30.0

1000.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

55.0

FREQUENCY (MHz)

100.0

200.0

300.0

400.0

500.0

600.0

700.0

800.0

900.0

FCC Class B Limit

LM45811 EMI Spectrum

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ÌLM48511

SNAS416H – JULY 2007 – REVISED AUGUST 2015

LM48511 3-W, Ultra-Low EMI, Filterless, Mono, Class D Audio Power Amplifier With

Spread Spectrum

When operating from a 3-V to 4-V power supply, the

1 Features

LM48511 can be configured to drive 1 to 2.5 W into

1

•

3-W Output into 8

Ω at 5 V With THD+N = 1%

an 8-

Ω load with less than 1% distortion (THD+N).

•

Selectable Spread Spectrum Mode Reduces EMI

The Class D amplifier features a low-noise PWM

architecture that eliminates the output filter, reducing

•

80% Efficiency

external component count, board area consumption,

•

Independent Regulator and Amplifier Shutdown

system cost, and simplifying design. A selectable

Controls

spread spectrum modulation scheme suppresses RF

•

Dynamically Selectable Regulator Output Voltages

emissions, further reducing the need for output filters.

•

Filterless Class D

The switching regulator of the LM48511 is a current-

•

3-V to 5.5-V Operation

mode boost converter operating at a fixed frequency

of 1 MHz. Two selectable feedback networks allow

•

Low Shutdown Current

the LM48511 regulator to dynamically switch between

•

Click and Pop Suppression

two different output voltages, improving efficiency by

•

Key Specifications

optimizing the amplifier’s supply voltage based on

battery voltage and output power requirements.

–

Quiescent Power Supply Current

–

The LM48511 is designed for use in portable devices,

such as GPS, mobile phones, and MP3 players. The

–

high, 80% efficiency at 5 V, extends battery life when

–

compared

to

Boosted

Class

AB

amplifiers.

THD+N = 1% 3 W (Typical)

Independent

regulator

and

amplifier

shutdown

–

controls optimize power savings by disabling the

THD+N = 1% 1 W (Typical)

regulator when high-output power is not required.

–

The gain of the LM48511 is set by external resistors,

THD+N = 1% 5.4 W (Typical)

which allows independent gain control from multiple

sources by summing the signals. Output short circuit

–

and thermal overload protection prevent the device

(Typical)

from damage during fault conditions. Superior click

and pop suppression eliminates audible transients

2 Applications

during power-up and shutdown.

•

GPS

Device Information(1)

•

Portable media

PART NUMBER

PACKAGE

BODY SIZE (NOM)

•

Cameras

LM48511

WQFN (24)

5.00 mm × 4.00 mm

•

Mobile Phones

(1) For all available packages, see the orderable addendum at

•

Handheld games

the end of the data sheet.

3 Description

EMI Graph: LM48511 RF Emissions — 3-Inch

The LM48511 device integrates a boost converter

Cable

with a high-efficiency Class D audio power amplifier

to provide 3-W continuous power into an 8-

Ω speaker

when operating from a 5-V power supply.

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.