LM3487 Datasheet, PDF (1/22 Pages) National Semiconductor (TI) – High Efficiency High-Side N-Channel Controller for Switching Regulator

February 19, 2008
LM3487
High Efficiency High-Side N-Channel Controller for
Switching Regulator
General Description
The LM3487 is a high-side N-channel MOSFET switching
regulator controller. It can be used in topologies requiring a
high side MOSFET such as buck, inverting (buck-boost) and
zeta regulators. The LM3487's internal push pull driver allows
compatibility with a wide range of MOSFETs. A wide input
voltage range and an adjustable current limit allow the
LM3487 to be optimized for a wide variety of applications.
The LM3487 has an adjustable switching frequency which
can also be synchronized to an external clock. Current-mode
control requires only a single resistor and capacitor for fre-
quency compensation. The current mode architecture also
yields superior line and load regulation and cycle-by-cycle
current limiting. A 7µA shutdown state can be used for power
savings and for power supply sequencing. Other features in-
clude external soft-start to reduce inrush current and output
over voltage protection.
Features
■ ^{Adjustable/synchronizable switching frequency from}
100kHz to 1.4MHz
■ ^{Adjustable cycle by cycle current limit}
■ ^{Wide 3V-35V input voltage range}
■ ^{Thermal shutdown}
■ ^{Frequency compensation optimized with a single}
capacitor and resistor
■ ^{External softstart}
■ ^{Current mode operation}
■ ^{Undervoltage lockout with hysteresis}
■ ^{10-lead Mini-SO10 (MSOP-10) package}
■ ^{Automotive grade including AEC-Q100 is available}
Applications
■ ^{ADSL Modems}
■ ^{Local Voltage Regulation}
■ ^{Distributed Power}
■ ^{Notebook and Palmtop Computers}
■ ^{Internet Appliances}
■ ^{Printers and Office Automation}
■ ^{Battery operated Devices}
■ ^{Cable Modems}
■ ^{Battery Chargers}
Typical Application Circuit
Typical High Efficiency Step-Down (Buck) Converter
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