RT6296D

Copyright © 2015 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS6296D-00

July

2015

www.richtek.com

3

Function Block Diagram

EN/SYNC

+

-

UV

Comparator

Oscillator

0.4V

Internal

Regulator

Shutdown

Comparator

BOOT

GND

FB

HS Switch

Current

Comparator

+

-

EA

11µA

Power

Stage &

Deadtime

Control

+

-

1.4V

+

Slope

Compensation

LS Switch

Current

Comparator

UVLO

Logic &

Protection

Control

BOOT

UVLO

Current

Sense

Current

Sense

PVCC

SS

50pF

1pF

400k

SW

VIN

0.807V

Operation

Under Voltage Lockout Threshold

The IC includes an input Under Voltage Lockout

Protection (UVLO). If the input voltage exceeds the

UVLO rising threshold voltage (3.9V), the converter

resets and prepares

the PWM for operation. If the input voltage falls below

the UVLO falling threshold voltage (3.25V) during

normal operation, the device stops switching. The

UVLO rising and falling threshold voltage includes a

hysteresis to prevent noise caused reset.

Chip Enable

The EN pin is the chip enable input. Pulling the EN pin

low (<1.1V) will shutdown the device. During shutdown

mode, the RT6296D

’s quiescent current drops to lower

than 1

A. Driving the EN pin high (>1.6V) will turn on

the device.

Operating Frequency and Synchronization

The internal oscillator runs at 500kHz (typ.) when the

EN/SYNC pin is at logic-high level (>1.6V). If the EN

pin is pulled to low-level over 8

s, the IC will shut down.

The RT6296D can be synchronized with an external

clock ranging from 200kHz to 2MHz applied to the

EN/SYNC pin. The external clock duty cycle must be

from 20% to 80% with logic-high level = 2V and

logic-low level = 0.8V.

Internal Regulator

The internal regulator generates 5V power and drive

internal circuit. When VIN is below 5V, PVCC will drop

with VIN. A capacitor (>0.1

F) between PVCC and

GND is required.

Soft-Start Function

The RT6296D provides external soft-start function. The

soft-start function is used to prevent large inrush

current while converter is being powered-up. The

soft-start timing can be programmed by the external