LM2734 Thin SOT23 1A Load Step-Down DC-DC Regulator
October 2004
LM2734
Thin SOT23 1A Load Step-Down DC-DC Regulator
General Description
The LM2734 regulator is a monolithic, high frequency, PWM
step-down DC/DC converter in a 6-pin Thin SOT23 package.
It provides all the active functions to provide local DC/DC
conversion with fast transient response and accurate regu-
lation in the smallest possible PCB area.
With a minimum of external components and online design
support through WEBENCH
™
, the LM2734 is easy to use.
The ability to drive 1A loads with an internal 300mΩ NMOS
switch using state-of-the-art 0.5µm BiCMOS technology re-
sults in the best power density available. The world class
control circuitry allows for on-times as low as 13ns, thus
supporting exceptionally high frequency conversion over the
entire 3V to 20V input operating range down to the minimum
output voltage of 0.8V. Switching frequency is internally set
to 550kHz (LM2734Y) or 1.6MHz (LM2734X), allowing the
use of extremely small surface mount inductors and chip
capacitors. Even though the operating frequencies are very
high, efficiencies up to 90% are easy to achieve. External
shutdown is included, featuring an ultra-low stand-by current
of 30nA. The LM2734 utilizes current-mode control and in-
ternal compensation to provide high-performance regulation
over a wide range of operating conditions. Additional fea-
tures include internal soft-start circuitry to reduce inrush
current, pulse-by-pulse current limit, thermal shutdown, and
output over-voltage protection.
Features
n
n
n
n
n
n
n
n
n
n
n
Thin SOT23-6 package
3.0V to 20V input voltage range
0.8V to 18V output voltage range
1A output current
550kHz (LM2734Y) and 1.6MHz (LM2734X)
switching frequencies
300mΩ NMOS switch
30nA shutdown current
0.8V, 2% internal voltage reference
Internal soft-start
Current-Mode, PWM operation
WEBENCH online design tool
Applications
n
n
n
n
n
n
n
Local Point of Load Regulation
Core Power in HDDs
Set-Top Boxes
Battery Powered Devices
USB Powered Devices
DSL Modems
Notebook Computers
Typical Application Circuit
Efficiency vs Load Current
V
IN
= 5V, V
OUT
= 3.3V
20102301
20102345
WEBENCH
™
is a trademark of Transim.
© 2004 National Semiconductor Corporation
DS201023
www.national.com
NSC [ NATIONAL SEMICONDUCTOR ]
