LM5177DCPR datasheet(34/60 Pages) TI2

34 / 60 page

VCC

HBx

HOx

SWx

PGND

LOx

GATE

LOG IC

DELAY

LEV EL

SHIFTER

V(VCC)

PWM

VT-(BOOT,UVLO)

OV_ CL AMP

Figure 7-19. Functional Block Diagram Gate Driver

External Gate Driver Support

The LM5177 supports external gate driver by the HOx_LL pins. These pins provide the two high-side gate drive

signals referenced to ground. By connecting the HOx_LL and LOx signals to a external gate driver the external

power FETs can be controlled by the external gate driver. This feature for example is helpful in case no logic

level FET is available and the application need to drive gate voltages higher the one the integrated gate drive

supports.

The external bootstrap capacitors on HBx still needs to be placed in the schematic as the internal current sense

amplifier is still supplied trough this pins. The HOx pin can be left floating. Make sure the supply voltage V(extGD)

for each external gate driver maintains the necessary requirements for a 4-switch Buck-Boost such as 100%

duty cycle and the isolation between each side of the full-bridge. Below Simplified Schematic External Gate

Driver support show a functional block diagram of a possible connection for a external gate driver.

LM5177

SNVSBU4F – JUNE 2022 – REVISED JANUARY 2025

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LM5177DCPR Datasheet(PDF) 34 Page - Texas Instruments