Temperature acquisition circuit for field effect transistor

Abstract

The utility model relates to a temperature acquisition circuit used for a field effect transistor, comprising a field effect transistor Q1, a signal amplification module and a chip used for calculating the temperature of the field effect transistor Q1, a drain electrode of the field effect transistor Q1 is respectively connected with the chip and a power supply VCC, a grid electrode of the field effect transistor Q1 is connected with one end of a resistor R4, the other end of the resistor R4 is connected with the chip, and the chip is connected with the signal amplification module. The source electrode of the field effect transistor Q1 comprises a first branch, a second branch and a third branch, the first branch is connected with one end of a resistor R5 and one end of a capacitor C3 which are connected in parallel, the other end of the resistor R5 is connected with the grid electrode of the field effect transistor Q1, the other end of the capacitor C3 is connected with one end of a resistor R4, the second branch is connected with a ground wire GND, the third branch is connected with the input end of a signal amplification module, and the input end of the signal amplification module is connected with the grid electrode of the field effect transistor Q1. And the output end of the signal amplification module is respectively connected with the chip and a ground wire GND. According to the utility model, the temperature of the field effect transistor can be measured, and the designed circuit is not easy to be interfered by the outside and has high measurement precision.

Description

Technical Field

[0001] The utility model relates to the technical field of temperature acquisition circuits, in particular to a temperature acquisition circuit for a field effect tube. Background Art

[0002] Field-effect transistors (FETs), as semiconductor devices, have a specific operating temperature range. The operating temperature range refers to the temperature range that the FET can withstand under normal working conditions. Within this range, the FET can switch and amplify signals normally. Exceeding the operating temperature range of the FET may cause the following problems: Performance degradation: Exceeding the temperature range may cause device performance degradation, such as reduced gain, threshold voltage changes, etc. Thermal runaway: In some cases, the device may enter a thermal runaway state, causing the temperature to rise rapidly and eventually damage the device. Shortened life: Working at high temperatures for a long time may shorten the service life of the device.

[0003] Therefore, manufacturers usually specify the operating temperature range of the field effect tube in the data sheet, and the temperature of the field effect tube needs to be effectively measured when used in a specific scenario circuit. Although the commonly used NTC temperature measurement circuit can measure the temperature of the field effect tube, the NTC temperature measurement circuit is greatly affected by external interference and is prone to errors. Utility Model Content

[0004] Therefore, the technical problem to be solved by the utility model is to overcome the problem that the NTC temperature measurement circuit in the prior art is greatly affected by external interference when measuring the temperature of the field effect tube, which is prone to error.

[0005] In order to solve the above technical problems, the utility model provides a temperature acquisition circuit for a field effect tube, including a field effect tube Q1, a signal amplification module and a chip for calculating the temperature of the field effect tube Q1, the drain of the field effect tube Q1 is respectively connected to the chip and the power supply VCC, the gate of the field effect tube Q1 is connected to one end of a resistor R4, the other end of the resistor R4 is connected to the chip, the source of the field effect tube Q1 includes a first branch, a second branch and a third branch, the first branch is respectively connected to a resistor R5 and one end of a capacitor C3 connected in parallel, the other end of the resistor R5 is connected to the gate of the field effect tube Q1, the other end of the capacitor C3 is connected to one end of the resistor R4, the second branch is connected to a ground wire GND, the third branch is connected to an input end of the signal amplification module, and the output end of the signal amplification module is respectively connected to the chip and the ground wire GND;

[0006] The signal amplification module includes an operational amplifier OA1, a resistor R1 and a capacitor C1, one end of the resistor R1 is respectively connected to the third branch of the source of the field effect transistor Q1 and one end of the capacitor C1; the other end of the resistor R1 is connected to the positive input end of the operational amplifier OA1, and the other end of the capacitor C1 is respectively connected to the negative input end of the operational amplifier OA1 and the ground wire GND; the output end of the operational amplifier OA1 is respectively connected to the chip and the ground wire GND.

[0007] In one embodiment of the present invention, the output end of the operational amplifier OA1 is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the chip and the ground wire GND respectively.

[0008] In an embodiment of the present invention, the other end of the resistor R3 is connected to the ground line GND via the capacitor C2.

[0009] In one embodiment of the present invention, the other end of the capacitor C1 is connected to the negative input end of the operational amplifier OA1 through the resistor R2.

[0010] In an embodiment of the present invention, the second branch of the source of the field effect transistor Q1 is connected to the ground line GND through the resistor RS1.

[0011] In one embodiment of the present invention, the chip model is SPC7L64BLL1.

[0012] In an embodiment of the present invention, the value of the resistor RS1 is 5 mΩ.

[0013] In an embodiment of the present invention, the value of the resistor R1 is 200Ω.

[0014] In an embodiment of the present invention, the value of the resistor R2 is 200Ω.

[0015] In an embodiment of the present invention, the value of the resistor R3 is 10KΩ, and the value of the resistor R4 is 22Ω.

[0016] The above technical solution of the utility model has the following advantages compared with the prior art:

[0017] The temperature acquisition circuit for field effect tubes of the utility model can not only measure the temperature of the field effect tubes, but also is not easily affected by external interference, has high measurement accuracy, and is easy to promote on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the content of the utility model easier to understand, the utility model is further described in detail according to the specific embodiments of the utility model in combination with the accompanying drawings, wherein

[0019] Figure 1 It is a temperature collection circuit diagram for a field effect tube in an embodiment of the utility model. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0021] Reference Figure 1 As shown, the utility model relates to a temperature acquisition circuit for a field effect tube, comprising a field effect tube Q1, a signal amplification module and a chip for calculating the temperature of the field effect tube Q1, the drain of the field effect tube Q1 is respectively connected to the chip and the power supply VCC, the gate of the field effect tube Q1 is connected to one end of a resistor R4, the other end of the resistor R4 is connected to the chip, the source of the field effect tube Q1 comprises a first branch, a second branch and a third branch, the first branch is respectively connected to a resistor R5 and one end of a capacitor C3 connected in parallel, the other end of the resistor R5 is connected to the gate of the field effect tube Q1, the other end of the capacitor C3 is connected to one end of the resistor R4, the second branch is connected to a ground wire GND, the third branch is connected to an input end of the signal amplification module, and the output end of the signal amplification module is respectively connected to the chip and the ground wire GND.

[0022] The signal amplification module includes an operational amplifier OA1, a resistor R1 and a capacitor C1, one end of the resistor R1 is respectively connected to the third branch of the source of the field effect transistor Q1 and one end of the capacitor C1; the other end of the resistor R1 is connected to the positive input end of the operational amplifier OA1, and the other end of the capacitor C1 is respectively connected to the negative input end of the operational amplifier OA1 and the ground wire GND; the output end of the operational amplifier OA1 is respectively connected to the chip and the ground wire GND.

[0023] The drain of the field effect transistor Q1 of this embodiment is connected to the chip, in order to obtain the drain voltage of the field effect transistor Q1 (ie Figure 1 The voltage at point U in the middle).

[0024] Furthermore, the output end of the operational amplifier OA1 is connected to one end of the resistor R3, and the other end of the resistor R3 is connected to the chip and the ground wire GND respectively.

[0025] Furthermore, the other end of the resistor R3 is connected to a ground line GND via a capacitor C2.

[0026] Furthermore, the other end of the capacitor C1 is connected to the negative input end of the operational amplifier OA1 through the resistor R2.

[0027] Furthermore, the second branch of the source of the field effect transistor Q1 is connected to the ground line GND through the resistor RS1.

[0028] Furthermore, the value of the resistor RS1 is 5 mΩ, and its function is sampling.

[0029] Furthermore, the value of the resistor R1 is 200Ω, and its function is to limit the current.

[0030] Furthermore, the value of the resistor R2 is 200Ω, and its function is to limit the current.

[0031] Furthermore, the value of the resistor R3 is 10KΩ, and its function is to limit the current.

[0032] Furthermore, the value of the resistor R4 is 22Ω, which is used to prevent oscillation, reduce the gate charging peak current of the field effect transistor Q1, and protect the DS electrode (drain-source) from being broken down.

[0033] Furthermore, the value of the resistor R5 is 10KΩ. When the field effect transistor Q1 is turned off, the voltage difference between the source and the gate is large. At this time, adding the resistor R5 can help the charge to be released quickly, so that the field effect transistor Q1 is turned off quickly, thereby improving the response speed of the switch.

[0034] Furthermore, the functions of the capacitors C1 and C2 are filtering, and the function of the capacitor C3 is filtering to help stabilize the working state of the field effect transistor Q1.

[0035] Furthermore, the model of the chip in this embodiment is SPC7L64BLL1.

[0036] The specific method for measuring the temperature of the field effect tube Q1 in this embodiment is as follows:

[0037] See also Figure 1 , the chip obtains the voltage U at point U, and the chip obtains the voltage U at point AD_COM AD_com , the voltage U at the AD_COM point AD_com The voltage U at the COM point com After the voltage of the operational amplifier OA1, the chip can be based on the voltage U at the AD_COM point AD_com The operational amplifier OA1 pushes out the voltage U at the COM point com , so according to U AD_com and resistor RS1 to obtain the current I RS ; The chip subtracts the voltage U at point U from the voltage U at point COM com Divide by the current I RS, the chip can obtain the impedance R of the field effect tube Q1 Q1 Finally, according to the temperature and impedance curve relationship diagram of the field effect tube Q1 obtained in advance, the impedance R of the field effect tube Q1 can be calculated. Q1 If the chip does not have the function of directly calculating the temperature, you can also manually set the impedance R Q1 The temperature of the field effect tube Q1 can be obtained by combining the temperature and impedance curve. This method can obtain the temperature inside the field effect tube Q1 with high accuracy and small error.

[0038] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention of the utility model.

Claims

1. A temperature acquisition circuit for a field effect tube, characterized in that: It includes a field effect tube Q1, a signal amplification module and a chip for calculating the temperature of the field effect tube Q1, the drain of the field effect tube Q1 is respectively connected to the chip and the power supply VCC, the gate of the field effect tube Q1 is connected to one end of the resistor R4, the other end of the resistor R4 is connected to the chip, the source of the field effect tube Q1 includes a first branch, a second branch and a third branch, the first branch is respectively connected to a resistor R5 and one end of a capacitor C3 connected in parallel, the other end of the resistor R5 is connected to the gate of the field effect tube Q1, the other end of the capacitor C3 is connected to one end of the resistor R4, the second branch is connected to a ground line GND, the third branch is connected to an input end of the signal amplification module, and the output end of the signal amplification module is respectively connected to the chip and the ground line GND; The signal amplification module includes an operational amplifier OA1, a resistor R1 and a capacitor C1, one end of the resistor R1 is respectively connected to the third branch of the source of the field effect transistor Q1 and one end of the capacitor C1; the other end of the resistor R1 is connected to the positive input end of the operational amplifier OA1, and the other end of the capacitor C1 is respectively connected to the negative input end of the operational amplifier OA1 and the ground wire GND; the output end of the operational amplifier OA1 is respectively connected to the chip and the ground wire GND.

2. The temperature acquisition circuit for field effect tube according to claim 1, characterized in that: The output end of the operational amplifier OA1 is connected to one end of the resistor R3 , and the other end of the resistor R3 is connected to the chip and the ground wire GND respectively.

3. The temperature acquisition circuit for field effect tube according to claim 2, characterized in that: The other end of the resistor R3 is connected to the ground line GND via the capacitor C2.

4. The temperature acquisition circuit for field effect tube according to claim 1, characterized in that: The other end of the capacitor C1 is connected to the negative input end of the operational amplifier OA1 through the resistor R2.

5. The temperature acquisition circuit for field effect tube according to claim 1, characterized in that: The second branch of the source of the field effect transistor Q1 is connected to the ground line GND through the resistor RS1.

6. The temperature acquisition circuit for field effect tube according to claim 1, characterized in that: The model of the chip is SPC7L64BLL1.

7. The temperature acquisition circuit for field effect tube according to claim 5, characterized in that: The value of the resistor RS1 is 5 mΩ.

8. The temperature acquisition circuit for field effect tube according to claim 1, characterized in that: The value of the resistor R1 is 200Ω.

9. The temperature acquisition circuit for field effect tube according to claim 4, characterized in that: The value of the resistor R2 is 200Ω.

10. The temperature acquisition circuit for field effect tube according to claim 2, characterized in that: The value of the resistor R3 is 10KΩ, and the value of the resistor R4 is 22Ω.

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