of the present invention, the over-temperature detection adjustment method also includes: detecting the output current of the over-temperature detection module 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 over-temperature detection module falls within the preset current range, so that the over-temperature shutdown point of each chip remains consistent.

[0099] Embodiment 2

[0100] like Fig.10 As shown, this embodiment provides a constant current control circuit 1, and the constant current control circuit 1 includes:

[0101] The over-temperature detection module 11 and the operational amplifier module 12;

[0102] like Fig.10 As shown, the first input terminal of the operational amplifier module 12 receives the current sampling signal CS via the series resistor R3, 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 12 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.

[0103] like Fig.10 As shown, the over-temperature detection module 11 is connected to the first input terminal of the operational amplifier module 12, and generates a current signal Itsc that changes linearly with increasing temperature when it is detected that the temperature is greater than or equal to a preset value.

[0104] Specifically, the circuit structure of the over-temperature detection module 11 is shown in the first embodiment, which will not be described in detail here. In this embodiment, when the temperature is less than the preset value, the output current of the over-temperature detection module 11 is 0; when the over-temperature detection module 11 is over-temperature, the current Itsc is provided to the first input terminal of the operational amplifier module 12 (that is, when the temperature reaches the preset value, the current starts to be output, and as the temperature increases, the output current Itsc changes linearly) to adjust the switch control signal output by the operational amplifier module 12, and then realize the over-temperature current reduction function by adjusting the power switch. The preset value can be set according to actual needs, which will not be described in detail here.

[0105] like Fig.10As shown, this embodiment also provides a constant current control system, and the constant current control system includes:

[0106] The power switch tube Q1, the sampling circuit 2 and the constant current control circuit 1 of this embodiment.

[0107] like Fig.10 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 2. In this embodiment, the sampling circuit 2 is implemented by a sampling resistor Rcs.

[0108] like Fig.10 As shown, the input end of the constant current control circuit 1 is connected to the output end of the sampling circuit 2, and the output end is connected to the gate of the power switch tube Q1.

[0109] Specifically, when it is detected that the temperature does not exceed the preset value, the constant current control circuit 1 controls the power switch tube Q1 based on the difference between the sampling signal CS output by the sampling circuit 2 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 2, 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 11 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.

[0110] 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 12 generates a switch control signal of the power switch tube Q1. The over-temperature detection module 11 generates a current Itsc on the series resistor R3, and the potential VINN of the first input terminal of the operational amplifier module 12 is VINN=VCS+Itsc*R3 through the series resistor R3. After 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 11 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*R3, and VCS tends to zero at this time.

[0111] Embodiment 3

[0112] like Fig.11As shown, this embodiment provides a constant current control circuit 1 and a constant current control system, which is different from the second embodiment in that the over-temperature detection module 11 is connected to the second input end of the operational amplifier module 12, that is, the same input end as the reference signal VREF.

[0113] Specifically, the first input of the operational amplifier module 12 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 IPTAT acting on the resistor R4. The overtemperature detection module 11 is connected to the second input terminal of the operational amplifier module 12, 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)*R4. When the reference signal VREF gradually drops to zero, the voltage VCS on the sampling input terminal CS also drops to zero.

[0114] Embodiment 4

[0115] This embodiment provides a constant current control circuit 1 and a constant current control system, which are different from the second and third embodiments in that the operational amplifier module 12 in the second and third embodiments is replaced by a comparison module 13; and further includes a pulse width modulation module 14, which is connected to the output end of the comparison module 13 and adjusts the pulse width based on the comparison result to obtain a switch control signal. Fig.12 The 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.11 ; 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.

[0116] In summary, the present invention provides a constant current control circuit, system, over-temperature detection module and adjustment method. The constant current control circuit includes: an operational amplifier unit, an output current linear adjustment unit and a first adjustment unit; the input end of the operational amplifier unit receives a positive temperature coefficient voltage and a temperature detection voltage respectively, and amplifies and outputs the difference between the temperature detection voltage and the positive temperature coefficient voltage; the output current linear adjustment unit is connected to the output end of the operational amplifier unit, 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 first adjustment unit acts on the input end of the positive temperature coefficient voltage or the temperature detection voltage, and adjusts 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 input and output of the over-temperature detection module of the present invention change linearly, and can be used for the over-temperature current reduction circuit. The over-temperature current reduction starting point can be highly consistent by adjusting the circuit; the output current of the transconductance amplifier is additionally adjusted to further ensure the consistency of the over-temperature shutdown point; it is suitable for a constant current control system, and the constant current control system can be a linear constant current or a switch-type PWM constant current; a small amount of transistors are added on the existing basis, the structure is simple, and the R&D cost is low. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0117] 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, an output current linear adjustment 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 amplifies and outputs a difference between the temperature detection voltage and the positive temperature coefficient voltage; The output current linear adjustment unit is connected to the output end of the operational amplifier unit, and generates a current signal that changes linearly with the difference between the temperature detection voltage and the positive temperature coefficient voltage when the temperature detection voltage is less than the positive temperature coefficient voltage; 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 output current linear adjustment unit includes a first PMOS tube, a second PMOS tube, a first NMOS tube and a second NMOS tube; The first PMOS tube, the second PMOS tube and the first NMOS tube are connected in series between a power supply and a ground in sequence, the gate of the first PMOS tube receives a bias voltage, the gate of the second PMOS tube receives the temperature detection voltage, the gate of the first NMOS tube is connected to the output end of the operational amplifier unit; the source of the second NMOS tube is connected to the drain of the second PMOS tube, the gate is connected to the source of the second PMOS tube, and the drain outputs the current signal.

3. The over-temperature detection module according to claim 2, characterized in that: When the temperature detection voltage is less than or equal to the positive temperature coefficient voltage, the current flowing through the first PMOS tube is half of the sum of the currents flowing through the input pair of tubes of the operational amplifier unit.

4. The over-temperature detection module according to claim 1, characterized in that: The over-temperature detection module further includes an output unit; the output unit is connected to the output end of the output current linear adjustment unit, and proportionally amplifies the current output by the output current linear adjustment unit.

5. The over-temperature detection module according to claim 4, characterized in that: The over-temperature detection module further includes a second trimming unit connected to the output end of the output unit to trim 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.

6. The over-temperature detection module according to any one of claims 1 to 5, characterized in that: The first trimming unit includes a trimming control unit, N trimming resistors and N switches, where N is a natural number greater than or equal to 2; the N trimming resistors are connected in series in sequence; the N switches correspond to the N trimming resistors one by one, and are respectively connected in parallel to the two ends of the corresponding trimming resistors; the trimming control unit is used to generate a control signal for the switch; When the first trimming unit is set at the input end of the positive temperature coefficient voltage, each trimming resistor is set between the input end of the positive temperature coefficient voltage and the ground, and is connected in series with the voltage divider resistor at the input end of the positive temperature coefficient voltage; when the first trimming unit is set at the input end of the temperature detection voltage, each trimming resistor is set between the input end of the temperature detection voltage and the temperature detection device.

7. The over-temperature detection module according to claim 6, characterized in that: The resistance values ​​of the trimming resistors increase in turn by 2 times.

8. 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 7; The operational amplifier module has a first input terminal receiving a current sampling signal, a second input terminal receiving a reference signal, and an output terminal outputting 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 current signal that changes linearly with the increase of temperature when it is detected that the temperature is greater than or equal to 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.

9. 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 7; 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.

10. 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 8 or 9; 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.

11. A method for adjusting over-temperature detection, characterized in that: The over-temperature detection adjustment method includes: Providing at least two chips, each of which is provided with an over-temperature detection module according to any one of claims 1 to 7; At room temperature, the voltage of the positive temperature coefficient voltage input terminal and the voltage of the temperature detection voltage input terminal on each chip are tested respectively, and the voltage difference between the two input terminals is calculated; 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, so that the starting inflection point of the over-temperature drop current of each chip remains consistent.

12. The over-temperature detection adjustment method according to claim 11, characterized in that: The method for trimming the corresponding positive temperature coefficient voltage input terminal or the temperature detection voltage input terminal includes: calculating the difference between the actual voltage difference and the middle value of the preset voltage difference range, and adjusting the input terminal voltage in units of minimum step length according to the difference.

13. The over-temperature detection adjustment method according to claim 11 or 12, characterized in that: The over-temperature detection adjustment method also includes: detecting the output current of the over-temperature detection module 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 over-temperature detection module falls within the preset current range, so that the over-temperature shutdown point of each chip remains consistent.

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