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LM3243

VCON

PGND

SGND

MODE

VBATT

VOUT

ACB

VCC_PA_2G

BB or

RFIC

DAC

GPO2

GPO1

BGND

1.5 µH

10 µF

1.0 µF

4.7 µF

PA(s)

VCC_PA_3G

10 µF

LM3243

www.ti.com

SNVS782B –OCTOBER 2010–REVISED FEBRUARY 2013

LM3243 High-Current Step-Down Converter for 2G/3G/4G RF Power Amplifiers

Check for Samples: LM3243

FEATURES

DESCRIPTION

The LM3243 is a DC-DC converter optimized for

• High-Efficiency PFM and PWM modes with

powering multi-mode 2G/3G/4G RF power amplifiers

Internal Synchronous Rectification

(PAs) from a single Lithium-Ion cell. The LM3243

• Analog Bypass Function with Low Dropout

steps down an input voltage from 2.7V to 5.5V to a

Resistance (45 mΩ typ.)

dynamically adjustable output voltage of 0.4V to 3.6V.

The output voltage is set through a VCON analog

• Dynamically Adjustable Output Voltage, 0.4V

input that adjusts the output voltage to ensure

to 3.6V (typ.), in PFM and PWM Modes

efficient operation at all power levels of the RF PA.

• 2.5A Maximum Load Current in PWM Mode

The LM3243 operates in constant frequency PWM

• 2.7 MHz (average) PWM Switching Frequency

mode producing a small and predictable amount of

• Modulated switching frequency to aid Rx Band

output voltage ripple. This enables best ECTEL

Compliance

power requirements in GMSK and EDGE spectral

• Operates from a Single Li-ion Cell (2.7V to

compliance, with the minimal amount of filtering and

excess headroom. When operating in PFM mode, the

5.5V)

LM3243 enables the lowest DG09 current

• ACB reduces inductor requirements and size

consumption and therefore maximizes system

• Minimum total solution size by using small

efficiency.

footprint and case size inductor and

The LM3243 has a unique Active Current assist and

capacitors

analog Bypass (ACB) feature to minimize inductor

• 16-bump thin DSBGA Package

size without any loss of output regulation for the

• Current and Thermal Overload Protection

entire battery voltage and RF output power range,

until dropout. ACB provides a parallel current path,

when needed, to limit the maximum inductor current

APPLICATIONS

to 1.4A (typ.) while still driving a 2.5A load. The ACB

• Cellular Phones

also enables operation with minimal dropout voltage.

• Hand-Held Radios

The LM3243 is available in a small 2 mm x 2 mm

chip-scale 16-bump DSBGA package.

• RF PC Cards

• Battery-Powered RF Devices

If you are considering using the LM3243 in a system

design, please see the PCB Layout Considerations

section of this data sheet.

TYPICAL SYSTEM APPLICATION DIAGRAM

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (28 pages)

PAGE 1
LM3243 www.ti.com SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 LM3243 High-Current Step-Down Converter for 2G/3G/4G RF Power Amplifiers Check for Samples: LM3243 FEATURES DESCRIPTION • The LM3243 is a DC-DC converter optimized for powering multi-mode 2G/3G/4G RF power amplifiers (PAs) from a single Lithium-Ion cell. The LM3243 steps down an input voltage from 2.7V to 5.5V to a dynamically adjustable output voltage of 0.4V to 3.6V.
PAGE 2
LM3243 SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 www.ti.com Connection Diagram 16-Bump 0.4 mm Pitch Thin DSBGA Package PGND SW PVIN 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 D D FB MODE VCON VDD 1 2 3 4 4 3 2 1 Bottom View Top View PIN DESCRIPTIONS Pin # Name Description PGND Power Ground to the internal NFET switch.
PAGE 3
LM3243 www.ti.com SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 ABSOLUTE MAXIMUM RATINGS (1) (2) (3) VDD, PVIN to SGND −0.2V to +6.0V PGND to SGND −0.2V to +0.2V EN, FB, VCON, BP, MODE (SGND −0.2V) to (VDD +0.2V) SW, ACB (PGND −0.2V) to (PVIN +0.2V −0.2V to +0.
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LM3243 SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 ELECTRICAL CHARACTERISTICS www.ti.com (1) (2) (3) Limits in standard typeface are for TA = TJ = 25°C. Limits in boldface type apply over the full operating ambient temperature range (−30°C ≤ TA = TJ ≤ +90°C). Unless otherwise noted, all specifications apply to the Typical System Application Diagram (page 2) with: PVIN = VDD = EN = 3.8V, BP = 0V.
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LM3243 www.ti.com SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 SYSTEM CHARACTERISTICS The following spec table entries are specified by design and verifications providing the component values in the Typical Application Circuit are used (L = 1.5 µH, DCR = 120 mΩ, TOKO DFE201610C-1R5N, CIN = 10 µF, 6.3V, 0402, Samsung CL05A106MQ5NUN, COUT = 10 µF + 4.7 µF + 3 x 1.0 µF + 3300 pF: 6.3V, 0402, Samsung CL05A106MQ5NUN, CL05A475MQNRN; 6.3V, 0201 Samsung CL03A105MQ3CSN; 6.3V, 01005 Murata GRM022R60J332K).
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LM3243 SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 www.ti.com SYSTEM CHARACTERISTICS (continued) The following spec table entries are specified by design and verifications providing the component values in the Typical Application Circuit are used (L = 1.5 µH, DCR = 120 mΩ, TOKO DFE201610C-1R5N, CIN = 10 µF, 6.3V, 0402, Samsung CL05A106MQ5NUN, COUT = 10 µF + 4.7 µF + 3 x 1.0 µF + 3300 pF: 6.3V, 0402, Samsung CL05A106MQ5NUN, CL05A475MQNRN; 6.3V, 0201 Samsung CL03A105MQ3CSN; 6.
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LM3243 www.ti.com SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs. Load Current VIN = 3.8V, IOUT = 150mA to 750mA 100 100 95 95 90 90 EFFICENCY (%) EFFICIENCY (%) Efficiency vs. Load Current VIN = 3.8V, IOUT = 10mA to 150mA 85 80 75 VOUT = 1.0V VOUT = 1.5V VOUT = 2.0V VOUT = 2.5V VOUT = 3.0V 70 65 85 80 75 VOUT = 1.6V VOUT = 2.0V VOUT = 2.5V VOUT = 3.0V VOUT = 3.5V 70 65 60 60 0 20 40 60 80 100 120 140 160 LOAD CURRENT (mA) Figure 1.
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LM3243 SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) Quiescent Current (PFM) vs. Supply Voltage VOUT = 1V, 2.7V < VIN< 5.5V (No Load) 290 2.95 QUIESCENT CURRENT ( A) SWITCHING FREQUENCY (MHz) Center-Switching Frequency vs. Supply Voltage VOUT = 2.5V, IOUT = 700mA, VIN = 3.8V 3.00 2.90 2.85 2.80 2.75 2.70 2.65 2.60 2.55 2.50 3.0 270 260 250 240 230 220 210 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) Figure 7. 6.0 2.5 Quiescent Current (PWM) vs.
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LM3243 www.ti.com SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN Load Transient in PWM Mode = 3.8V, VOUT = 2.5V, IOUT = 0mA to 300mA VOUT 20 mV/ DIV IOUT 200 mA/ DIV Load Transient in PWM Mode VIN = 3.8V, VOUT = 3.0V, IOUT = 0mA to 700mA VOUT 50 mV/ DIV IOUT 500 mA/ DIV 100 Ps/DIV 100 Ps/DIV Figure 13. Figure 14. Load Transient in PWM Mode VIN = 4.2V, VOUT = 3.0V, IOUT = 0mA to 1.2A Line Transient VIN = 3.6V to 4.2V, VOUT = 2.
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LM3243 SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN Startup in PWM Mode = 4.2V, VOUT = 3.4V, No Load, EN = LOW to HIGH Timed-Current Limit VIN = 4.2V, VOUT = 2.5V, RLOAD = 6.8Ω to VOUT Shorted VOUT 2V/DIV VSW 2V/DIV 2V/DIV VSW 2V/DIV Inductor Current 1A/DIV VOUT 2V/DIV EN 20 s/DIV 40 s/DIV Figure 19. 10 Figure 20.
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LM3243 www.ti.com SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 FUNCTIONAL DESCRIPTION Device Information The LM3243 is a high-efficiency step-down DC-DC converter optimized to power the RF power amplifier (PA) in cell phones, portable communication devices, or battery-powered RF devices with a single Li-Ion battery.
PAGE 12
LM3243 SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 www.ti.com PFM Mode With MODE = HIGH, the LM3243 automatically transitions to from PWM into PFM (Pulse Frequency Modulation) operation if the average inductor current is less than 75 mA (typ.) and VIN − VOUT > 0.6V. The switcher regulates the fixed output voltage by transferring a fixed amount of energy during each cycle and modulating the frequency to control the total power delivered to the output.
PAGE 13
LM3243 www.ti.com SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 Dynamic Adjustment of Output Voltage The output voltage of the LM3243 can be dynamically adjusted by changing the voltage on the VCON pin. In RF PA applications, peak power is required when the handset is far away from the base station. To maximize the power savings, the LM3243 output should be set just high enough to achieve the desired PA linearity.
PAGE 14
LM3243 SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 www.ti.com APPLICATION INFORMATION Setting the Output Voltage DAC Control An analog voltage to the VCON pin can dynamically program the output voltage from 0.4V (typ.) to 3.6V (typ.) in both PFM and PWM modes of operation, without the need for external resistors. The output voltage is governed by Table 2. Table 2. Output Voltage Selection VCON (V) VOUT (V) VCON = 0.16V to 1.44V 2.5 x VCON VIN 10 µF PVIN VDD 1.
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LM3243 www.ti.com SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 EN VCON VCON = 0.4V 8 30 Ps 8 30 Ps VOUT 3.4V 3.4V 3.4V 1V 0V 1.7A 7 20 Ps 7 20 Ps 7 20 Ps ILOAD < 200 mA 7 20 Ps 0A Figure 22. Dynamic Adjustment of Output Voltage with GPIO VCON Pin Figure 23 shows the equivalent CRC circuit for the VCON pin. This circuit is internal to the part and should be taken into consideration when driving this pin. R1 = 100 k: C1 = 1.7 pF C2 = 9 pF Figure 23.
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LM3243 SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 www.ti.com Table 3. Suggested Inductors and Their Suppliers Vendor Size ISAT −30% DCR DFE201610C-1R5M (1285AS-H-1R5M) TOKO 2.0 mm x 1.6 mm x 1.0 mm 2.2A 120 mΩ PSD20161T-1R5MS CYNTEC 2.0 mm x 1.6 mm x 1.0 mm 1.6A 143 mΩ TDK 2.0 mm x 1.6 mm x 1.0 mm 2.2A 140 mΩ Model TFM201610-1R5M Capacitor Selection The LM3243 is designed to use ceramic capacitors for its input and output filters.
PAGE 17
LM3243 www.ti.com SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 VIN EN VCON BP 8 30 µs VOUT 7 20 µs Figure 24. Startup Sequence and Conditions DSBGA Package Assembly And Use Use of the DSBGA package requires specialized board layout, precision mounting and careful re-flow techniques, as detailed in Texas Instruments Application Note AN-1112. Please refer to the section Surface Mount Assembly Considerations.
PAGE 18
LM3243 SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 www.ti.com PCB LAYOUT CONSIDERATIONS Overview PC board layout is critical to successfully designing a DC-DC converter into a product. A properly planned board layout optimizes the performance of a DC-DC converter and minimizes effects on surrounding circuitry while also addressing manufacturing issues that can have adverse impacts on board quality and final product yield.
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LM3243 www.ti.com To • • • • • SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 help minimize noise coupled back into power supplies: Use a star connection to route from the VBATT power input to Switcher PVIN and to VBATT_PA. Route traces for minimum inductance between supply pins and bypass capacitor(s). Route traces to minimize inductance between bypass capacitors and the ground plane. Maximize power supply trace inductance(s) to reduce coupling among function blocks.
PAGE 20
LM3243 SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 www.ti.com Figure 26. Top View of RF Evaluation Board with PAs DC-DC Converter Section Figure 27.
PAGE 21
LM3243 www.ti.com SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 Figure 28. Board Layer 2 - FB, VDD, Additional Routing for PGND, PVIN Figure 29.
PAGE 22
LM3243 SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 www.ti.com Figure 30. Board Layer 4 - GND Plane VCC_PA Figure 31.
PAGE 23
LM3243 www.ti.com SNVS782B – OCTOBER 2010 – REVISED FEBRUARY 2013 VBATT Star Supply Connection Figure 32. Multiple Board Layers - VBATT Supply Star Connection VBATT Star Connection: It is critically important to use a ‘Star’ connection from VBATT supply to LM3243 PVIN and from VBATT to PA modules as implementing a ‘daisy chain’ supply connection may add noise to the PA output.
PAGE 24
PACKAGE OPTION ADDENDUM www.ti.
PAGE 25
PACKAGE MATERIALS INFORMATION www.ti.com 23-Dec-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device LM3243TME/NOPB Package Package Pins Type Drawing SPQ DSBGA 250 YFQ 16 Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 178.0 8.4 Pack Materials-Page 1 2.08 B0 (mm) K0 (mm) P1 (mm) 2.08 0.76 4.0 W Pin1 (mm) Quadrant 8.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Dec-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM3243TME/NOPB DSBGA YFQ 16 250 210.0 185.0 35.
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MECHANICAL DATA YFQ0016xxx D 0.600±0.075 E TMD16XXX (Rev A) D: Max = 2.049 mm, Min =1.989 mm E: Max = 2.049 mm, Min =1.989 mm 4215081/A NOTES: A. All linear dimensions are in millimeters. Dimensioning and tolerancing per ASME Y14.5M-1994. B. This drawing is subject to change without notice. www.ti.
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