TCA2002 Datasheet, PDF (9/18 Pages) Tripath Technology Inc. – STEREO CLASS-T™ AUDIO CONTROLLER USING DIGITAL POWER PROCESSING (DPP™) TECHNOLOGY

Tripath Technology, Inc. - Technical Information
Amplifier Gain
The gain of an amplifier based on the TCA2002 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 for the various
amplifier configurations.
A = A * A VTK2150
VINPUTSTAG E
V MODULATOR
For example, using a TCA2002 with the following external components, in a Single Ended, Split
Supply Application
R_I = 20kΩ
R_F = 30.1kΩ
R_FBA = 1kΩ
R_FBB = 1.1kΩ
R_FBC = 10.0kΩ
AVTCA2002 ≈ − ^{20k Ω}  ^{10.0k Ω * (1.0k Ω + 1.1k Ω )} + 1 = - 13.35 ^V
30.1k Ω _
1.0k Ω *1.1k Ω

V
Input Stage Design
The TCA2002 input stage is configured as an inverting amplifier, allowing the system designer
flexibility in setting the input stage gain and frequency response. Figure 2 shows a typical application
where the input stage is a constant gain inverting amplifier. The input stage gain should be set so
that the maximum input signal level will drive the input stage output to 4Vpp.
INPUT1
RF
CI
RI
TCA2002
OAOUT1
V5
INV1
-
+
BIASCAP
AGND
V5
INPUT2
RF
CI
RI
INV2
OAOUT2
+
-
AGND
Figure 2: Input Stage
The gain of the input stage, above the low frequency high pass filter point, is that of a simple inverting
amplifier: It should be noted that the input amplifiers are biased at approximately 2.5VDC. Thus, the
polarity of C_I must be followed as shown in Figure 2 for a standard ground referenced input signal
A V INPUT STAGE = − ^{R F}
RI
9
TCA2002 – KLi/0.95/04.06