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.