Drain-source voltage sampling circuit of power tube

Abstract

The invention discloses a drain-source voltage sampling circuit of a power tube. The drain-source voltage sampling circuit comprises a voltage compensation module, an operational amplifier and a sampling output module. The voltage compensation module is used for compensating input voltage and output voltage and outputting compensated first detection voltage and second detection voltage, the inverted input end of the operational amplifier is used for receiving the first detection voltage, the normal input end of the operational amplifier is used for receiving the second detection voltage, and the output end of the operational amplifier is connected with the sampling output module. Specifically, the operational amplifier works in a negative feedback state so as to control the sampling output module to output sampling current representing drain-source voltage of the power tube. The first detection voltage and the second detection voltage after compensation are always greater than the overdrive voltage of a sampling transistor in the sampling output module, so that the sampling transistor can work normally in a full voltage range, the problem of sampling distortion is solved, and the overall performance index of the system is greatly improved.

Description

technical field [0001] The present invention relates to the technical field of integrated circuits, in particular to a drain-source voltage sampling circuit of a power transistor. Background technique [0002] In the power system, by controlling the switch-type power tube, such as IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) or MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor, Metal-Oxide-Semiconductor Field-Effect Transistor) conduction And turn off to realize the transformation of electric energy and the stability of output voltage. [0003] Since the power tube needs to flow a large current and its working environment is relatively complicated, many protection circuits are required to protect the power tube. Therefore, in many applications, it is usually necessary to detect the drain-source voltage of the power tube and convert it to It is the current that has a linear relationship with the drain-source voltage difference, so that ...

AI Technical Summary

Problems solved by technology

[0005] The existing drain-source voltage sampling circuit 100 of the power transistor has the following disadvantages: in order to ensure the normal operation of the circuit, the existing drain-source voltage sampling circuit 100 requires that both the input voltage Vin and the output voltage Vout must be greater than the gate-source voltage Vgs of the transistor Mp1 , which limits the minimum voltage range of the input voltage Vin

Secondly, when the output voltage Vout is lower than the gate-source voltage Vgs of the transistor Mp1, it will cause sampling distortion, thus limiting the sampling range of the drain-source voltage

Finally, when the output voltage Vout is equal to 0, the voltage difference between the drain and source of the power transistor P1 under test is the largest, and the power consumption of the power transistor P1 is the largest. If the problem of sampling distortion occurs at this time, it may cause The problem that the power tube P1 cannot be effectively protected in time, thus affecting the overall performance index of the system

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