5

10

15

20

0

4

8

12

16

20

Supply Voltage (V)

G008

2

4

6

8

10

0

4

8

12

16

20

Supply Voltage (V)

G009

UCC27517

UCC27516

www.ti.com

SLUSAY4B – MARCH 2012 – REVISED JUNE 2012

TYPICAL CHARACTERISTICS (continued)

RISE TIME

FALL TIME

vs

vs

SUPPLY VOLTAGE

SUPPLY VOLTAGE

Figure 17.

Figure 18.

APPLICATION INFORMATION

Introduction

High-current gate driver devices are required in switching power applications for a variety of reasons. In order to

effect fast switching of power devices and reduce associated switching power losses, a powerful gate driver can

be employed between the PWM output of controllers and the gates of the power semiconductor devices. Further,

gate drivers are indispensable when sometimes it is just not feasible to have the PWM controller directly drive

the gates of the switching devices. With advent of digital power, this situation will be often encountered since the

PWM signal from the digital controller is often a 3.3-V logic signal which is not capable of effectively turning on a

power switch. A level shifting circuitry is needed to boost the 3.3-V signal to the gate-drive voltage (such as 12 V)

in order to fully turn on the power device and minimize conduction losses. Traditional buffer drive circuits based

on NPN/PNP bipolar transistors in totem-pole arrangement, being emitter follower configurations, prove

inadequate with digital power since they lack level-shifting capability. Gate drivers effectively combine both the

level-shifting and buffer-drive functions. Gate drivers also find other needs such as minimizing the effect of high-

frequency switching noise by locating the high-current driver physically close to the power switch, driving gate-

drive transformers and controlling floating power-device gates, reducing power dissipation and thermal stress in

controllers by moving gate charge power losses into itself. Finally, emerging wide band-gap power device

technologies such as GaN based switches, which are capable of supporting very high switching frequency

operation, are driving very special requirements in terms of gate drive capability. These requirements include

operation at low VDD voltages (5 V or lower), low propagation delays and availability in compact, low-inductance

packages with good thermal capability. In summary gate-driver devices are extremely important components in

switching power combining benefits of high-performance, low cost, component count and board space reduction

and simplified system design.

Copyright © 2012, Texas Instruments Incorporated

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