Datasheet

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LM4671

www.ti.com

SNAS258D –MARCH 2005–REVISED MAY 2013

LM4671 Filterless High Efficiency 2.5W Switching Audio

Amplifier

Check for Samples: LM4671

FEATURES

DESCRIPTION

The LM4671 is a single supply, high efficiency 2.5W

• No Output Filter Required for Inductive Loads

switching audio amplifier. A low noise, filterless PWM

• Externally Configurable Gain

architecture eliminates the output filter, reducing

• Very Fast Turn On Time: 17μs (typ)

external component count, board area consumption,

system cost, and simplifying design.

• Minimum External Components

• "Click and pop" Suppression Circuitry

The LM4671 is designed to meet the demands of

mobile phones and other portable communication

• Micro-Power Shutdown Mode

devices. Operating on a single 5V supply, it is

• Available in Space-Saving DSBGA Package

capable of driving a 4Ω speaker load at a continuous

average output of 2.1W with less than 1% THD+N. Its

APPLICATIONS

flexible power supply requirements allow operation

from 2.4V to 5.5V.

• Mobile Phones

• PDAs

The LM4671 has high efficiency with speaker loads

compared to a typical Class AB amplifier. With a 3V

• Portable Electronic Devices

supply driving an 8Ω speaker, the IC's efficiency for a

100mW power level is 80%, reaching 88% at 400mW

KEY SPECIFICATIONS

output power.

• Efficiency @ 3.6V, 100mW into 8Ω Speaker:

The LM4671 features a low-power consumption

80 % (typ)

shutdown mode. Shutdown may be enabled by

• Efficiency @ 3.6V, 400mW into 8Ω Speaker:

driving the Shutdown pin to a logic low (GND).

88 % (typ)

The gain of the LM4671 is externally configurable

• Efficiency @ 5V, 1W into 8Ω Speaker: 86 %

which allows independent gain control from multiple

(typ)

sources by summing the signals.

• Quiescent Current, 3.6V Supply: 2.8 mA (typ)

• Total Shutdown Power Supply Current: 0.01

µA (typ)

• Single Supply Range: 2.4 to 5.5 V

Typical Application

Figure 1. Typical Audio Amplifier Application Circuit

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 (22 pages)

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LM4671 www.ti.com SNAS258D – MARCH 2005 – REVISED MAY 2013 LM4671 Filterless High Efficiency 2.5W Switching Audio Amplifier Check for Samples: LM4671 FEATURES DESCRIPTION • • • • • • • The LM4671 is a single supply, high efficiency 2.5W switching audio amplifier. A low noise, filterless PWM architecture eliminates the output filter, reducing external component count, board area consumption, system cost, and simplifying design.
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LM4671 SNAS258D – MARCH 2005 – REVISED MAY 2013 www.ti.com Connection Diagram GND IN+ A Vo1 VDD B PGND IN- C Vo2 1 2 SHUTDOWN 3 PVDD Figure 2. 9 Bump DSBGA Package Top View See Package Number YZR0009AAA These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates.
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LM4671 www.ti.com SNAS258D – MARCH 2005 – REVISED MAY 2013 Absolute Maximum Ratings (1) (2) (3) Supply Voltage (1) 6.0V −65°C to +150°C Storage Temperature VDD + 0.3V ≥ V ≥ GND - 0.3V Voltage at Any Input Pin Power Dissipation (4) Internally Limited ESD Susceptibility, all other pins (5) 2.
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LM4671 SNAS258D – MARCH 2005 – REVISED MAY 2013 www.ti.com Electrical Characteristics(1)(2) (continued) The following specifications apply for AV = 2V/V (RI = 150kΩ), RL = 15µH + 8Ω + 15µH unless otherwise specified. Limits apply for TA = 25°C. Symbol IDD Parameter Quiescent Power Supply Current Conditions LM4671 Typical (3) Limit (4) (5) Units (Limits) VIN = 0V, No Load, VDD = 5.0V 6.4 VIN = 0V, No Load, VDD = 3.6V 3.8 6.2 mA (max) mA VIN = 0V, No Load, VDD =2.4V 2.0 3.
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LM4671 www.ti.com SNAS258D – MARCH 2005 – REVISED MAY 2013 Electrical Characteristics(1)(2) (continued) The following specifications apply for AV = 2V/V (RI = 150kΩ), RL = 15µH + 8Ω + 15µH unless otherwise specified. Limits apply for TA = 25°C. Symbol PSRR SNR εOUT Parameter Power Supply Rejection Ratio Conditions LM4671 Typical (3) Limit (4) (5) Units (Limits) VDD = 3.6V, 5V VRipple = 200mVPP Sine, fRipple = 217Hz Inputs to AC GND, CI = 2μF 61.8 dB VDD = 3.
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LM4671 SNAS258D – MARCH 2005 – REVISED MAY 2013 www.ti.com Typical Performance Characteristics 6 THD+N vs Frequency VDD = 2.4V, RL = 15μH+4Ω+15μH, PO = 375mW, 22kHz BW THD+N vs Frequency VDD = 3.6V, RL = 15μH+4Ω+15μH, PO = 750mW, 22kHz BW Figure 3. Figure 4. THD+N vs Frequency VDD = 5V, RL = 15μH+4Ω+15μH, PO = 1.5mW, 22kHz BW THD+N vs Frequency VDD = 2.4V, RL = 15μH+8Ω+15μH, PO = 200mW, 22kHz BW Figure 5. Figure 6. THD+N vs Frequency VDD = 3.
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LM4671 www.ti.com SNAS258D – MARCH 2005 – REVISED MAY 2013 Typical Performance Characteristics (continued) THD+N vs Output Power VDD = 5V, RL = 15μH+4Ω+15μH, f = 1kHz, 22kHz BW THD+N vs Output Power VDD = 5V, RL = 15μH+8Ω+15μH, f = 1kHz, 22kHz BW Figure 9. Figure 10. CMRR vs Frequency VDD = 3.6V, RL = 15μH+8Ω+15μH, Vripple = 1Vp-p, 22kHz BW PSRR vs Frequency VDD = 3.6V, RL = 15μH+8Ω+15μH, Vripple = 200mVp-p, 22kHz BW Figure 11. Figure 12.
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LM4671 SNAS258D – MARCH 2005 – REVISED MAY 2013 www.ti.com Typical Performance Characteristics (continued) 8 Power Dissipation vs Output Power RL = 15μH+4Ω+15μH, f = 1kHz, 22kHz BW Power Dissipation vs Output Power RL = 15μH+8Ω+15μH, f = 1kHz, 22kHz BW Figure 15. Figure 16. Output Power vs Supply Voltage RL = 15μH+4Ω+15μH, VDD = 3.6V Output Power vs Supply Voltage RL = 15μH+8Ω+15μH, VDD = 3.6V Figure 17. Figure 18.
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LM4671 www.ti.com SNAS258D – MARCH 2005 – REVISED MAY 2013 Typical Performance Characteristics (continued) Shutdown Current vs Supply Voltage RL = 15μH+8Ω+15μH Figure 21.
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LM4671 SNAS258D – MARCH 2005 – REVISED MAY 2013 www.ti.com APPLICATION INFORMATION GENERAL AMPLIFIER FUNCTION The LM4671 features a filterless modulation scheme. The differential outputs of the device switch at 300kHz from VDD to GND. When there is no input signal applied, the two outputs (VO1 and VO2) switch with a 50% duty cycle, with both outputs in phase. Because the outputs of the LM4671 are differential, the two signals cancel each other.
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LM4671 www.ti.com SNAS258D – MARCH 2005 – REVISED MAY 2013 The inductive nature of the transducer load can also result in overshoot on one or both edges, clamped by the parasitic diodes to GND and VDD in each case. From an EMI standpoint, this is an aggressive waveform that can radiate or conduct to other components in the system and cause interference. It is essential to keep the power and output traces short and well shielded if possible.
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LM4671 SNAS258D – MARCH 2005 – REVISED MAY 2013 www.ti.com The input capacitors may also be used to remove low audio frequencies. Small speakers cannot reproduce low bass frequencies so filtering may be desired. When the LM4671 is using a single-ended source, power supply noise on the ground is seen as an input signal by the +IN input pin that is capacitor coupled to ground (see Figures 5 -7).
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LM4671 www.ti.com SNAS258D – MARCH 2005 – REVISED MAY 2013 Figure 22. Differential input configuration Figure 23. Differential input configuration with input capacitors Figure 24.
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LM4671 SNAS258D – MARCH 2005 – REVISED MAY 2013 www.ti.com Figure 25. Single-ended input configuration Figure 26.
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LM4671 www.ti.com SNAS258D – MARCH 2005 – REVISED MAY 2013 Figure 27. Dual input with a single-ended input and a differential input REFERENCE DESIGN BOARD SCHEMATIC Figure 28. Reference Design Board Schematic In addition to the minimal parts required for the application circuit, a measurement filter is provided on the evaluation circuit board so that conventional audio measurements can be conveniently made without additional equipment.
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LM4671 SNAS258D – MARCH 2005 – REVISED MAY 2013 www.ti.com The commonly used Audio Precision analyzer is differential, but its ability to accurately reject high frequency signals is questionable necessitating the on board measurement filter. When in doubt or when the signal needs to be single-ended, use an audio signal transformer to convert the differential output to a single ended output.
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LM4671 www.ti.com SNAS258D – MARCH 2005 – REVISED MAY 2013 Figure 32. Internal Layer 1, GND Figure 33. Internal Layer 2, GND Figure 34. Bottom Layer Revision History Rev Date 1.0 03/16/05 Initial release. Description 1.01 12/17/07 Some text edits. 1.02 03/03/08 Edited the SHUTDOWN FUNCTION section (under Application Information).
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-May-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) LM4671ITL/NOPB DSBGA YZR 9 250 178.0 8.4 LM4671ITLX/NOPB DSBGA YZR 9 3000 178.0 8.4 Pack Materials-Page 1 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 1.7 1.7 0.76 4.0 8.0 Q1 1.7 1.7 0.76 4.0 8.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-May-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM4671ITL/NOPB DSBGA YZR LM4671ITLX/NOPB DSBGA YZR 9 250 210.0 185.0 35.0 9 3000 210.0 185.0 35.
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MECHANICAL DATA YZR0009xxx D 0.600±0.075 E TLA09XXX (Rev C) D: Max = 1.542 mm, Min =1.481 mm E: Max = 1.542 mm, Min =1.481 mm 4215046/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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