®
RT6239A/B
9A, 18V, 500kHz, ACOTTM Synchronous Step-Down Converter
General Description
Features
Fast Transient Response
The RT6239A/B is a high-performance 500kHz, 9Astep-
down regulator with internal power switches and
synchronous rectifiers. It features quick transient response
using its Advanced Constant On-Time (ACOTTM) control
architecture that provides stable operation with small
ceramic output capacitors and without complicated
external compensation, among other benefits. The input
voltage range is from 4.5V to 18V and the output is
adjustable from 0.7V to 8V. The proprietaryACOTTM control
improves upon other fast response constant on-time
architectures, achieving nearly constant switching
frequency over line, load, and output voltage ranges. Since
there is no internal clock, response to transients is nearly
instantaneous and inductor current can ramp quickly to
maintain output regulation without large bulk output
capacitance. The RT6239A/B is stable with and optimized
for ceramic output capacitors. With internal 30mΩ switches
and 12mΩ synchronous rectifiers, the RT6239A/B displays
excellent efficiency and good behavior across a range of
applications, especially for low output voltages and low
duty cycles. Cycle-by-cycle current limit provides
protection against shorted outputs, input under-voltage
lockout, externally-adjustable soft-start, output under- and
over-voltage protection, and thermal shutdown provide safe
and smooth operation in all operating conditions. The
RT6239A/B is available in the UQFN-14L 2x3 (FC)
package, with exposed thermal pad.
Advanced Constant On-Time (ACOTTM) Control
4.5V to 18V Input Voltage Range
Adjustable Output Voltage from 0.7V to 8V
9A Output Current
30mΩ Internal High-Side N-MOSFET and 12mΩ
Internal Low-Side N-MOSFET
Steady 500kHz Switching Frequency
Up to 95% Efficiency
Optimized for All Ceramic Capacitors
Externally-Adjustable, Pre-Biased Compatible Soft-
Start
Cycle-by-Cycle Current Limit
Input Under-Voltage Lockout
Output Over- and Under-Voltage Protection
Power Good Output
Thermal Shutdown
Applications
Industrial and Commercial Low Power Systems
Computer Peripherals
LCDMonitors and TVs
Green Electronics/Appliances
Point of Load Regulation for High-Performance DSPs,
FPGAs, and ASICs
Simplified Application Circuit
RT6239A/B
V
IN
VIN
SW
V
OUT
BOOT
FB
EN Signal
EN
Power Good
PGOOD
PVCC
SS
GND
Copyright 2016 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
DS6239A/B-04 May 2016
www.richtek.com
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RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
