PDF《Application Report》

1 SLUA618ACMarch 2017CRevised October

2018 Submit Documentation Feedback Copyright ? 2017C2018, Texas Instruments Incorporated Fundamentals of MOSFET and IGBT Gate Driver Circuits Application Report SLUA618ACMarch 2017CRevised October

2018 Fundamentals of MOSFET and IGBT Gate Driver Circuits Laszlo Balogh ABSTRACT The main purpose of this application report is to demonstrate a systematic approach to design high performance gate drive circuits for high speed switching applications.

It is an informative collection of topics offering a one-stop-shopping to solve the most common design challenges. Therefore, it should be of interest to power electronics engineers at all levels of experience. The most popular circuit solutions and their performance are analyzed, including the effect of parasitic components, transient and extreme operating conditions. The discussion builds from simple to more complex problems starting with an overview of MOSFET technology and switching operation. Design procedure for ground referenced and high side gate drive circuits, AC coupled and transformer isolated solutions are described in great details. A special section deals with the gate drive requirements of the MOSFETs in synchronous rectifier applications. For more information, see the Overview for MOSFET and IGBT Gate Drivers product page. Several, step-by-step numerical design examples complement the application report. This document is also available in Chinese: MOSFET 和IGBT 栅极驱动器电路的基本原理 Contents

1 Introduction

2 2 MOSFET Technology

2 3 Ground-Referenced Gate Drive

15 4 Synchronous Rectifier Drive

22 5 High-Side Non-Isolated Gate Drives.25

6 AC-Coupled Gate-Drive Circuits

36 7 Transformer-Coupled Gate Drives

38 8 Summary

45 9 References

47 List of Figures

1 Power MOSFET Device Types

4 2 Power MOSFET Models

6 3 Simplified Clamped Inductive Switching Model.9

4 MOSFET Turn-On Time Intervals.10

5 MOSFET Turn-Off Time Intervals.11

6 Typical Gate Charge vs. Gate-to-Source Voltage

12 7 Gate-Drive Resonant Circuit Components.14

8 Direct Gate-Drive Circuit

15 9 Gate-Drive With Integrated Bipolar Transistors

17 10 Bipolar Totem-Pole MOSFET Driver

17 11 MOSFET-Based Totem-Pole Driver

18 12 Simple Turn-Off Speed Enhancement Circuit

19 13 Local pnp Turn-Off Circuit.20

14 Local NPN Self-Biasing Turn-Off Circuit

20 15 Improved N-Channel MOSFET-Based Turn-off Circuit

21 Introduction www.ti.com

2 SLUA618ACMarch 2017CRevised October

2018 Submit Documentation Feedback Copyright ? 2017C2018, Texas Instruments Incorporated Fundamentals of MOSFET and IGBT Gate Driver Circuits

16 Simplified Synchronous Rectification Model.22

17 Synchronous Switching Model

24 18 Direct Drive for P-Channel MOSFET

26 19 Open Collector Drive for PMOS Device.26

20 Level-Shifted P-Channel MOSFET Driver

27 21 Direct Drive of N-Channel MOSFET.28

22 Turn-Off of High-Side N-Channel MOSFET

29 23 Integrated Bootstrap Driver

30 24 Integrated Bootstrap Driver

31 25 Typical Level-Shifter in High-Voltage Driver IC

31 26 High Voltage Driver IC for Bootstrap Gate Drive.32

27 Protecting the SRC Pin.32

28 Bootstrap Bypassing Example.33

29 Bootstrap Start-Up Circuit.34

30 Capacitive Currents in High-Side Applications

35 31 Capacitively-Coupled MOSFET Gate Drive

36 32 Normalized Coupling Capacitor Voltage as a Function of Duty Ratio.37

33 Single-Ended Transformer-Coupled Gate Drive

39 34 Driver Output Current With Transformer-Coupled Gate Drive