apa2058 Anpec Electronics Corporation, apa2058 Datasheet - Page 23

• Manufacturer Part Number: apa2058
• Description: 2.4w Stereo Fully Differential Audio Power Amplifier With Stereo Class Ab Cap-free Headphone Driver And Ldo
• Manufacturer: Anpec Electronics Corporation

APA2058
Application Information
Windows Vista
Input Capacitor (C
In the typical application, an input capacitor, C
to allow the amplifier to bias the input signal to the proper
DC level for optimum operation. In this case, C
minimum input impedance R
the corner frequency is determined in the following
equation:
The value of C
directly affects the low frequency performance of the circuit.
Consider the example where R
cation calls for a flat bass response down to 40Hz. The
equation is reconfigured as below :
Consider the variation of input resistance (R
of C
from 0.22 F to 1.0 F would be chosen. A further consid-
eration for this capacitor is the leakage path from the in-
put source through the input network (R
load.
This leakage current creates a DC offset voltage at the
input to the amplifier that reduces useful headroom, es-
pecially in high gain applications. For this reason, a low-
Copyright
Rev. A.5 - Feb., 2010
Analog Line Output Jack
(R
Analog Headphone Output
Jack
(R
Analog Headphone Output
Jack
(R
L
L
L
=10k )
=320 )
=32 )
C
f
i
C(highpass
should be 0.2 F. Therefore, a value in the range
i
Device Type
2
1
R
)
ANPEC Electronics Corp.
i
f
i
c
TM
must be considered carefully because it
2
Premium Mobile Requirement
i
)
R
1
i
C
i
i
form a high-pass filter with
Full Scale Output voltage
THD+N
Line output cross-talk
Noise level during system
activity
Full Scale Output voltage
THD+N
Headphone output cross-talk
Noise level during system
activity
Full Scale Output voltage
THD+N
Headphone output cross-talk
Noise level during system
activity
i
is 20k
Requirement
i
and the specifi-
+ R
i
i
, is required
), the value
f
, C
i
and the
i
) to the
(1)
(2)
23
The optimum decoupling is achieved by using two differ-
ent types of capacitors that target on different types of
noise on the power supply leads. For higher frequency
transients, spikes, or digital hash on the line, a good low
equivalent-series- resistance (ESR) ceramic capacitor,
(0.1 F typically) placed as close as possible to the device
VDD lead works best.
For filtering lower frequency noise signals, a large alumi-
num electrolytic capacitor of 10 F or greater placed near
the audio power amplifier is recommended.
Power Supply Decoupling Capacitor, C
The APA2058 is a high-performance CMOS audio ampli-
fier that requires adequate power supply decoupling to
ensure the output total harmonic distortion (THD) to be
as low as possible. Power supply decoupling also pre-
vents the oscillations being caused by long lead length
between the amplifier and the speaker.
leakage tantalum or ceramic capacitor is the best choice.
When polarized capacitors are used, the positive side of
the capacitors should face the amplifiers’ inputs in most
applications because the DC level of the amplifiers’ in-
puts are held at V
confirm the capacitor polarity in the application.
0.707V
-65dBFS
-50dB,
-80dBFS
0.707V
-65dBFS
-50 dB
-80dBFS
0.3V
-45dBFS
-50dB
-80dBFS
100Hz~20kHz
20Hz~20kHz
20Hz~15kHz
A-weighting
100Hz~15kHz
100Hz~20kHz
100Hz~15kHz
A-weighting
A-weighting
rms
rms
rms
Value
DD
/2. Please note that it is important to
2.3V
-70dB
-70dB
-100dBFS A-weighting
2.3V
-78dB
-75 dB
-100dBFS
2.0V
-68dB
-70 dB
-100dBFS A-weighting
APA2058 typical performance
20Hz~20kHz
20Hz~20kHz
100Hz~20kHz
100Hz~15kHz
A-weighting
100Hz~20kHz
100Hz~15kHz
rms
rms
rms
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