Tripath Technology, Inc. - Technical Information
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)
Components
Description
RI
Inverting input resistance to provide AC gain in conjunction with RF. This input is biased
at the BIASCAP voltage (approximately 2.5VDC).
Feedback resistor to set AC gain in conjunction with RI. Please refer to the Amplifier
Gain paragraph, in the Application Information section.
RF
CI
AC input coupling capacitor which, in conjunction with RI, forms a high pass filter at
.
fC = 1 (2πRICI)
RFBA
RFBB
Feedback divider resistor connected to V5. This resistor is normally set at 1kΩ.
Feedback divider resistor connected to AGND. This value of this resistor depends on
the supply voltage setting and helps set the TA2022 gain in conjunction with RI, RF, RFBA,
and RFBC. Please see the Modulator Feedback Design paragraphs in the Application
Information Section.
Feedback resistor connected from either the OUT1(OUT2) to FBKOUT1(FBKOUT2) or
speaker ground to FBKGND1(FBKGND2). The value of this resistor depends on the
supply voltage setting and helps set the TA2022 gain in conjunction with RI, RF, RFBA,, and
RFBC
RFBB. It should be noted that the resistor from OUT1(OUT2) to FBKOUT1(FBKOUT2)
2
must have a power rating of greater than
. Please see the Modulator
P
= VPP (2RFBC)
DISS
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 CFB 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 output of the TA2022.
Resistor that limits the manual DC offset trim range and allows for more precise
adjustment.
CFB
ROFA
ROFB
RREF
CA
DB
Bias resistor. Locate close to pin 17 and ground at pin 20.
BIASCAP decoupling capacitor. Should be located close to pin 27 and grounded at pin 20.
Bootstrap diode. This diode charges up the bootstrap capacitors when the output is low
(at VNN) to drive the high side gate circuitry. Schottky or fast recovery diode rated at
least 200mA, 90V, 50nS is recommended for the bootstrap circuitry. In addition, the
bootstrap diode must be able to sustain the entire VPP-VNN voltage. Thus, for most
applications, a 90V (or greater) diode should be used.
High frequency bootstrap capacitor, which filters the high side gate drive supply. This
capacitor must be located as close to pin 13 (VBOOT1) or pin1n (VBOOT2) for reliable
operation. The other side of CB should be connected directly to the OUT1 (pin 10) or
OUT2 (pin 7). Please refer to the Application / Test Circuit.
Bulk bootstrap capacitor that supplements CB during “clipping” events, which result in a
reduction in the average switching frequency.
Bootstrap resistor that limits CBAUX charging current during TA2022 power up (bootstrap
supply charging).
CB
CBAUX
RB
CSW
VN10 generator filter capacitors. The high frequency capacitor (0.1uF) must be located
close to pin 2 (VN10) to maximize device performance. The value of the bulk capacitor
should be sized appropriately such that the VN10 voltage does not overshoot with
respect to VNN during TA2022 turn on. Tripath recommends using a value of 100 F for
the bulk capacitor.
LSW
8
VN10 generator filter inductor. This inductor sized appropriately so that LSW does not
TA2022 – KLI/1.2/07-04
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
