Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on
E X T E R N A L C O M P O N E N T S D E S C R I P T I O N
(Refer to the Application/Test Circuit)
Component
RI
RF
CI
Description
Inverting input resistance to provide AC gain in conjunction with R
F
. This input is
biased at the BIASCAP voltage (approximately 2.5VDC).
Feedback resistor to set AC gain in conjunction with R
I
. Please refer to the
Amplifier Gain paragraph, in the Application Information section.
AC input coupling capacitor, which, in conjunction with R
I
, forms a high pass filter
at
f
C
=
1 (2
π
R
I
C
I
)
.
Feedback divider resistor connected to AGND. The value of this resistor depends
on the supply voltage setting and helps set gain in conjunction with R
I,
R
F,
R
FBB,
and R
FBC
. Please see the Modulator Feedback Design paragraphs in the
Application Information Section.
Feedback resistor connected from either the OUT1A/OUT2A to FDBKP1/FDBKP2
or OUT1B/OUT2B to FDBKN1/FDBKN2. The value of this resistor depends on
the supply voltage setting and helps set gain in conjunction with R
I,
R
F,
R
FBB,
and
R
FBC
. It should be noted that the resistor from OUT1/OUT2 to
FBKOUT1/FBKOUT2 must have a power rating of greater than
P
DISS
=
VPP
2
(2R
FBC
)
. Please see the Modulator Feedback Design paragraphs in
the Application Information Section.
Feedback delay capacitor that both lowers the idle switching frequency and filters
very high frequency noise from the feedback signal, which improves amplifier
performance. The value of C
FB
should be offset between channel 1 and channel 2
so that the idle switching difference is greater than 40kHz. Please refer to the
Application / Test Circuit.
Potentiometer used to manually trim the DC offset on the speaker output.
Resistor that limits the manual DC offset trim range and allows for more precise
adjustment.
Bias resistor. Locate close to pin 15 and ground at pin 20.
Supply decoupling for the power supply pins. For optimum performance, these
components should be located close to the TC2000 and returned to their
respective ground as shown in the Application/Test Circuit.
Resistor used to terminate the VNNSENSE pin to AGND.
Resistor used to terminate the VPPSENSE pin to 5V.
RFBB
RFBC
CFB
ROFB
ROFA
RREF
CS
RVNNSENSE
RVPPSENSE
APPLICATION INFORMATION
TK2050 Basic Amplifier Operation
The TC2000 is a 5V CMOS signal processor that amplifies the audio input signal and converts the
audio signal to a switching pattern. This switching pattern is spread spectrum with a typical idle
switching frequency of about 650kHz externally set by the CFB. 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 CFB for each channel. Typical values of CFB with the TP2050 are 470pF for
channel 1 and 390pF for channel 2.
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. In the generation of
the patterns for the MOSFET driver the TC2000 inserts a “break-before-make” dead time between the
5
TC2000 – KLI/1.1/12-03
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
