LM3676 Datasheet, PDF (1/20 Pages) National Semiconductor (TI) – 2MHz, 600mA Step-Down DC-DC Converter with Mode Control

December 2006
LM3676 2MHz, 600mA Step-Down DC-DC Converter with
Mode Control
General Description
The LM3676 step-down DC-DC converter is optimized for
powering low voltage circuits from a single Li-Ion cell battery
and input voltage rails from 2.9V 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.
The LM3676 has a mode-control pin that allows the user to
select continuous Forced PWM mode over the complete load
range or an intelligent PFM-PWM mode that changes modes
depending on the load. PWM mode offers superior efficiency
under high load conditions (>100mA) and the lowest output
noise performance. In Auto mode, PFM-PWM, hysteretic
PFM extends the battery life through reduction of the quies-
cent current to 16µA (typ.) during light loads and system
standby.
The LM3676 is available in a 8-lead non-pullback LLP pack-
age in leaded (PB) and lead-free (NO PB) versions. A high
switching frequency of 2 MHz (typ) allows use of tiny surface-
mount components, an inductor and two ceramic capacitors.
Features
■ ^{16 µA typical quiescent current}
■ ^{600 mA maximum load capability}
■ ^{2 MHz PWM fixed switching frequency (typ)}
■ ^{Automatic PFM/PWM mode switching or Forced PWM}
mode
■ ^{Available in fixed output voltages and adjustable version}
■ ^{8-Lead non-pullback LLP package}
■ ^{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}
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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