DC-DC Regulator. LM27342 Datasheet


LM27342 Regulator. Datasheet pdf. Equivalent


LM27342


2 MHz 1.5A/2A Wide Input Range Step-Down DC-DC Regulator
LM27341/LM27342 2 MHz 1.5/2A Wide Input Range Step-Down DC-DC Regulator with Frequency Synchronization

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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 transient response and accurate regulation in the smallest possible 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 circuitry allows for on-times as low as 65 ns, thus supporting exceptionally high frequency conversion. Switching frequency 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 frequency 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 provide high-performance regulation over a wide range of opera...



LM27342
December 16, 2008
www.DataSheet4U.com
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 mNMOS 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
3 to 20 V
Wide output voltage range
1 to 18 V
LM27341 delivers 1.5A maximum output current
LM27342 delivers 2A maximum output current
High switching frequency
2 MHz
Frequency synchronization 1.00 MHz < fSW < 2.35 MHz
150 mNMOS switch with internal bootstrap supply
70 nA shutdown current
Internal voltage reference accuracy of 1%
Peak Current-Mode, PWM operation
Thermal shutdown
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
30005676
Efficiency vs Load Current
VOUT = 5V, fsw = 2 MHz
© 2008 National Semiconductor Corporation 300056
www.national.com

LM27342
Connection Diagrams
Top View
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Top View
10 - Lead LLP
30005604
10 - Lead eMSOP
30005605
Ordering Information
Order Number
LM27341MY
LM27341MYX
LM27342MY
LM27342MYX
LM27341SD
LM27341SDX
LM27342SD
LM27342SDX
Package Type
eMSOP -10
eMSOP -10
eMSOP -10
eMSOP -10
LLP - 10
LLP - 10
LLP - 10
LLP - 10
NSC Package Drawing
MUC10A
MUC10A
MUC10A
MUC10A
SDA10A
SDA10A
SDA10A
SDA10A
Pin Descriptions
Package Marking
SSCB
SSCB
SSCA
SSCA
L231B
L231B
L231A
L231A
Transport Media
1000 Units on Tape and Reel
3500 Units on Tape and Reel
1000 Units on Tape and Reel
3500 Units on Tape and Reel
1000 Units on Tape and Reel
4500 Units on Tape and Reel
1000 Units on Tape and Reel
4500 Units on Tape and Reel
Pin
1,2
3
4
5
6
7
8
9,10
DAP
Name
SW
BOOST
EN
SYNC
FB
GND
AVIN
PVIN
GND
Function
Output switch. Connects to the inductor, catch diode, and bootstrap capacitor.
Boost voltage that drives the internal NMOS control switch. A bootstrap capacitor is connected between
the BOOST and SW pins.
Enable control input. Logic high enables operation. Do not allow this pin to float or be greater than VIN
+ 0.3V.
Frequency synchronization input. Drive this pin with an external clock or pulse train. Ground it to use
the internal clock.
Feedback pin. Connect FB to the external resistor divider to set output voltage.
Signal and Power Ground pin. Place the bottom resistor of the feedback network as close as possible
to this pin for accurate regulation.
Supply voltage for the control circuitry.
Supply voltage for output power stage. Connect a bypass capacitor to this pin.
Signal / Power Ground and thermal connection. Tie this directly to GND (pin 7). See Application
Information regarding optimum thermal layout.
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