RT9624D datasheet(3/13 Pages) RICHTEK

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RT9624D

DS9624D-04

July 2015

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

Function Block Diagram

Shoot-Through

Protection

Turn Off

Detection

Shoot-Through

Protection

Tri-State

Detect

VCC

PWM

Internal

VDD

BOOT

UGATE

PHASE

LGATE

GND

VCC

POR

Bootstrap

Control

Operation

POR (Power On Reset)

POR block detects the voltage at the VCC pin. When the

VCC pin voltage is higher than POR rising threshold, POR

block output is high. POR output is low when VCC is not

higher than POR rising threshold. When the POR block

output is high, UGATE and LGATE can be controlled by

PWM input voltage. If the POR block output is low, both

UGATE and LGATE will be pulled to low.

Tri-State Detect

When both POR block output and EN pin voltages are

high, UGATE and LGATE can be controlled by PWM input.

There are three PWM input modes, which are high, low,

and shutdown state. If PWM input is within the shutdown

window, both UGATE and LGATE output are low. When

PWM input is higher than its rising threshold, UGATE is

high and LGATE is low. When PWM input is lower than

its falling threshold, UGATE is low and LGATE is high.

Bootstrap Control

Bootstrap control block controls the integrated bootstrap

switch. When LGATE is high (low side MOSFET is turned

on), the bootstrap switch is turned on to charge the

bootstrap capacitor connected to BOOT pin. When LGATE

is low (low side MOSFET is turned off), the bootstrap switch

is turned off to disconnect VCC pin and BOOT pin.

Turn-Off Detection

Turn-off detection block detects whether high side

MOSFET is turned off by monitoring PHASE pin voltage.

To avoid shoot-through between high side and low side

MOSFETs, low side MOSFET can be turned on only after

high side MOSFET is effectively turned off.

Shoot-Through Protection

Shoot-through protection block implements the dead time

when both high side and low side MOSFETs are turned

off. With shoot-through protection block, high side and

low side MOSFET are never turned on simultaneously.

Thus, shoot-through between high side and low side

MOSFETs is prevented.

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