TCA2002 Datasheet, PDF (8/18 Pages) Tripath Technology Inc. – STEREO CLASS-T™ AUDIO CONTROLLER USING DIGITAL POWER PROCESSING (DPP™) TECHNOLOGY

Tripath Technology, Inc. - Technical Information
APPLICATION INFORMATION
TCA2002 Basic Operation
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^TM, switching pattern. This switching
pattern is spread spectrum with a typical idle switching frequency of about 650kHz, externally
adjustable by the output stage propagation delay and C_FB. The switching patterns for the two
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
offsetting the value of C_FB for each channel.
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 Amplifier Architecture
TCA2002
FET Driver
MOSFETS
OUTPUT
FILTER
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.
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TCA2002 – KLi/0.95/04.06