1 Features

1• 3-W Output into 8 Ω at 5 V 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-V to 5.5-V Operation

• Low shutdown current

• Click and pop suppression

• Key specifications

– Quiescent power supply current

– VDD = 3 V 9 mA (Typical)

– VDD = 5 V 13.5 mA (Typical)

– PO at VDD = 5 V, PV1 = 7.8 V, RL = 8 Ω,

THD+N = 1% 3 W (Typical)

– PO at VDD = 3 V, PV1 = 4.8 V, RL = 8 Ω,

THD+N = 1% 1 W (Typical)

– PO at VDD = 5 V, PV1 = 7.8 V, RL = 4 Ω,

THD+N = 1% 5.4 W (Typical)

– Shutdown Current at VDD = 3 V, 0.01 μA

(Typical)

2 Applications

• GPS

• Portable media

• Cameras

• Mobile phones

• Handheld games

3 Description

The LM48511 device integrates a boost converter

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.

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

LM48511 can be configured to drive 1 to 2.5 W into

an 8-Ω load with less than 1% distortion (THD+N).

The Class D amplifier features a low-noise PWM

architecture that eliminates the output filter, reducing

external component count, board area consumption,

system cost, and simplifying design. A selectable

spread spectrum modulation scheme suppresses RF

emissions, further reducing the need for output filters.

The switching regulator of the LM48511 is a currentmode

boost converter operating at a fixed frequency

of 1 MHz. Two selectable feedback networks allow

the LM48511 regulator to dynamically switch between

two different output voltages, improving 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 5 V, extends battery life when

compared to Boosted 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 overload protection prevent the device

from damage during fault conditions. Superior click

and pop suppression eliminates audible transients

during power-up and shutdown.