RT7255

Copyright © 2015 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS7255-00

June

2015

www.richtek.com

3

Function Block Diagram

Reg

UGATE

LGATE

Driver

BOOT

PVCC

Control

VIBIAS

On-Time

Min.

Off

Ripple

Gen.

Comparator

SS

SW

GND

EN

OC

+

-

-

PVCC

UV & OV

VIN

PWRGN

PGOOD

SW

GND SW

SW

EN

FB

PVCC

Operation

The RT7255 is a synchronous step-down converter

with advanced constant on-time control mode. Using

the ACOT control mode can reduce the output

capacitance and fast transient response. It can

minimize

the

component

size

without

additional

external compensation network.

Current Protection

The inductor current is monitored via the internal

switches cycle-by-cycle. Once the output voltage drops

under UV threshold, the RT7255 will enter hiccup

mode.

UVLO Protection

To protect the chip from operating at insufficient supply

voltage, the UVLO is needed. When the input voltage

of VIN is lower than the UVLO falling threshold voltage,

the device will be lockout.

Thermal Shutdown

When the junction temperature exceeds the OTP

threshold value, the IC will shut down the switching

operation. Once the junction temperature cools down

and is lower than the OTP lower threshold, the

converter will autocratically resume switching.