ft2820
4W Dual-PumpTM Class-G Audio Power Amplifier
FEATURES
GENERAL DESCRIPTION
Proprietary Dual-PumpTM topology
The ft2820 is a high efficiency 4W Class-G audio
power amplifier for use in battery-based portable device
applications. It integrates a filterless Class-D audio
power amplifier with a Class-G charge pump regulator
based upon proprietary Dual-PumpTM topology. It
operates from 3.2V to 4.6V supply. When operating
with 4.2V supply voltage, the ft2820 is capable of
delivering into 4Ω load with maximum output power of
4W at 10% THD+N in Non-ALC mode, or a constant
output power of 3.2W at 0.5% THD+N in ALC mode. Its
high efficiency, up to 82%, helps extend battery life.
Filterless Class-D audio amplifier integrated with an
adaptive Class-G charge pump regulator
Automatic level control to eliminate output clipping
Integrated lowpass filter for out-of-band noise
rejection
Maximum output power (Non-ALC Mode)
4.0W (VDD=4.2V, THD+N=10%, RL=4Ω)
3.2W (VDD=3.6V, THD+N=10%, RL=4Ω)
Constant output power (ALC Mode)
3.2W (VDD=4.2V, THD+N=0.5%, RL=4Ω)
2.8W (VDD=3.6V, THD+N=0.5%, RL=4Ω)
In ft2820, the power supply rail for the audio amplifier’s
output stage is internally boosted and regulated at 6V
by an adaptive charge pump regulator based upon the
Dual-PumpTM topology, allowing for a much louder
audio output than a stand-alone one directly connected
to the battery. It makes ft2820 an ideal audio solution
for portable devices that are powered by a single-cell
lithium battery while requiring higher audio loudness.
High efficiency up to 82%
Low THD+N: 0.05%
(VDD=3.6V, f=1kHz, RL=4Ω, Po=1W)
ALC dynamic range: 10.5dB
Low quiescent current: 2.7mA @ VDD=3.6V
High PSRR: 75dB @ 217Hz
Two gain settings: 24.1/27.6dB
The ft2820 features automatic level control (ALC) on
the audio output signals, which detects the output
clipping caused by the over-level input signal and
automatically adjusts the voltage gain of the audio
amplifier to eliminate the clipping while maintaining the
maximally-allowed dynamic range of the audio output
signals.
One-wire pulse control to set operating mode and
voltage gain
Auto-recovering short-circuit protection
Available in TSSOP-20L package
APPLICATIONS
Portable Speakers
Tablets
Mobile Phones
Portable Multimedia Devices
APPLICATION CIRCUIT
VDD
C
CF2 2.2uF
F1 2.2uF
Cs
10uF
CN2
CVDD CP1 CN1 CP2
AVDD
COUT
10uF
PVOUT
Cs
1uF
100uF
PVDD
PGND
VOP
H
ft2820
EN
L
INP
INN
Cin 470nF
Cin 470nF
VON
GND(AGND/CGND)
Figure 1: Typical Application Circuit Diagram
SEP, 2013
www.fangtek.com.cn
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