LM3671 Datasheet, PDF (1/16 Pages) National Semiconductor (TI) – 2MHz , 600mA Step-Down DC-DC Converter in SOT23-5

November 2004
LM3671
2MHz , 600mA Step-Down DC-DC Converter in SOT23-5
General Description
The LM3671 step-down DC-DC converter is optimized for
powering ultra-low voltage circuits from a single Li-Ion cell or
3 cell NiMH/NiCd batteries. It provides up to 600mA load
current, over an input voltage range from 2.8V to 5.5V. There
are several different fixed voltage output options available as
well as an adjustable output voltage version.
The device offers superior features and performance for
mobile phones and similar portable applications with com-
plex power management systems. Automatic intelligent
switching between PWM low-noise and PFM low-current
mode offers improved system control. During full-power op-
eration, a fixed-frequency 2 MHz (typ). PWM mode drives
loads from ∼70 mA to 600 mA max. Hysteretic PFM mode
extends the battery life through reduction of the quiescent
current to 16 µA (typ) at light loads and system standby.
Internal synchronous rectification provides high efficiency. In
shutdown mode (Enable pin pulled low) the device turns off
and reduces battery consumption to 0.01 µA (typ).
The LM3671 is available in a SOT23-5 package with Pb and
No Pb (Lead free) versions. A high switching frequency - 2
MHz (typ) - allows use of tiny surface-mount components.
Only three external surface-mount components, an inductor
and two ceramic capacitors, are required.
n 2 MHz PWM fixed switching frequency (typ)
n Automatic PFM/PWM mode switching
n Available in fixed output voltages and adjustable version
n SOT23-5 package
n Internal synchronous rectification for high efficiency
n Internal soft start
n 0.01 µA typical shutdown current
n Operates from a single Li-Ion cell or 3 cell NiMH/NiCd
batteries
n Only three tiny surface-mount external components
required (one inductor, two ceramic capacitors)
n Current overload and Thermal shutdown protection
Applications
n Mobile phones
n PDAs
n MP3 players
n W-LAN
n Portable instruments
n Digital still cameras
n Portable Hard disk drives
Features
n 16 µA typical quiescent current
n 600 mA maximum load capability
Typical Application Circuits
FIGURE 1. Typical Application Circuit
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