LM3281 DC-DC Converter Datasheet

LM3281 Datasheet, PDF, Equivalent


Part Number

LM3281

Description

6-MHz Miniature Step-Down DC-DC Converter

Manufacture

etcTI

Total Page 26 Pages
Datasheet
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LM3281
SNVSA38 – NOVEMBER 2014
LM3281 3.3-V, 1.2-A, 6-MHz Miniature Step-Down DC-DC Converter
for Wireless Connectivity Solutions
1 Features
1 Operates from a Single Li-Ion Cell (3 V to 5.5 V)
• 6-MHz (typ.) PWM Switching Frequency
• Fixed Output Voltage: 3.3 V
• Up to 1.2-A Maximum Load Capability
• High Efficiency: 94% (typ.) with 3.8-V VIN at
300 mA
• Analog Bypass: 60-mV (typ.) Drop-Out at 600 mA
• Low IQ: 16 µA typical, 25 µA maximum
• Automatic ECO/PWM/Bypass Mode Change
• Forced PWM Mode for Low Output-Voltage Ripple
• Soft-Start Limits Input Current on Start-Up
• Current Overload Protection
• Thermal Overload Protection
• Small Total Solution Size: < 7.5 mm2
2 Applications
• WLAN, WiFi Station Devices
• WiFi RF PC Cards
• Battery-Powered RF Devices
3 Description
The LM3281 is a high-efficiency low-noise miniature
DC-DC converter optimized for powering noise-
sensitive wireless connectivity chipsets and RF Front
End Modules (FEMs) from a single Lithium-Ion cell.
The LM3281 is ideal for “always on” applications with
very low unloaded quiescent current of 16 µA (typ.).
The LM3281 steps down an input supply voltage to a
fixed output voltage of 3.3 V with output current up to
1200 mA. Five different modes of operation are used
to optimize efficiency and minimize battery drain. In
Pulse Width Modulation (PWM) mode, the device
operates at a fixed frequency of 6 MHz which
minimizes RF interference when driving medium-to-
heavy loads. At light load, the device automatically
enters into Economy (ECO) mode with reduced
quiescent current. In a low-battery voltage condition,
a bypass mode reduces the voltage dropout to 60 mV
(typ.) at 600 mA. If very low output voltage ripple is
desired at light loads, the device can also be forced
into PWM mode. Shutdown mode turns the device off
and reduces battery consumption to 0.1 μA (typ.).
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE
LM3281
DSBGA (6)
1.465 mm x 1.190 (MAX)
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Simplified Schematic
CIN
2.2 µF
VIN
3 V - 5.5 V
VIN
GPO2
GPO1
MODE
SW
LM3281
EN FB
GND
LSW
0.47 µH
COUT
2.2 µF
VOUT
3.3 V
CLOAD2
4.7 µF
CLOAD1
10 µF
VIN_a
VIN_b
VIN_c
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.

LM3281
LM3281
SNVSA38 – NOVEMBER 2014
www.ti.com
Table of Contents
1 Features .................................................................. 1
2 Applications ........................................................... 1
3 Description ............................................................. 1
4 Revision History..................................................... 2
5 Pin Configuration and Functions ......................... 3
6 Specifications......................................................... 4
6.1 Absolute Maximum Ratings ...................................... 4
6.2 Handling Ratings ...................................................... 4
6.3 Recommended Operating Conditions....................... 4
6.4 Thermal Information .................................................. 5
6.5 Electrical Characteristics........................................... 5
6.6 System Characteristics ............................................. 6
6.7 Typical Characteristics .............................................. 7
7 Detailed Description ............................................ 10
7.1 Overview ................................................................. 10
7.2 Functional Block Diagram ....................................... 10
7.3 Feature Description................................................. 10
7.4 Device Functional Modes........................................ 12
8 Application and Implementation ........................ 14
8.1 Application Information............................................ 14
8.2 Typical Application ................................................. 14
9 Power Supply Recommendations...................... 18
10 Layout................................................................... 18
10.1 Layout Guidelines ................................................. 18
10.2 Layout Example .................................................... 19
10.3 DSBGA Package Assembly And Use ................... 19
11 Device and Documentation Support ................. 20
11.1 Device Support .................................................... 20
11.2 Documentation Support ........................................ 20
11.3 Trademarks ........................................................... 20
11.4 Electrostatic Discharge Caution ............................ 20
11.5 Glossary ................................................................ 20
12 Mechanical, Packaging, and Orderable
Information ........................................................... 20
4 Revision History
DATE
November 2014
REVISION
*
NOTES
Initial release.
2 Submit Documentation Feedback
Product Folder Links: LM3281
Copyright © 2014, Texas Instruments Incorporated


Features Product Folder Sample & Buy Technical Documents Tools & Software Support & Community LM3281 SNVSA38 – NOVEMBER 2014 LM3281 3.3-V, 1.2-A, 6-MHz Miniatu re Step-Down DC-DC Converter for Wirele ss Connectivity Solutions 1 Features 1 Operates from a Single Li-Ion Cell (3 V to 5.5 V) • 6-MHz (typ.) PWM Swi tching Frequency • Fixed Output Volta ge: 3.3 V • Up to 1.2-A Maximum Load Capability • High Efficiency: 94% (ty p.) with 3.8-V VIN at 300 mA • Analog Bypass: 60-mV (typ.) Drop-Out at 600 m A • Low IQ: 16 µA typical, 25 µA ma ximum • Automatic ECO/PWM/Bypass Mode Change • Forced PWM Mode for Low Out put-Voltage Ripple • Soft-Start Limit s Input Current on Start-Up • Current Overload Protection • Thermal Overlo ad Protection • Small Total Solution Size: < 7.5 mm2 2 Applications • WLAN , WiFi Station Devices • WiFi RF PC C ards • Battery-Powered RF Devices 3 Description The LM3281 is a high-effici ency low-noise miniature DC-DC converter optimized for powering noisesensitive wireless connectivit.
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