RB-TA3020-2 Ver la hoja de datos (PDF) - Tripath Technology Inc.

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RB-TA3020-2

CLASS-T DIGITAL AUDIO AMPLIFIER REFERENCE BOARD USING DIGITALPOWER PROCESSING (DPP™) TECHNOLOGY

Tripath Technology Inc. 

Tripath Technology, Inc. - Technical Information

28V (-1 VERSION)

45V (-2 VERSION)

28V (-1 VERSION)

45V (-2 VERSION)

10V

HEATSINK

M100

M101

M201

VPP

PGND

VNN

VN10

M200

-+

OUT1

GND1

Ch1

Offset

AGND

IN1

AGND

V5

TA3020

HMUTE LED

GND2

OUT2

AGND

IN2

Ch2

Offset

BBM1

BBM0

MUTE

AUDIO

SOURCE

Figure 9

Circuit Board Layout

The TA3020 is a power (high current) amplifier that operates at relatively high switching frequencies.

The output of the amplifier switches between VPP and VNN at high speeds while driving large

currents. This high-frequency digital signal is passed through an LC low-pass filter to recover the

amplified audio signal. Since the amplifier must drive the inductive LC output filter and speaker loads,

the amplifier outputs can be pulled above the supply voltage and below ground by the energy in the

output inductance. To avoid subjecting the TA3020 to potentially damaging voltage stress, it is critical

to have a good printed circuit board layout. It is recommended that Tripath’s layout and application

circuit be used for all applications and only be deviated from after careful analysis of the effects of any

changes. Please refer to the TA3020 evaluation board document, EB-TA3020, available on the

Tripath website, at www.tripath.com.

The following components are important to place near either their associated TA3020 or output

MOSFET pins. The recommendations are ranked in order of layout importance, either for proper

device operation or performance considerations. The component designators, referred to, are for

channel 1 of the RB-TA3020.

- The capacitors, CHBR (C105/C113), provide high frequency bypassing of the amplifier power

supplies and will serve to reduce spikes across the supply rails. Please note that both

mosfet half-bridges must be decoupled separately. In addition, the voltage rating for CHBR

should be at least 150V as this capacitor is exposed to the full supply range, VPP-VNN.

- DO (D106/D107) are also critical to the reduction of ringing on the outputs of the FETs.

They shunt the inductive energy if the output exceeds VPP or goes below VNN. The

proper connection of these diodes are “drain to drain” and “source to source” as shown in

the schematic diagrams. These diodes have a 200V rating.

- CFB (C107) removes very high frequency components from the amplifier feedback signals

and lowers the output switching frequency by delaying the feedback signals. In addition,

the value of CFB is different for channel 1 and channel 2 to keep the average switching

frequency difference greater than 40kHz. This minimizes in-band audio noise. Locate

these capacitors as close to their respective TA3020 pin as possible.

10

RB-TA3020, Rev. 3.0/03.02

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