HB

PWM

Controller

VIN

T1

0.1 µF

1.0 µF

VDD

VCC

OUT1

OUT2

VDD

HI

LI

VSS

HS

LO

HO

Optional external

fast recovery diode

LM5101A

LM5100A, LM5100B, LM5100C

LM5101A, LM5101B, LM5101C

SNOSAW2Q – SEPTEMBER 2006 – REVISED NOVEMBER 2015

www.ti.com

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

9.1 Application Information

To affect fast switching of power devices and reduce associated switching power losses, a powerful gate driver is

employed between the PWM output of controllers and the gates of the power semiconductor devices. Also, gate

drivers are indispensable when it is impossible for the PWM controller to directly drive the gates of the switching

devices. With the advent of digital power, this situation will be often encountered because the PWM signal from

the digital controller is often a 3.3-V logic signal which cannot effectively turn on a power switch. 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

because 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 from the controller into the driver.

The LM5100A/B/C and LM5101A/B/C are the high voltage gate drivers that are designed to drive both the high-

side and low-side N-Channel MOSFETs in a half-bridge/full bridge configuration or in a synchronous buck circuit.

The floating high side driver is capable of operating with supply voltages up to 100 V. This allows for N-Channel

MOSFET control in half-bridge, full-bridge, push-pull, two switch forward and active clamp topologies. The

outputs are independently controlled. Each channel is controlled by its respective input pins (HI and LI), allowing

full and independent flexibility to control on and off state of the output.

9.2 Typical Application

Figure 25. LM5101A Driving MOSFETs in Half-Bridge Configuration

16

Submit Documentation Feedback

Copyright © 2006–2015, Texas Instruments Incorporated

Product Folder Links: LM5100A LM5100B LM5100C LM5101A LM5101B LM5101C