高端MOS管驱动电路应用笔记.pdf

Application Note AN-978 HV Floating MOS-Gate Driver ICs (HEXFET is a trademark of International Rectifier) Table of Contents Page Gate drive requirement of high-side devices 2 A typical block diagram 3 How to select the bootstrap components 5 How to calculate the power dissipation in an MGD 6 How to deal with negative transients on the Vs pin 9 Layout and other general guidelines 11 How to boost gate drive current to drive modules 14 How to provide a continuous gate drive 17 How to generate a negative gate bias 19 How to drive a buck converter 22 Dual forward converter and switched reluctance motor drives 24 Full bridge with current mode control 24 Brushless and induction motor drives 26 Push-pull 27 High-side P-channel 27 Troubleshooting guidelines 28 AN-978 RevD 1 1. GATE DRIVE REQUIREMENTS OF HIGH-SIDE DEVICES The gate drive requirements for a power MOSFET or IGBT utilized as a high-side switch (the drain is connected to the high voltage rail, as shown in Figure 1) driven in full enhancement (i.e., lowest voltage drop across its terminals) can be summarized as follows: 1. Gate voltage must be 10 V to 15 V higher than the source voltage. Being a high-side switch, such gate voltage would have to be higher than the rail voltage, which