Tri p ath Techn o l o g y, I n c. - T echn i cal I n fo rmation

8

TCA2002 – KLi/0.95/04.06

APPLICA T ION INFORMATION

T C A 2 0 02 B asic Op era t io n

The TCA2002 is a 5V CMOS stereo signal processor that amplifies the audio input signal and

converts the audio signal to a 1-bt complementary, Class-T

pattern is spread spectrum with a typical idle switching frequency of about 650kHz, externally

channels are not synchronized and the idle switching frequencies should differ by at least 40kHz to

avoid increasing the audio band noise floor. The idle frequency difference can be accomplished by

Complementary copies of the switching pattern are output through the Y1 and Y1B pins, and the Y2

and Y2B pins. These signals are used to drive the inputs of a MOSFET driver or integrated power

stage. Additionally, “break-before-make” or dead-time can be added between the Yx and YxB

transitions to minimize shoot-through currents in the output stage. This is adjusted by the BBM1 and

BBM0 pins.

The TCA2002 can be used over a wide range of supply voltages. The supply range is determined by

the values of the feedback resistors in conjunction with the over-voltage / under-voltage sense

resistors.

The TCA2002 has over-voltage and under-voltage detection as well as overcurrent detection. These

external inputs cause both channels of the amplifier to mute during the fault condition.

Class T A m p lifier A r ch itectu r e

Figure 1: Amplifier Architecture (One Channel)

A basic Class T Amplifier Architecture is shown in Figure 1. There are three main blocks in the signal

chain, though in some applications the FET Driver and MOSFETs may be integrated into a single

package.

The TCA2002 accepts an analog input signal. It processes this analog signal and converts it into a

complementary bitstream. This bitstream serves as the input to the FET Driver. The FET Driver

completes the appropriate level shifting and signal buffering to drive the gates of the Mosfet output

stage. Differential feedback is taken at the output and is used by the TCA2002 to ensure high signal

fidelity. The output filter recovers the amplified signal and connects to the loudspeaker.

Figure 1 is a very simplified architecture diagram. Please refer to the more detailed block diagrams

for the various amplifier configurations in the subsequent pages.

FET Driver

TCA2002

MOSFETS

OUTPUT

FILTER