LM2734Z Datasheet, PDF (1/19 Pages) National Semiconductor (TI) – Thin SOT23 1A Load Step-Down DC-DC Regulator

March 2005
LM2734Z
Thin SOT23 1A Load Step-Down DC-DC Regulator
General Description
The LM2734Z regulator is a monolithic, high frequency,
PWM step-down DC/DC converter assembled in a 6-pin Thin
SOT23 and LLP non pull back package. It provides all the
active functions to provide local DC/DC conversion with fast
transient response and accurate regulation in the smallest
possible PCB area.
With a minimum of external components and online design
support through WEBENCH^®™, the LM2734Z is easy to
use. The ability to drive 1A loads with an internal 300mΩ
NMOS switch using state-of-the-art 0.5µm BiCMOS technol-
ogy results 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 3MHz, allowing the use of extremely small
surface mount inductors and chip capacitors. Even though
the operating frequency is very high, efficiencies up to 85%
are easy to achieve. External shutdown is included, featuring
an ultra-low stand-by current of 30nA. The LM2734Z utilizes
current-mode control and internal compensation to provide
high-performance regulation over a wide range of operating
conditions. Additional features include internal soft-start cir-
cuitry to reduce inrush current, pulse-by-pulse current limit,
thermal shutdown, and output over-voltage protection.
Features
n Thin SOT23-6 package, or 6 lead LLP package
n 3.0V to 20V input voltage range
n 0.8V to 18V output voltage range
n 1A output current
n 3MHz switching frequency
n 300mΩ NMOS switch
n 30nA shutdown current
n 0.8V, 2% internal voltage reference
n Internal soft-start
n Current-Mode, PWM operation
n Thermal shutdown
Applications
n DSL Modems
n Local Point of Load Regulation
n Battery Powered Devices
n USB Powered Devices
Typical Application Circuit
Efficiency vs Load Current
V_IN = 5V, V_OUT = 3.3V
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