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LM5134

SNVS808C – MAY 2012 – REVISED FEBRURARY 2016

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8 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.

8.1 Application Information

High-current gate-driver devices are required in switching power applications for a variety of reasons. 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. Further,

gate drivers are indispensable when there are times that the PWM controller cannot directly drive the gates of

the switching devices. With advent of digital power, this situation is often encountered because 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) to

fully turn on the power device and minimize conduction losses. Because traditional buffer-drive circuits based on

NPN/PNP bipolar transistors in totem-pole arrangement, being emitter-follower configurations, lack level-shifting

capability, the circuits prove inadequate with digital power.

Gate drivers effectively combine both the level-shifting and buffer-drive functions. Gate drivers can also perform

other tasks, 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,

and reducing power dissipation and thermal stress in controllers by moving gate-charge power losses into itself.

Finally, emerging wide-bandgap power-device technologies, such as GaN based switches capable of supporting

very high switching frequency operation, are driving 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 with a simplified system design.

8.2 Typical Application

Figure 24. Application Schematic