®
RT7274/79/80/81
2A, 18V, 700kHz ACOT
TM
Synchronous Step-Down Converter
General Description
The RT7274/79/80/81 is a synchronous step-down DC/
DC converter with Advanced Constant On-Time (ACOT
TM
)
mode control. It achieves high power density to deliver up
to 2A output current from a 4.5V to 18V input supply. The
proprietary ACOT
TM
mode offers an optimal transient
response over a wide range of loads and all kinds of ceramic
capacitors, which allows the device to adopt very low ESR
output capacitor for ensuring performance stabilization. In
addition, RT7274/79/80/81 keeps an excellent constant
switching frequency under line and load variation and the
integrated synchronous power switches with the ACOT
TM
mode operation provides high efficiency in whole output
current load range. Cycle-by-cycle current limit provides
an accurate protection by a valley detection of low side
MOSFET and external soft-start setting eliminates input
current surge during startup. Protection functions indude
thermal shutdown for RT7274/79/80/81; output under
voltage protection and output over voltage protection for
RT7279/80 only.
Features
ACOT
TM
Mode Enables Fast Transient Response
4.5V to 18V Input Voltage Range
2A Output Current
High Efficient Internal N-MOSFET Optimized for
Lower Duty Cycle Applications
Ω
105mΩ Internal Low Side N-MOSFET
Advanced Constant On-Time Control
Allows Ceramic Output Capacitor
700kHz Switching Frequency
Adjustable Output Voltage from 0.765V to 8V
Adjustable and Pre-biased Soft-Start
Cycle-by-Cycle Current Limit
Input Under Voltage Lockout
Thermal Shutdown
RoHS Compliant and Halogen Free
Applications
Industrial and Commercial Low Power Systems
Computer Peripherals
LCD Monitors and TVs
Green Electronics/Appliances
Point of Load Regulation for High-Performance DSPs,
FPGAs, and ASICs
Simplified Application Circuit
V
IN
RT7274/79/80/81
VIN
SW
VINR*
Input Signal
Power Good
EN
PGOOD*
PVCC
SS
BOOT
FB
GND
VOUT*
PGND*
V
OUT
* : VINR pin for TSSOP-14 (Exposed Pad) only.
VOUT pin for TSSOP-14 (Exposed Pad) only.
PGND pin for TSSOP-14 (Exposed Pad) only.
PGOOD pin for TSSOP-14 (Exposed Pad) only.
Copyright
©
2013 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS7274/79/80/81-01
February 2013
www.richtek.com
1
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
