Tripath Technology, Inc. - Technical Information
Node 1
24V
RBIAS1
4.64KΩ
RFBC1
9.1KΩ
6
2
+
CBYPASS
0.1uF
CBYPASS
10.0uF
RFBB1
1.0KΩ
RBIAS2
54.9KΩ
TC2001
RFBC2
9.1KΩ
RFBB2
1.0KΩ
Figure 1: Modulator Feedback Bias Resistors
The equivalent formula to calculate RBIAS1 is:
1
BIAS1
1
1
BIAS2
=
+
R
R
FB
R
Where RFB is:
1
1
1
=
+
R
FB
R
FBC1 + RFBB1
R
FBC2 + RFBB2
T K2019 Amp lifier Gain
The gain of the TK2019 is the product of the input stage gain and the modulator gain. Please refer to
the sections, Input Stage Design, and Modulator Feedback Design, for a complete explanation of how
to determine the external component values.
A
V TK2019 = AV INPUT STAGE * A
V MODULATOR
R
R
F
I
R
FBC + R FBB
A
V TK2019
≈
R
FBB
For example, using a TK2019 with the following external components,
RI = 20kΩ
RF = 20kΩ
RFBB = 1kΩ
RFBC = 9.1kΩ
20k Ω 9.1k Ω + 1kΩ
V
V
A
V TK2019
≈
≈ 10
20k Ω
1kΩ
Please note that Output 1 and Output 2, as shown in the Application/Test Diagram, are out of phase
with respect to the input signal. This phase reversal can be eliminated by connecting the negative
terminals of the speakers to Output 1 and Output 2 and the positive speaker terminals to ground.
13
TK2019 – MC/2.1/10-03
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
