LM48511

Manufacturer Part NumberLM48511
ManufacturerTexas Instruments
LM48511 datasheet
 


Specifications of LM48511

Speaker ChannelsMonoSpeaker Amp TypeClass-D, Class-D Boosted
Output Power(w)6.7Psrr(db)88
Supply Min(min)(volt)3Supply Max(max)(volt)5.5
Pin/package24QFN, 24WQFN  
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3W, Ultra-Low EMI, Filterless, Mono, Class D Audio Power
Amplifier with Spread Spectrum
General Description
The LM48511 integrates a boost converter with a high effi-
ciency Class D audio power amplifier to provide 3W continu-
ous power into an 8Ω speaker when operating from a 5V
power supply. When operating from a 3V to 4V power supply,
the LM48511 can be configured to drive 1 to 2.5W into an
8Ω load with less than 1% distortion (THD+N). The Class D
amplifier features a low noise PWM architecture that elimi-
nates the output filter, reducing external component count,
board area consumption, system cost, and simplifying design.
A selectable spread spectrum modulation scheme suppress-
es RF emissions, further reducing the need for output filters.
The LM48511’s switching regulator is a current-mode boost
converter operating at a fixed frequency of 1MHz. Two se-
lectable feedback networks allow the LM48511 regulator to
dynamically switch between two different output voltages, im-
proving efficiency by optimizing the amplifier’s supply voltage
based on battery voltage and output power requirements.
The LM48511 is designed for use in portable devices, such
as GPS, mobile phones, and MP3 players. The high, 80%
efficiency at 5V, extends battery life when compared to Boost-
ed Class AB amplifiers. Independent regulator and amplifier
shutdown controls optimize power savings by disabling the
regulator when high output power is not required.
The gain of the LM48511 is set by external resistors, which
allows independent gain control from multiple sources by
summing the signals. Output short circuit and thermal over-
load protection prevent the device from damage during fault
conditions. Superior click and pop suppression eliminates au-
dible transients during power-up and shutdown.
EMI Graph
Boomer
®
is a registered trademark of National Semiconductor Corporation.
© 2012 Texas Instruments Incorporated
LM48511
Key Specifications
■ 
Quiescent Power Supply Current
V
DD
V
DD
■ 
P
at V
O
= 8Ω, THD+N = 1%
R
L
■ 
P
at V
O
= 8Ω, THD+N = 1%
R
L
■ 
P
at V
O
= 4Ω, THD+N = 1%
R
L
■ 
Shutdown Current at V
Features
3W Output into 8Ω at 5V with THD+N = 1%
Selectable spread spectrum mode reduces EMI
80% Efficiency
Independent Regulator and Amplifier Shutdown Controls
Dynamically Selectable Regulator Output Voltages
Filterless Class D
3.0V – 5.5V operation
Low Shutdown Current
Click and Pop Suppression
Applications
GPS
Portable media
Cameras
Mobile Phones
Handheld games
FIGURE 1. LM48511 RF Emissions — 3 inch cable
300222 SNAS416D
February 28, 2012
= 3V
= 5V
13.5mA (typ)
= 5V, PV1 = 7.8V
DD
= 3V, PV1 = 4.8V
DD
= 5V, PV1 = 7.8V
DD
0.01μA (typ)
= 3V
DD
300222h5
9mA (typ)
3.0W (typ)
1W (typ)
5.4W (typ)
www.ti.com

LM48511 Summary of contents

  • Page 1

    ... When operating from power supply, the LM48511 can be configured to drive 1 to 2.5W into an 8Ω load with less than 1% distortion (THD+N). The Class D amplifier features a low noise PWM architecture that elimi- nates the output filter, reducing external component count, board area consumption, system cost, and simplifying design ...

  • Page 2

    ... Typical Application FIGURE 2. Typical LM48511 Audio Amplifier Application Circuit www.ti.com 2 300222i3 ...

  • Page 3

    ... Connection Diagrams SQ Package Top View Order Number LM48511SQ See NS Package Number SQA24B SQ Package Marking 300222d5 Top View U — Wafer fab code Z — Assembly plant XY — 2 Digit date code TT — Lot traceability 3 300222d4 www.ti.com ...

  • Page 4

    Pin Descriptions LLP-24 Pin 1 2 22,23 24 DAP www.ti.com Name Regulator Feedback Select. Connect to VDD to select feedback FB_SEL network ...

  • Page 5

    ... 4Ω 3W 1kHz ≤ ≤ −40° MAX ≤ ≤ 4. Note 10) = 2V/ 25.5kΩ 4.87kΩ LM48511 Typical Limit (Note 6) (Note 7) 13.5 14.5 22 0.11 1 1.03 1.4 0.92 0.4 49 0.01 3 3.0 2.6 3.0 3.8 3.8 5.4 5.4 6.7 6.7 0.03 0.03 0.04 0.05 150°C 3.8°C/W 32.8°C/W ≤ +85°C A ≤ ...

  • Page 6

    ... C SS Note 12 6 LM48511 Typical Limit (Note 6) (Note 217Hz 73 80 1.23 Note 10) = 2V/ 25.5kΩ 5.36kΩ LM48511 Typical Limit (Note 6) (Note 7) 16 17.5 26.6 0.03 1 0.96 1.4 0.84 0.4 50 0.04 Units (Limits) µV RMS µV RMS µV RMS µV RMS ...

  • Page 7

    ... RIPPLE P 217Hz RIPPLE = 200mV Sine, RIPPLE P 1kHz RIPPLE = 200mV Sine, RIPPLE P 10kHz RIPPLE = 217Hz RIPPLE P-P RIPPLE = 8Ω 1kHz LM48511 Units (Limits) Typical Limit (Note 6) (Note 7) 2.5 W 2.5 W 3.0 W 3.0 W 4.3 W 4.2 W 5.4 W 5.3 W 0.03 % 0.03 % 0.04 % 0.05 % µV 35 RMS 36 µV RMS µV ...

  • Page 8

    ... 500mW 1kHz 500mW 1kHz 20Hz to 20kHz Inputs to AC GND, No weighting 20Hz to 20kHz Inputs to AC GND, A weighted Note 10) = 2V/ 25.5kΩ 9.31kΩ LM48511 Typical Limit (Note 6) (Note 7) 9 9.5 0.01 1 0.91 0.79 49 0.04 1 0.84 1 1.3 1.3 1.8 1.8 2.2 2.2 = 8Ω L 0.02 0.03 = 4Ω ...

  • Page 9

    ... RIPPLE P-P RIPPLE = 8Ω 1kHz θ the number given in Absolute Maximum Ratings, whichever is lower. For the LM48511, see power +25ºC, and at the Recommended Operation Conditions at the time of product A — (no load LM48511 Typical Limit ...

  • Page 10

    Typical Performance Characteristics THD+N vs Frequency 2W, filter = 22kHz THD+N vs Frequency 1.5W, filter = 22kHz THD+N vs Output ...

  • Page 11

    THD+N vs Output Power = 8Ω 3V, 3.6V, 5V 1kHz, filter = 22kHz 4.87kΩ 300222i1 Boost Amplifier vs Output Power = 8Ω 5V ...

  • Page 12

    PSRR vs Frequency V = 3.6V 200mV RIPPLE PP Supply Current vs Supply Voltage PV = 7.8V 1 Supply Current vs Supply Voltage PV = 4.8V 1 www.ti.com = 8Ω ...

  • Page 13

    Power Dissipation vs Output Power = 8Ω 3.6V 7V 300222f8 Boost Converter Efficiency vs I LOAD( 300222h8 Boost Converter Efficiency vs I LOAD(DC) ...

  • Page 14

    ... AUDIO AMPLIFIER POWER DISSIPATION AND EFFICIENCY The major benefit of a Class D amplifier is increased efficiency versus a Class AB. The efficiency of the LM48511 is attributed to the region of operation of the transistors in the output stage. www.ti.com The Class D output stage acts as current steering switches, consuming negligible amounts of power compared to their Class AB counterparts ...

  • Page 15

    ... PV1, V1 and V as close to the device as possible. AUDIO AMPLIFIER GAIN SETTING RESISTOR SELECTION The amplifier gain of the LM48511 is set by four external re- sistors, the input resistors, R5 and R7, and the feed back resistors R6 and R8.. The amplifier gain is given by: Where R is the input resistor and R is the feedback resistor ...

  • Page 16

    ... Where “I ” is the peak inductor current. The LM48511 will limit P its switch current based on peak current. With I creasing L will increase the maximum amount of power avail- able to the load. Conversely, using too little inductance may limit the amount of load current which can be drawn from the output. Best performance is usually obtained when the con- verter is operated in “ ...

  • Page 17

    ... I FEED-FORWARD COMPENSATION FOR BOOST SW CONVERTER Although the LM48511 regulator is internally compensated, an external feed-forward capacitor, (C1) may be required for stability (Figure 1). The compensation capacitor places a zero in regulator loop response. The recommended frequency of the zero ( 22.2kHz. The value given by: Z π ...

  • Page 18

    Revision History Rev Date 1.0 07/24/07 1.1 07/25/07 1.2 09/25/07 1.3 11/06/07 1.4 02/25/08 1.5 02/28/12 www.ti.com Initial released. Input some text edits. Changed the Amplifier Voltage (Operating Ratings section) from 5.0V to 4.8V. = 4Ω) section in the Key ...

  • Page 19

    ... Physical Dimensions inches (millimeters) unless otherwise noted SQ Package Order Number LM48511SQ NS Package Number SQA24B 19 www.ti.com ...

  • Page 20

    Notes ...

  • Page 21

    ... Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’ ...