TECHNICAL INFORMATION
B
External Components Description
(Refer to the Application/Test Circuit)
Components
R
I
R
F
C
I
R
REF
C
A
C
D
C
P
Description
Inverting input resistance to provide AC gain in conjunction with R
F
. This input is
biased at the BIASCAP voltage (approximately 2.4VDC).
Feedback resistor to set AC gain in conjunction with R
I
;
A
V
=
12(R
F
/ R
I
)
. Please refer
to the Amplifier Gain paragraph, in the Application Information section.
AC input coupling capacitor which, in conjunction with R
I
, forms a highpass filter at
f
C
=
1 ( 2
π
R
I
C
I
)
C
S
C
SW
C
Z
R
Z
D
O
L
O
Bias resistor. Locate close to pin 4 and ground at pin 7.
BIASCAP decoupling capacitor. Should be located close to pin 14 and grounded at
pin 7.
Charge pump input capacitor. This capacitor should be connected directly between
pins 31 and 32 and located physically close to the TA2020-020.
Charge pump output capacitor that enables efficient high side gate drive for the
internal H-bridges. To maximize performance, this capacitor should be connected
directly between pin 29 (CPUMP) and pin 27 (VDDA). Please observe the polarity
shown in the Application/Test Circuit.
Supply decoupling for the low current power supply pins. For optimum performance,
these components should be located close to the pin and returned to their
respective ground as shown in the Application/Test Circuit.
Supply decoupling for the high current H-Bridge supply pins. These components
must be located as close to the device as possible to minimize supply overshoot and
maximize device reliability. Both the high frequency bypassing (0.1uF) and bulk
capacitor (180uF) should have good high frequency performance including low ESR
and low ESL. Panasonic HFQ or FC capacitors are ideal for the bulk capacitor.
Zobel capacitor, which in conjunction with R
Z
, terminates the output filter at high
frequencies
Zobel resistor, which in conjunction with C
Z
, terminates the output filter at high
frequencies. The combination of R
Z
and C
Z
minimizes peaking of the output filter
under both no load conditions or with real world loads, including loudspeakers which
usually exhibit a rising impedance with increasing frequency. Depending on the
program material, the power rating of R
Z
may need to be adjusted. The typical value
is �½ watt.
Schottky diodes that minimize undershoots of the outputs with respect to power
ground during switching transitions. For maximum effectiveness, these diodes must
be located close to the output pins and returned to their respective PGND. Please
see Application/Test Circuit for ground return pin.
Output inductor, which in conjunction with C
O
, demodulates (filters) the switching
waveform into an audio signal. Forms a second order filter with a cutoff frequency
of and a quality factor of
Q
=
R
L
C
O
L
O
C
O
.
Output capacitor which in conjunction with L
O
, demodulates (filters) the switching
waveform into an audio signal. Forms a second order low-pass filter with a cutoff
frequency of
f
C
=
1 ( 2
π
L
O
C
O
)
and a quality factor of
Q
=
R
L
C
O
L
O
C
O
.
Common mode capacitor.
C
O
C
CM
6 of 13
TA2020-020, Rev. 4.0, 09.00
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
