Tripath Technology, Inc. - Technical Information
For the power section, Tripath has traditionally used a “star” grounding scheme. Thus, the load
ground returns and the power supply decoupling traces are routed separately back to the power
supply. In addition, any type of shield or chassis connection would be connected directly to the
ground star located at the power supply. These precautions will both minimize audible noise and
enhance the crosstalk performance of the TA2022.
The TA2022 incorporates a differential feedback system to minimize the effects of ground bounce
and cancel out common mode ground noise. As such, the feedback from the output ground for each
channel needs to be properly sensed. This can be accomplished by connecting the output ground
“sensing” trace directly to the star formed by the output ground return, output capacitor, CO, and the
zobel capacitor, CZ. Refer to the Application / Test Circuit for a schematic description.
Pin 3, VN10GND, is used for the VN10 buck converter. Pin 3 can be connected to the main power
supply decoupling ground trace (or plane) without any loss in functionality or reduction of
performance. This pin is electrically shorted to the copper heat sink (case) of the TA2022. Even if
the internal VN10 regulator is not being used, VN10GND should still be connected to PGND.
TA2022 Amplifier Gain
The gain of the TA2022 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
A
VTA2022 = AVINPUTSTAG
E
* AV MODULATOR
R
F
R
FBC * (RFBA + RFBB )
VTA2022 ≈ −
+ 1
R
I
R
FBA * RFBB
For example, using a TA2022 with the following external components,
RI = 20kΩ
RF = 20kΩ
RFBA = 1kΩ
RFBB = 1.13kΩ
R
FBC = 9.09kΩ
20k Ω 9.09k Ω * (1.0k Ω + 1.13k Ω)
V
V
A
VTA2022 ≈ −
+ 1 = 18.13
20k Ω
1.0k Ω * 1.13k Ω
Input Stage Design
The TA2022 input stage is configured as an inverting amplifier, allowing the system designer flexibility
in setting the input stage gain and frequency response. Figure 1 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.
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TA2022 – KLI/1.2/07-04
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
