Datasheet
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APPLICATION INFORMATION
20 19 18 17 16
6 7 8 9 10
1
2
3
4
5 11
12
13
14
15
VDD
GND
CPP
CPM
CPVSS
SD
SDA
SCL
GND
GND
LEFTINM
LEFTINP
GND
RIGHTINP
RIGHTINM
CPVSS
HPLEFT
GND
VDD
HPRIGHT
VDD
1 Fm
1 Fm
SCL
SDA
SD
0.47 Fm
0.47 Fm
0.47 Fm
0.47 Fm
1 Fm 1 Fm
VDD
TPA6130A2
Headphone Amplifiers
f
c
+
1
2pR
L
C
O
(1)
C
O
+
1
2pR
L
f
c
(2)
TPA6130A2
SLOS488B – NOVEMBER 2006 – REVISED FEBRUARY 2008
SIMPLIFIED APPLICATIONS CIRCUIT
Single-supply headphone amplifiers typically require dc-blocking capacitors. The capacitors are required because
most headphone amplifiers have a dc bias on the outputs pin. If the dc bias is not removed, the output signal is
severely clipped, and large amounts of dc current rush through the headphones, potentially damaging them. The
top drawing in Figure 36 illustrates the conventional headphone amplifier connection to the headphone jack and
output signal.
DC blocking capacitors are often large in value. The headphone speakers (typical resistive values of 16 Ω or 32
Ω ) combine with the dc blocking capacitors to form a high-pass filter. Equation 1 shows the relationship between
the load impedance (R
L
), the capacitor (C
O
), and the cutoff frequency (f
C
).
C
O
can be determined using Equation 2 , where the load impedance and the cutoff frequency are known.
If f
c
is low, the capacitor must then have a large value because the load resistance is small. Large capacitance
values require large package sizes. Large package sizes consume PCB area, stand high above the PCB,
increase cost of assembly, and can reduce the fidelity of the audio output signal.
Two different headphone amplifier applications are available that allow for the removal of the output dc blocking
capacitors. The Capless amplifier architecture is implemented in the same manner as the conventional amplifier
with the exception of the headphone jack shield pin. This amplifier provides a reference voltage, which is
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