RT9624D datasheet(3/13 Pages) RICHTEK

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RT9624D

DS9624D-00

September 2012

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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