LM3743_08 Datasheet, PDF (1/28 Pages) National Semiconductor (TI) – High-Performance Synchronous Buck Controller with Comprehensive Fault Protection Features

October 7, 2008
LM3743
High-Performance Synchronous Buck Controller with
Comprehensive Fault Protection Features
General Description
The LM3743 is a DC-DC voltage mode PWM buck controller
featuring synchronous rectification at 300 kHz or 1 MHz. It can
deliver current as high as 20A and step down from an input
voltage between 3V and 5.5V down to a minimum output volt-
age of 0.8V, with a ±1.75% internal reference accuracy. The
LM3743 provides a set of comprehensive fault protection fea-
tures such as high-side current limit, output under-voltage
protection, and low-side current limit. When any of these fault
protection features are engaged, it enters a hiccup protection
mode which is suitable for high reliability systems such as
rack mounted servers and telecom base station subsystems.
The LM3743 also employs a proprietary monolithic glitch free
pre-bias start-up method suited for FPGA and ASIC logic de-
vices. An external programmable soft-start allows for tracking
and timing flexibility. The driver features 1.6Ω of pull-up re-
sistance and 1Ω of pull-down drive resistance for high power
density and very efficient power processing.
Features
■ ^{Input voltage from 3.0V to 5.5V}
■ ^{Output voltage adjustable down to 0.8V}
■ ^{Reference accuracy: ±1.75%, over full temperature and}
input voltage range
■ ^{High-side and Low-side N-Channel MOSFETs}
■ ^{Switching frequency options of 1 MHz or 300 kHz}
■ ^{Comprehensive Fault Protection Features:}
High-side current limit
Low-side current limit
Output under-voltage protection
■ ^{Hiccup mode protection eliminates thermal runaway}
during fault conditions
■ ^{Externally programmable soft-start with tracking capability}
■ ^{Pre-bias start-up capability}
■ ^{MSOP-10 package}
Applications
■ ^{Rack-mount servers}
■ ^{Telecom base stations}
■ ^Routers
■ ^{Printers/Scanners}
■ ^{Multi-media set-top boxes}
■ ^{FPGAs, ASICs, and DSPs}
Typical Application
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