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MOSFET protection circuit

A technology for protecting circuits and circuits, applied in electrical components, electronic switches, pulse technology, etc., can solve problems such as large parasitic induced voltage, MOSFET overvoltage damage, etc., to reduce reverse induced voltage, delay switching speed, and reduce overvoltage The effect of the risk of harm

Pending Publication Date: 2018-01-09
YUNNAN POWER GRID CO LTD ELECTRIC POWER RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] This application provides a MOSFET protection circuit, which is used to solve the problem that when the MOSFET Q3 is quickly turned off, the parasitic induced voltage generated by the parasitic inductance L in the circuit is too large, thus causing the MOSFET to be easily damaged by overvoltage

Method used

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Embodiment Construction

[0025] Such as figure 1 In the switching amplifier shown, MOSFET Q1 and MOSFET Q2 form a push-pull switch, which is used to control MOSFET Q3 to be turned on or off. In order to pursue the performance of the switching amplifier, in current switching amplifiers, the MOSFET Q3 mostly uses a high-power device, and the high-power MOSFET Q3 has a high switching frequency, which can be turned on or off quickly. However, when the high-power MOSFET Q3 is working, the parasitic inductance L existing in the circuit will generate an obvious reverse induced voltage when the MOSFET Q3 switches rapidly, especially when the switching amplifier is over-current or short-circuited, the parasitic inductance L will generate The reverse induced voltage will be higher. The reverse induced voltage and the power supply voltage act together on MOSFET Q3. Once the voltage carried by MOSFET Q1 exceeds the maximum withstand voltage of MOSFET Q1, it will cause overvoltage damage to MOSFET Q3. The presen...

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Abstract

The invention discloses an MOSFET protection circuit including a voltage stabilizing circuit S1, a delay circuit S2 and an energy supplementing circuit S3. The voltage stabilizing circuit S1 includesa voltage stabilizing diode D1. The negative electrode of the voltage stabilizing diode D1 is connected with a D electrode of the MOSFET Q3. The positive electrode of the voltage stabilizing diode D1is connected with the delay circuit S2 and the energy supplementing circuit S3. The other end of the delay circuit S2 is connected with a G electrode of an MOSFET Q2. The other end of the energy supplementing circuit S3 is connected with a G electrode of the MOSFET Q3. According to the invention, through reducing the switching speed of the MOSFET Q3, reverse induction voltage generated by a parasitic inductor L is reduced and further the voltage withstanding risks of the MOSFET Q3 are reduced.

Description

technical field [0001] The present application relates to the field of MOSFET protection, in particular to a protection circuit for MOSFET. Background technique [0002] MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor, Metal-Oxide Semiconductor Field-Effect Transistor) is a field-effect transistor that has been widely used as a current amplifier or switch controller. For example, an amplifier is a device realized by utilizing the ability of a MOSFET to amplify current. [0003] figure 1 is a circuit diagram of a switching amplifier, such as figure 1 As shown, the switching amplifier contains a plurality of MOSFETs, wherein MOSFET Q3 is used to amplify current; MOSFET Q1 and MOSFET Q2 form a push-pull switch, which is used to control MOSFET Q3 to be turned on or off. The use process of the switching amplifier includes: when the driving signal MOS Driver is low voltage, MOSFET Q1 is turned on, so that MOSFET Q3 is turned on; when the driving signal MOS Driver is h...

Claims

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Application Information

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IPC IPC(8): H03K17/08
Inventor 许守东陈勇张丽
Owner YUNNAN POWER GRID CO LTD ELECTRIC POWER RES INST
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