LM2738 Datasheet, PDF (1/28 Pages) National Semiconductor (TI) – 550kHz/1.6MHz 1.5A Step-Down DC-DC Switching Regulator

April 10, 2008
LM2738
550kHz/1.6MHz 1.5A Step-Down DC-DC Switching
Regulator
General Description
The LM2738 regulator is a monolithic, high frequency, PWM
step-down DC/DC converter in an 8-pin LLP or 8-pin eMSOP
package. It provides all the active functions for local DC/DC
conversion with fast transient response and accurate regula-
tion in the smallest possible PCB area.
With a minimum of external components, the LM2738 is easy
to use. The ability to drive 1.5A loads with an internal
250mΩ NMOS switch using state-of-the-art 0.5µm BiCMOS
technology results in the best power density available.
Switching frequency is internally set to 550kHz (LM2738Y) or
1.6MHz (LM2738X), allowing the use of extremely small sur-
face mount inductors and chip capacitors. Even though the
operating frequencies are very high, efficiencies up to 90%
are easy to achieve. External enable is included, featuring an
ultra-low stand-by current of 400nA. The LM2738 utilizes cur-
rent-mode control and internal compensation to provide high-
performance regulation over a wide range of operating
conditions. Additional features include internal soft-start cir-
cuitry to reduce in-rush current, cycle-by-cycle current limit,
thermal shutdown, and output over-voltage protection.
Features
■ ^{Space Saving LLP-8 and eMSOP-8 package}
■ ^{3.0V to 20V input voltage range}
■ ^{0.8V to 18V output voltage range}
■ ^{1.5A output current}
■ ^{550kHz (LM2738Y) and 1.6MHz (LM2738X)}
switching frequencies
■ ^{250mΩ NMOS switch}
■ ^{400nA shutdown current}
■ ^{0.8V, 2% internal voltage reference}
■ ^{Internal soft-start}
■ ^{Current-Mode, PWM operation}
■ ^{Thermal shutdown}
Applications
■ ^{Local Point of Load Regulation}
■ ^{Core Power in HDDs}
■ ^{Set-Top Boxes}
■ ^{Battery Powered Devices}
■ ^{USB Powered Devices}
■ ^{DSL Modems}
Typical Application Circuit
Efficiency vs Load Current
V_IN = 12V, V_OUT = 3.3V
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