TA2022 Ver la hoja de datos (PDF) - Tripath Technology Inc.

Número de pieza

componentes Descripción

Fabricante

TA2022

STEREO 90W (4Ω) CLASS-T™ DIGITAL AUDIO AMPLIFIER DRIVER USING DIGITAL POWER PROCESSING (DPP™) TECHNOLOGY

Tripath Technology Inc. 

Tripath Technology, Inc. - Technical Information

1/2 TA2022

V5

RFBA RFBA

Processing

&

Modulation

FBKOUT1

FBKGND1

RFBC

RFBC

RFBB RFBB

ROFB

10K

ROFA

50K

AGND

OUT1

OUT 1 GROUND

Figure 5: Manual Output Offset Trim Circuit

A DC servo can also be used to automatically null any offset voltage. The TA2022 evaluation board

incorporates a DC servo. Please refer to the TA2022 evaluation board document, EB-TA2022,

available on the Tripath website, at www.tripath.com.

Current Protection Design

Although the over-current (Ioc) trip point is internally fixed, there are external components that can

affect output current levels during a short circuit event. Referring to the Application/Test diagram

these include the output inductor (Lo), output diodes (Do) and supply bypassing (Cs).

The two output inductors, Lo, directly impact the peak output current levels reached during short

circuit events. For this reason they must be rated at least 10A regardless of the systems maximum

operating current, ensuring the inductor does not saturate which could lead to switching currents

passing unimpeded to the load. When this occurs, the Ioc may be forced to trip on average current

levels instead of peak current levels, directly impacting the current levels seen by the load and

potentially causing damage to the TA2022. Please refer to the Output Filter Design section for more

details on the inductor requirements and figure 6 for comparison of load currents with an unsaturated

and saturated inductor.

The four output diodes, Do, minimize overshoots and undershoots with respect to the supply rails

VPP and VNN. In order for these diodes to work properly they must have a low Forward Voltage

rating at 10A. We recommend a Fast Recovery diode or Ultra-Fast PN Rectifier diode with a Vf rating

of 1V at 10A, or better. Also, These should be placed close to their respective output pins to

maximum effectiveness.

The two bulk supply voltage capacitors, Cs, will absorb the current generated when the diodes (Do)

conduct. We recommend that a high frequency capacitor designed for low impedance and high ripple

currents be used. Tripath recommends an impedance of .1Ω or better at 100kHz and a ripple current

rating of 1Arms at 100kHz. For maximum effectiveness, Tripath recommends that these capacitors be

placed close to their respective supply pins.

20

TA2022 – KLI/1.2/07-04

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