DC-DC Converter. LM3243 Datasheet

LM3243 Converter. Datasheet pdf. Equivalent

LM3243 Datasheet
Recommendation LM3243 Datasheet
Part LM3243
Description Step-Down DC-DC Converter
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Texas Instruments LM3243
Product
Folder
Sample &
Buy
Technical
Documents
Tools &
Software
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LM3243
SNVS782C – OCTOBER 2010 – REVISED AUGUST 2015
LM3243 High-Current Step-Down Converter for 2G, 3G, and 4G RF Power Amplifiers
1 Features
1 Input Voltage Range: 2.7 V to 5.5 V
• High-Efficiency PFM and PWM Modes With
Internal Synchronous Rectification
• Analog Bypass Function with Low Dropout
Resistance (45 mTypical)
• Dynamically Adjustable Output Voltage: 0.4 V to
3.6 V (Typical) in PFM and PWM Modes
• Maximum Load Current: 2.5 A in PWM Mode
• PWM Switching Frequency: 2.7 MHz (Average)
• Modulated Switching Frequency to Aid Rx Band
Compliance
• Operates From a Single Li-ion Cell
(2.7 V to 5.5 V)
• Current and Thermal Overload Protection
• ACB Reduces Inductor Requirements and Size
• Minimum Total Solution Size by Using Small
Footprint and Case Size Inductor and Capacitors
2 Applications
• Cellular Phones
• Hand-Held Radios
• RF PC Cards
• Battery-Powered RF Devices
3 Description
The LM3243 is a DC-DC converter optimized for
powering multi-mode 2G, 3G, and 4G RF power
amplifiers (PAs) from a single Lithium-Ion cell. The
LM3243 steps down an input voltage from 2.7 V to
5.5 V to a dynamically adjustable output voltage of
0.4 V to 3.6 V. The output voltage is set through a
VCON analog input that adjusts the output voltage to
ensure efficient operation at all power levels of the
RF PA.
The LM3243 operates in constant frequency PWM
mode producing a small and predictable amount of
output voltage ripple. This enables best ECTEL
power requirements in GMSK and EDGE spectral
compliance, with the minimal amount of filtering and
excess headroom. When operating in PFM mode, the
LM3243 enables the lowest DG09 current
consumption and therefore maximizes system
efficiency.
The LM3243 has a unique Active Current assist and
analog Bypass (ACB) feature to minimize inductor
size without any loss of output regulation for the
entire battery voltage and RF output power range,
until dropout. ACB provides a parallel current path,
when needed, to limit the maximum inductor current
to 1.4 A (typical) while still driving a 2.5-A load. The
ACB also enables operation with minimal dropout
voltage. When considering using the LM3243 in a
system design, see the Layout section of this data
sheet.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (MAX)
LM3243
DSBGA (16)
2.049 mm × 2.049 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
VBATT
10 µF
GPO1
GPO2
DAC
BB or
RFIC
Typical System Application Diagram
EN
BP
MODE
PVIN VDD
LM3243
SW
FB
ACB
VCON PGND SGND BGND
1.5 µH
VOUT
10 µF
VCC_PA_3G
1.0 µF
VCC_PA_2G
4.7 µF
PA(s)
PA
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.



Texas Instruments LM3243
LM3243
SNVS782C – OCTOBER 2010 – REVISED AUGUST 2015
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 .................................................. 5
6.5 Electrical Characteristics .......................................... 5
6.6 System Characteristics ............................................ 6
6.7 Timing Requirements ................................................ 7
6.8 Typical Characteristics .............................................. 8
7 Detailed Description ............................................ 11
7.1 Overview ................................................................. 11
7.2 Functional Block Diagram ....................................... 12
7.3 Feature Description................................................. 12
7.4 Device Functional Modes........................................ 13
8 Application and Implementation ........................ 15
8.1 Application Information............................................ 15
8.2 Typical Application ................................................. 15
9 Power Supply Recommendations...................... 19
10 Layout................................................................... 20
10.1 Layout Guidelines ................................................. 20
10.2 Layout Example .................................................... 21
10.3 DSBGA Package Assembly and Use ................... 25
11 Device and Documentation Support ................. 26
11.1 Device Support...................................................... 26
11.2 Documentation Support ........................................ 26
11.3 Community Resources.......................................... 26
11.4 Trademarks ........................................................... 26
11.5 Electrostatic Discharge Caution ............................ 26
11.6 Glossary ................................................................ 26
12 Mechanical, Packaging, and Orderable
Information ........................................................... 26
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision B (February 2013) to Revision C
Page
• Added Device Information and Pin Configuration and Functions sections, ESD Rating table, Feature Description,
Device Functional Modes, Application and Implementation, Power Supply Recommendations, Layout, Device and
Documentation Support, and Mechanical, Packaging, and Orderable Information sections ................................................. 1
2 Submit Documentation Feedback
Product Folder Links: LM3243
Copyright © 2010–2015, Texas Instruments Incorporated



Texas Instruments LM3243
www.ti.com
5 Pin Configuration and Functions
LM3243
SNVS782C – OCTOBER 2010 – REVISED AUGUST 2015
PGND
SW
PVIN
TMD Package
16-Pin DSBGA
ACB A A ACB
PVIN
SW PGND
PGND
SW
PVIN
ACB B B
ACB
PVIN
SW PGND
SGND
EN
BP
BGND C C
BGND
BP
EN SGND
VDD
VCON MODE
FB
DD
FB
MODE VCON
VDD
12 34
Top View
4321
Bottom View
Pin Functions
PIN
NO. NAME
TYPE
DESCRIPTION
A1
PGND
Ground Power ground to the internal NFET switch.
B1
C1
SGND
Ground Signal analog and control ground (low current).
D1
VDD
Power Analog supply input.
A2 Switching node connection to the internal PFET switch and NFET synchronous rectifier. Connect
B2
SW Analog to an inductor with a saturation current rating that exceeds the ILIM,PFET,Steady State current limit
specification of the LM3243.
C2
EN
Digital/Input
Enable input. Set this digital input HIGH for normal operation. For shutdown, set low. Pin has an
800-kinternal pulldown resistor.
D2
VCON
Analog Voltage control analog input. VOUT = 2.5 × VCON.
A3
PVIN
Power Power supply voltage input to the internal PFET switch and ACB.
B3
C3
BP
Digital
Bypass mode input. Set the pin HIGH for forced Bypass mode operation. Set the pin LOW for
automatic analog bypass mode (recommended).
D3
MODE
Digital/Input
PWM/PFM mode selection input. Setting the pin HIGH allows for PFM or PWM, depending on
the load current. Setting the pin LOW forces the part to be in PWM only.
A4
ACB
Output Analog Current Bypass (ACB). Connect to the output at the output filter capacitor.
B4
C4
BGND
Ground ACB ground (high current).
D4 FB Analog Feedback analog input. Connect to the output at the output filter capacitor.
Copyright © 2010–2015, Texas Instruments Incorporated
Product Folder Links: LM3243
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