LM27341_10 Datasheet, PDF (1/30 Pages) National Semiconductor (TI) – 2 MHz 1.5A/2A Wide Input Range Step-Down DC-DC Regulator with Frequency Synchronization

LM27341/LM27342/
LM27341Q/LM27342Q
February 9, 2010
2 MHz 1.5A/2A Wide Input Range Step-Down DC-DC
Regulator with Frequency Synchronization
General Description
The LM27341 and LM27342 regulators are monolithic, high
frequency, PWM step-down DC-DC converters in 10-pin LLP
and 10-pin eMSOP packages. They contain all the active
functions to provide local DC-DC conversion with fast tran-
sient response and accurate regulation in the smallest possi-
ble PCB area.
With a minimum of external components the LM27341 and
LM27342 are easy to use. The ability to drive 1.5A or 2A loads
respectively, with an internal 150 mΩ NMOS switch results in
the best power density available. The world-class control cir-
cuitry allows for on-times as low as 65 ns, thus supporting
exceptionally high frequency conversion. Switching frequen-
cy is internally set to 2 MHz and synchronizable from 1 to 2.35
MHz, which allows the use of extremely small surface mount
inductors and chip capacitors. Even though the operating fre-
quency is very high, efficiencies up to 90% are easy to
achieve. External shutdown is included featuring an ultra-low
shutdown current of 70 nA. The LM27341and LM27342 utilize
peak current-mode control and internal compensation to pro-
vide high-performance regulation over a wide range of oper-
ating conditions. Additional features include internal soft-start
circuitry to reduce inrush current, pulse-by-pulse current limit,
thermal shutdown, and output over-voltage protection.
Features
■ ^{Space saving 3 x 3 mm LLP-10 & eMSOP-10 package}
■ ^{Wide input voltage range}
3V to 20V
■ ^{Wide output voltage range 1V to 18V}
■ ^{LM27341 delivers 1.5A maximum output current}
■ ^{LM27342 delivers 2A maximum output current}
■ ^{High switching frequency}
2 MHz
■ ^{Frequency synchronization}
2.35 MHz
1.00 MHz < f_SW <
■ ^{150 mΩ NMOS switch with internal bootstrap supply}
■ ^{70 nA shutdown current}
■ ^{Internal voltage reference accuracy of 1%}
■ ^{Peak Current-Mode, PWM operation}
■ ^{Thermal shutdown}
■ ^{LM27341Q and LM27342Q are AEC-Q100 Grade 1}
qualified and are manufactured on an Automotive Grade
Flow
Applications
■ ^{Local 12V to Vcore Step-Down Converters}
■ ^{Radio Power Supply}
■ ^{Core Power in HDDs}
■ ^{Set-Top Boxes}
■ ^Automotive
■ ^{USB Powered Devices}
■ ^{DSL Modems}
Typical Application Circuit
30005674
© 2010 National Semiconductor Corporation 300056
30005676
Efficiency vs Load Current
V_OUT = 5V, f_sw = 2 MHz
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