LM3671_07 Datasheet, PDF (1/24 Pages) National Semiconductor (TI) – 2MHz, 600mA Step-Down DC-DC Converter

November 29, 2007
LM3671
2MHz, 600mA Step-Down DC-DC Converter
General Description
The LM3671 step-down DC-DC converter is optimized for
powering low voltage circuits from a single Li-Ion cell battery
and input voltage rails from 2.7V to 5.5V. It provides up to
600mA load current, over the entire input voltage range.
There are several different fixed voltage output options avail-
able as well as an adjustable output voltage version range
from 1.1V to 3.3V.
The device offers superior features and performance for mo-
bile phones and similar portable systems. Automatic intelli-
gent switching between PWM low-noise and PFM low-current
mode offers improved system control. During PWM mode, the
device operates at a fixed-frequency of 2 MHz (typ). Hys-
teretic PFM mode extends the battery life by reducing the
quiescent current to 16 µA (typ) during light load and standby
operation. Internal synchronous rectification provides high ef-
ficiency during PWM mode operation. In shutdown mode, the
device turns off and reduces battery consumption to 0.01 µA
(typ).
The LM3671 is available in SOT23-5, tiny 5-bump micro SMD
and a 6-pin LLP packages in leaded (PB) and lead-free (NO
PB) versions. A high switching frequency of 2 MHz (typ) al-
lows use of tiny surface-mount components. Only three ex-
ternal surface-mount components, an inductor and two
ceramic capacitors, are required.
Features
■ ^{16 µA typical quiescent current}
■ ^{600 mA maximum load capability}
■ ^{2 MHz PWM fixed switching frequency (typ)}
■ ^{Automatic PFM/PWM mode switching}
■ ^{Internal synchronous rectification for high efficiency}
■ ^{Internal soft start}
■ ^{0.01 µA typical shutdown current}
■ ^{Operates from a single Li-Ion cell battery}
■ ^{Only three tiny surface-mount external components}
required (one inductor, two ceramic capacitors)
■ ^{Current overload and Thermal shutdown protection}
■ ^{Available in fixed output voltages and adjustable version}
■ ^{SOT23-5, 5-bump micro SMD and 6-pin LLP packages}
Applications
■ ^{Mobile phones}
■ ^PDAs
■ ^{MP3 players}
■ ^W-LAN
■ ^{Portable instruments}
■ ^{Digital still cameras}
■ ^{Portable Hard disk drives}
Typical Application Circuits
FIGURE 1. Typical Application Circuit
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