Datasheet

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VIN

VCON

2.7V to 5.5V

OUT

0.6V to 3.4V

10 PF

4.7 PF

GND

0.47 PH

LM3241

OUT

= 2.5 x VCON

LM3241

www.ti.com

SNOSB38B –JANUARY 2009–REVISED APRIL 2013

LM3241 6MHz, 750mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power

Amplifiers

Check for Samples: LM3241

FEATURES

DESCRIPTION

The LM3241 is a DC-DC converter optimized for

• 6MHz (typ.) PWM Switching Frequency

powering RF power amplifiers (PAs) from a single

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

Lithium-Ion cell; however, it may be used in many

5.5V)

other applications. It steps down an input voltage

• Adjustable Output Voltage (0.6V to 3.4V)

from 2.7V to 5.5V to an adjustable output voltage

from 0.6V to 3.4V. Output voltage is set using a

• 750 mA Maximum Load Capability

VCON analog input for controlling power levels and

• High Efficiency (95% typ. at 3.9V

, 3.3V

OUT

efficiency of the RF PA.

500 mA)

The LM3241 offers three modes of operation. In

• Automatic ECO/PWM mode change

PWM mode the device operates at a fixed frequency

• 6-bump DSBGA Package

of 6MHz (typ.) which minimizes RF interference when

driving medium-to-heavy loads. At light load, the

• Current Overload Protection

device enters into ECO mode automatically and

• Thermal Overload Protection

operates with reduced switching frequency. In ECO

• Soft Start Function

mode, the quiescent current is reduced and extends

• C

and C

OUT

are 0402 (1005) case size and

the battery life. Shutdown mode turns the device off

and reduces battery consumption to 0.1 µA (typ.).

6.3V of rated-voltage ceramic capacitor

• Small Chip Inductor in 0805 (2012) case size

The LM3241 is available in a 6-bump lead-free

DSBGA package. A high-switching frequency (6MHz)

allows use of tiny surface-mount components. Only

APPLICATIONS

three small external surface-mount components, an

• Battery-Powered 3G/4G Power Amplifiers

inductor and two ceramic capacitors are required.

• Hand-Held Radios

• RF PC Cards

• Battery-Powered RF Devices

TYPICAL APPLICATION

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 (23 pages)

PAGE 1
LM3241 www.ti.com SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 LM3241 6MHz, 750mA Miniature, Adjustable, Step-Down DC-DC Converter for RF Power Amplifiers Check for Samples: LM3241 FEATURES DESCRIPTION • • The LM3241 is a DC-DC converter optimized for powering RF power amplifiers (PAs) from a single Lithium-Ion cell; however, it may be used in many other applications. It steps down an input voltage from 2.7V to 5.5V to an adjustable output voltage from 0.6V to 3.4V.
PAGE 2
LM3241 SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure.
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LM3241 www.ti.com SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 ABSOLUTE MAXIMUM RATINGS (1) (2) −0.2V to +6.0V VIN to GND EN, FB, VCON, SW (GND−0.2V) to (VIN+0.2V) w/ 6.
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LM3241 SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 www.ti.com ELECTRICAL CHARACTERISTICS TEST CONDITIONS MIN TYP MAX VFB,MIN Feedback voltage at minimum setting PARAMETER PWM mode, VCON = 0.24V 0.58 0.6 0.62 VFB,MAX Feedback voltage at maximum setting PWM mode, VCON = 1.36V, VIN = 3.9V 3.332 3.4 3.468 ISHDN Shutdown supply current (4) 0.
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LM3241 www.ti.com SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 SYSTEM CHARACTERISTICS The following spec table entries are guaranteed by design providing the component values in the Typical Application Circuit are used. These parameters are not verified by production testing. Min and Max values apply over the full operating ambient temperature range (-30°C ≤ TA ≤ 85°C) and over the VIN range = 2.7V to 5.5V unless otherwise specified. L = 0.47 µH, DCR = 50 mΩ, CIN = 10 µF, 6.3V, 0603 (1608), COUT = 4.
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LM3241 SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 www.ti.com BLOCK DIAGRAM VIN EN ECO COMP OLP Ref1 OVER-VOLTAGE DETECTOR VCON DELAY PWM COMP.
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LM3241 www.ti.com SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 TYPICAL PERFORMANCE CHARACTERISTICS VIN = EN = 3.6V and TA = +25°C, unless otherwise noted. Shutdown Current vs Temperature (SW=VCON=EN=0V) Quiescent Current vs Supply Voltage (No switching, FB=1V, VCON=0V) Figure 1. Figure 2. ECO mode Supply Current vs Output Voltage (Closed loop, Switching, No load) Switching Frequency vs Temperature (VOUT= 2.0V, IOUT=200 mA) Figure 3. Figure 4. Output Voltage vs Supply Voltage (VOUT=2.
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LM3241 SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = EN = 3.6V and TA = +25°C, unless otherwise noted. 0.63 Output Voltage vs Output Current (VOUT=0.6V) 2.03 2.02 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 0.62 ECO to PWM 0.61 0.60 PWM to ECO 0.59 0.58 0 Output Voltage vs Output Current (VOUT=2.0V) ECO to PWM 2.01 2.00 PWM to ECO 1.99 25 50 75 100 125 1.
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LM3241 www.ti.com SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = EN = 3.6V and TA = +25°C, unless otherwise noted. Efficiency vs Output Current (VOUT=2.0V) 100 100 VIN = 3.6V 90 85 VIN = 4.2V 80 75 70 0 90 85 VIN = 3.9V VIN = 4.2V 80 75 100 200 300 400 500 600 700 800 OUTPUT CURRENT(mA) 100 VIN = 3.6V 95 EFFICIENCY (%) EFFICIENCY (%) 95 VIN = 3.0V Efficiency vs Output Current (VOUT=3.
PAGE 10
LM3241 SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = EN = 3.6V and TA = +25°C, unless otherwise noted. 10 VIN-VOUT vs Output Current (100% Duty Cycle) EN High Threshold vs Supply Voltage Figure 19. Figure 20. Output Voltage Ripple in PWM Mode (VOUT=2.0V, IOUT=200 mA) Output Voltage Ripple in ECO Mode (VOUT=2.0V, IOUT=50 mA) Figure 21. Figure 22. VCON Transient Response (VOUT=0.6V/3.4V, RLOAD=10Ω) Line Transient Response (VIN=3.
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LM3241 www.ti.com SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) VIN = EN = 3.6V and TA = +25°C, unless otherwise noted. Load Transient Response (VOUT=2.5V, IOUT=10 mA/250 mA) Load Transient Response (VOUT=0.6V, IOUT=10 mA/60 mA) Figure 25. Figure 26. Startup (VIN=4.2V, VOUT=3.4V, RLOAD=3.6 KΩ) Shutdown (VIN=4.2V, VOUT=3.4V, RLOAD=10 KΩ) Figure 27. Figure 28. Timed Current Limit (VOUT=2.0V, RLOAD=10Ω) Figure 29.
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LM3241 SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 www.ti.com FUNCTIONAL DESCRIPTION Device Information The LM3241 is a simple, step-down DC-DC converter optimized for powering RF power amplifiers (PAs) in mobile phones, portable communicators, and similar battery-powered RF devices. It is designed to allow the RF PA to operate at maximum efficiency over a wide range of power levels from a single Li-Ion battery cell.
PAGE 13
LM3241 www.ti.com SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 ECO Mode Operation At very light loads (50 mA to 100 mA), the LM3241 enters ECO mode operation with reduced switching frequency and supply current to maintain high efficiency. During ECO mode operation, the LM3241 positions the output voltage slightly higher (+7mV typ.) than the normal output voltage during PWM mode operation, allowing additional headroom for voltage drop during a load transient from light to heavy load.
PAGE 14
LM3241 SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 www.ti.com Dynamically Adjustable Output Voltage The LM3241 features dynamically adjustable output voltage to eliminate the need for external feedback resistors. The output can be set from 0.6V to 3.4V by changing the voltage on the analog VCON pin. This feature is useful in PA applications where peak power is needed only when the handset is far away from the base station or when data is being transmitted.
PAGE 15
LM3241 www.ti.com SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 APPLICATION INFORMATION Setting the Output Voltage The LM3241 features a pin-controlled adjustable output voltage to eliminate the need for external feedback resistors. It can be programmed for an output voltage from 0.6V to 3.4V by setting the voltage on the VCON pin, as in the following formula: VOUT = 2.5 x VCON (1) When VCON is between 0.24V and 1.36V, the output voltage will follow proportionally by 2.5 times of VCON.
PAGE 16
LM3241 SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 www.ti.com Capacitor Selection The LM3241 is designed for use with ceramic capacitors for its input and output filters. Use a 10 µF ceramic capacitor for input and a 4.7 µF ceramic capacitor for output. They should maintain at least 50% capacitance at DC bias and temperature conditions. Ceramic capacitors type such as X5R, X7R, and B are recommended for both filters.
PAGE 17
LM3241 www.ti.com SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 Board Layout Considerations PC board layout is an important part of DC-DC converter design. Poor board layout can disrupt the performance of a DC-DC converter and surrounding circuitry by contributing to EMI, ground bounce, and resistive voltage loss in the traces. These can send erroneous signals to the DC-DC converter IC, resulting in poor regulation or instability.
PAGE 18
LM3241 www.ti.com VIN VOUT SNOSB38B – JANUARY 2009 – REVISED APRIL 2013 FB trace on another layer to be protected from noise. 7. Place noise-sensitive circuitry, such as radio IF blocks, away from the DC-DC converter, CMOS digital blocks, and other noisy circuitry. Interference with noise-sensitive circuitry in the system can be reduce through distance.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 24-Apr-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) LM3241TLE/NOPB DSBGA YZR 6 250 178.0 8.4 LM3241TLX/NOPB DSBGA YZR 6 3000 178.0 8.4 Pack Materials-Page 1 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 1.24 1.7 0.76 4.0 8.0 Q1 1.24 1.7 0.76 4.0 8.
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PACKAGE MATERIALS INFORMATION www.ti.com 24-Apr-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM3241TLE/NOPB DSBGA YZR LM3241TLX/NOPB DSBGA YZR 6 250 210.0 185.0 35.0 6 3000 210.0 185.0 35.
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MECHANICAL DATA YZR0006xxx D 0.600±0.075 E TLA06XXX (Rev C) D: Max = 1.51 mm, Min = 1.45 mm E: Max = 1.12 mm, Min = 1.06 mm 4215044/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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