|
LM27341 Datasheet, PDF (1/30 Pages) National Semiconductor (TI) – 2 MHz 1.5A/2A Wide Input Range Step-Down DC-DC Regulator with Frequency Synchronization | |||
|
December 16, 2008
LM27341/LM27342
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 m⦠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
â Space saving 3 X 3 mm LLP-10 & eMSOP-10 package
â Wide input voltage range
3 to 20 V
â Wide output voltage range
1 to 18 V
â LM27341 delivers 1.5A maximum output current
â LM27342 delivers 2A maximum output current
â High switching frequency
2 MHz
â Frequency synchronization 1.00 MHz < fSW < 2.35 MHz
â 150 m⦠NMOS switch with internal bootstrap supply
â 70 nA shutdown current
â Internal voltage reference accuracy of 1%
â Peak Current-Mode, PWM operation
â Thermal shutdown
Applications
â Local 12V to Vcore Step-Down Converters
â Radio Power Supply
â Core Power in HDDs
â Set-Top Boxes
â Automotive
â USB Powered Devices
â DSL Modems
Typical Application Circuit
30005674
30005676
Efficiency vs Load Current
VOUT = 5V, fsw = 2 MHz
© 2008 National Semiconductor Corporation 300056
www.national.com
|
▷ |