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MOSFET current detection circuit and method

A current detection circuit and current detection technology, applied in the direction of measuring current/voltage, measuring device, measuring electrical variables, etc., can solve the problems of large temperature influence and low detection accuracy, and achieve good temperature characteristics, high detection accuracy, and elimination of influence. Effect

Pending Publication Date: 2020-02-14
合肥仙湖半导体科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to solve the problems of low detection accuracy and greater influence by temperature, and provide a MOSFET current detection circuit and method

Method used

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  • MOSFET current detection circuit and method
  • MOSFET current detection circuit and method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Embodiment 1: as figure 1 As shown, a MOSFET current detection circuit includes a power switch tube Q4, a detection switch tube Q3, a thermistor R3, a fixed value resistor R2, and a voltage detection circuit; the power switch tube Q4 is switched synchronously with the detection switch tube Q3 , when the power switch tube Q4 is turned on, the detection circuit voltage corresponds to the voltage of the DS terminal of the power switch tube Q4, and then the current of the power switch tube Q4 is obtained.

[0027] The power switching tube Q4 to be detected is mirror-connected to the detection switching tube Q3, the thermistor R3 and the fixed value resistor R2 are connected in series with the detection switching tube Q3, and the thermistor R3 is connected to the detection switching tube Q3 The resistance changes correspondingly with the change of temperature, which compensates the temperature characteristic of the on-resistance of the switching tube Q3 to be detected.

[0...

Embodiment 2

[0032] Embodiment 2: as figure 2 As shown, a MOSFET current detection circuit includes a power switch tube Q1, a detection switch tube Q2, a thermistor R6, a fixed value resistor R1, and a voltage detection circuit; the power switch tube Q1 and the detection switch tube Q2 switch synchronously , when the power switch tube Q1 is turned on, the detection circuit voltage corresponds to the voltage of the DS terminal of the power switch tube Q1, and then the current of the power switch tube Q1 is obtained.

[0033] The power switching tube Q1 to be detected is mirror-connected to the detection switching tube Q2, the thermistor R6 and the fixed value resistor R1 are connected in series with the detection switching tube Q2, and the thermistor R6 is connected to the detection switching tube Q2 The resistance changes correspondingly with the change of temperature, which compensates the temperature characteristic of the on-resistance of the switching tube Q2 to be detected.

[0034] ...

Embodiment 3

[0038] Embodiment 3: as image 3 As shown, a MOSFET current detection circuit includes a power switch tube Q7, a detection switch tube Q8, a thermistor R7, a fixed value resistor R8 and a voltage detection circuit; the power switch tube Q7 is switched synchronously with the detection switch tube Q8 , when the power switch tube Q7 is turned on, the detection circuit voltage corresponds to the voltage of the DS terminal of the power switch tube Q7, and then the current of the power switch tube Q7 is obtained.

[0039] The to-be-detected power switch tube Q7 is mirror-connected to the detection switch tube Q8, the thermistor R7 and the fixed value resistor R8 are connected in series with the detection switch tube Q8, and the thermistor R7 and the to-be-detected switch tube Q8 conduct The resistance changes correspondingly with the change of temperature, which compensates the temperature characteristic of the on-resistance of the switching tube Q8 to be detected.

[0040] It also...

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Abstract

The invention provides an MOSFET current detection circuit and method. The MOSFET current detection circuit comprises a power switch tube, a detection switch tube, a thermistor, a fixed value resistorand a voltage detection circuit, wherein the power switch tube and the detection switch tube are synchronously switched on and off; and when the power switch tube is switched on, the voltage of the detection circuit corresponds to the DS end voltage of the power switch tube, and then the current of the power switch tube is obtained. The MOSFET current detection circuit and method have the advantages that the resistance value change of the thermistor and the conduction resistance value of the switch tube to be detected correspondingly change along with the temperature change so as to counteract the influence of the conduction resistance value on the detection current along with the temperature change; the detection current does not change along with the temperature change by selecting thethermistor with the proper temperature coefficient, the temperature characteristic of the conduction resistance value of the switch tube to be detected is compensated, and therefore the influence of the temperature on the measurement precision is reduced or eliminated. The detection circuit has the advantages of being high in detection precision and good in temperature characteristic.

Description

【Technical field】 [0001] The invention relates to a current detection method, in particular to a MOSFET current detection circuit and method. 【Background technique】 [0002] In switching power supplies, it is usually necessary to detect the current to control the current or prevent the current from exceeding the limit value. Most of the current detection is to achieve the detection purpose by mapping the current signal into a voltage signal; the more common method is to connect the detection resistor in series with the detected current. In the loop, the detected current is determined by the voltage across the detection resistor; however, the detection resistor will generate additional loss, especially when a large current flows through the circuit, the voltage drop generated by the detection resistor will increase, and the loss will increase. For this reason, When the detected current is larger, the resistance value of the detection resistor is required to be smaller, and th...

Claims

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Application Information

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IPC IPC(8): G01R19/00G01R19/32
CPCG01R19/00G01R19/32
Inventor 黄明乐郑春芳
Owner 合肥仙湖半导体科技有限公司
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