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DC-DC Converter. LM3241 Datasheet |
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LM3241
SNOSB38C – JANUARY 2009 – REVISED NOVEMBER 2017
LM3241 6-MHz, 750-mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power
Amplifiers
1 Features
•1 6-MHz (typ.) PWM Switching Frequency
• Operates from a Single Li-Ion Cell (2.7 V to 5.5 V)
• Adjustable Output Voltage (0.6 V to 3.4 V)
• 750-mA Maximum Load Capability
• High Efficiency (95% typ. at 3.9 VIN, 3.3 VOUT at
500 mA)
• Automatic Eco-mode™ and PWM Mode Change
• 6-Bump DSBGA Package
• Current Overload Protection
• Thermal Overload Protection
• Soft Start Function
• CIN and COUT are 0402 (1005) Case Size and 6.3
V of Rated-Voltage Ceramic Capacitor
• Small Chip Inductor in 0805 (2012) Case Size
2 Applications
• Battery-Powered 3G and 4G Power Amplifiers
• Hand-Held Radios
• RF PC Cards
• Battery-Powered RF Devices
3 Description
The LM3241 is a DC-DC converter optimized for
powering RF power amplifiers (PAs) from a single
Lithium-Ion cell. The device can also be used in many
other applications. The device steps down an input
voltage from 2.7 V to 5.5 V to an adjustable output
voltage from 0.6 V to 3.4 V. The output voltage is set
using a VCON analog input for controlling power
levels and efficiency of the RF PA.
The LM3241 offers three modes of operation. In
PWM mode the device operates at a fixed frequency
of 6 MHz (typical) which minimizes RF interference
when driving medium-to-heavy loads. At light-load
conditions, the device enters into Eco-mode
automatically and operates with reduced switching
frequency. In Eco-mode, the quiescent current is
reduced and extends the battery life. Shutdown mode
turns the device off and reduces battery consumption
to 0.1 µA (typical).
The LM3241 is available in a 6-bump lead-free
DSBGA package. A high-switching frequency (6
MHz) allows use of tiny surface-mount components.
Only three small external surface-mount components,
an inductor and two ceramic capacitors are required.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
LM3241
DSBGA (6)
1.50 mm × 1.30 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
VIN
2.7 V to 5.5 V
Typical Application
10 F
VIN
EN
VCON
LM3241
GND
0.47 µH
SW
FB
VOUT
0.6 V to 3.4 V
VOUT = 2.5 × VCON
4.7 F
Copyright © 2017, Texas Instruments Incorporated
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.
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LM3241
SNOSB38C – JANUARY 2009 – REVISED NOVEMBER 2017
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 ESD Ratings.............................................................. 4
6.3 Recommended Operating Conditions....................... 4
6.4 Thermal Information .................................................. 4
6.5 Electrical Characteristics........................................... 5
6.6 System Characteristics ............................................. 6
6.7 Typical Characteristics .............................................. 7
7 Detailed Description ............................................ 12
7.1 Overview ................................................................. 12
7.2 Functional Block Diagram ....................................... 13
7.3 Feature Description................................................. 13
7.4 Device Functional Modes........................................ 15
8 Application and Implementation ........................ 16
8.1 Application Information............................................ 16
8.2 Typical Application ................................................. 16
9 Power Supply Recommendations...................... 19
10 Layout................................................................... 19
10.1 Layout Guidelines ................................................. 19
10.2 Layout Example .................................................... 21
11 Device and Documentation Support ................. 22
11.1 Documentation Support ........................................ 22
11.2 Receiving Notification of Documentation Updates 22
11.3 Community Resources.......................................... 22
11.4 Trademarks ........................................................... 22
11.5 Electrostatic Discharge Caution ............................ 22
11.6 Glossary ................................................................ 22
12 Mechanical, Packaging, and Orderable
Information ........................................................... 22
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision B (April 2013) to Revision C
Page
• Added the Device Information table, ESD Ratings table, Feature Description section, Device Functional Modes
section, Application and Implementation section, Power Supply Recommendations section, Layout section, Device
and Documentation Support section, and Mechanical, Packaging, and Orderable Information section ............................... 1
• Deleted the maximum lead temperature parameter from the Absolute Maximum Ratings table........................................... 4
• Changed the minimum TJ and TA from –30°C to –40°C in the Recommended Operating Conditions table ......................... 4
• Added the Thermal Information table ..................................................................................................................................... 4
• Added maximum values for VOUT step rise and fall times under –40°C to 85°C TA range in the System
Characteristics table ............................................................................................................................................................... 6
• Added maximum value for turnon time under –40°C to 85°C TA range in the System Characteristics table ........................ 6
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Product Folder Links: LM3241
Copyright © 2009–2017, Texas Instruments Incorporated
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5 Pin Configuration and Functions
LM3241
SNOSB38C – JANUARY 2009 – REVISED NOVEMBER 2017
YZR Package With 0.5 mm Pitch
6-Pin DSBGA
Top View
12
A EN VIN
B VCON SW
C FB GND
Not to scale
Pin Functions
PIN
NO. NAME
TYPE
DESCRIPTION
A1
EN
I
Enable Input. Set this digital input high for normal operation. For shutdown, set low. Do not
leave EN pin floating.
A2
VIN
PWR
Power supply input. Connect to the input filter capacitor (see Figure 29).
B1
VCON
I
Voltage Control Analog input. VCON controls VOUT in PWM mode. Do not leave VCON pin
floating. VOUT = 2.5 × VCON.
Switching Node connection to the internal PFET switch and NFET synchronous rectifier.
B2
SW
PWR
Connect to an inductor with a saturation current rating that exceeds the maximum Switch
Peak Current Limit specification of the LM3241.
C1 FB I Feedback Analog Input. Connect to the output at the output inductor.
C2
GND
— Ground
Copyright © 2009–2017, Texas Instruments Incorporated
Product Folder Links: LM3241
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