TA3020 Ver la hoja de datos (PDF) - Unspecified
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TA3020 Datasheet PDF : 27 Pages
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Tripath Technology, Inc. - Technical Information
- To minimize the possibility of any noise pickup, the trace lengths of INV1 and INV2 should be kept as
short as possible. This is most easily accomplished by locating the input resistors, RI and the input
stage feedback resistors, RF as close to the TA3020 as possible. In addition, the offset trim resistor,
ROFB, which connects to either INV1,or INV2, should be located close to the TA3020 input section.
TA3020 Grounding
Proper grounding techniques are required to maximize TA3020 functionality and performance. Parametric
parameters such as THD+N, Noise Floor and Crosstalk can be adversely affected if proper grounding
techniques are not implemented on the PCB layout. The following discussion highlights some
recommendations about grounding both with respect to the TA3020 as well as general “audio system” design
rules.
The TA3020 is divided into two sections: the input section, which spans pin 12 through pin 37, and the output
(high voltage) section, which spans pin 1 through pin 10 and pin 39 through pin 48. On the TA3020 evaluation
board, the ground is also divided into distinct sections, one for the input and one for the output. To minimize
ground loops and keep the audio noise floor as low as possible, the input and output ground must be only
connected at a single point. Depending on the system design, the single point connection may be in the form
of a ferrite bead or a PCB trace.
The analog grounds, pin 28 and pin 34 must be connected locally at the TA3020 for proper device functionality.
The ground for the V5 power supply should connect directly to pin 28. Additionally, any external input circuitry
such as preamps, or active filters, should be referenced to pin 28.
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 TA3020.
The TA3020 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.
TA3020 Amplifier Gain
The gain of the TA3020 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 * A VTA3020
VINPUTSTAG E
V MODULATOR
A VTA3020 ≈ − R F R FBC * (R FBA + R FBB ) + 1
RI
R FBA * R FBB
For example, using a TA3020 with the following external components,
RI = 20kΩ
RF = 20kΩ
RFBA = 1kΩ
RFBB = 1.13kΩ
RFBC = 9.09kΩ
AVTA3020 ≈ − 20k Ω 13.3k Ω * (1.0k Ω + 1.07k Ω ) + 1 = - 10.71 V
49.9k Ω
1.0k Ω * 1.07k Ω
V
16
TA3020 – KL Rev. 3.0/09.03
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