Tripath Technology, Inc. - Technical Information
External Components Description (Refer to the Application/Test Circuit)
Components Description
RI
RF
CI
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.
AC input coupling capacitor which, in conjunction with RI, forms a highpass 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 TK2350 gain in conjunction with RI,
RF, RFBA, and RFBC. Please see the Modulator Feedback Design paragraphs in the
Application Information Section.
RFBC
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 TK2350 gain in conjunction with RI, RF,
RFBA,, and RFBB. It should be noted that the resistor from OUT1(OUT2) to
2
FBKOUT1(FBKOUT2) must have a power rating of greater than
.
P
= VPP (2RFBC)
DISS
Please see the Modulator Feedback Design paragraphs in the Application
Information Section.
CFB
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.
ROFA
ROFB
Potentiometer used to manually trim the DC offset on the output of the TK2350.
Resistor that limits the manual DC offset trim range and allows for more precise
adjustment.
RREF
CA
Bias resistor. Locate close to pin 15 of the TC2001 and ground at pin 20 of the
TC2001.
BIASCAP decoupling capacitor. Should be located close to pin 1 of the TC2001 and
grounded at pin 20 of the TC2001.
DB
Bootstrap diode. This diode charges up the bootstrap capacitors when the output is
low (at VNN) to drive the high side gate circuitry. A fast or ultra fast recovery diode
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 150V (or
greater) diode should be used.
CB
High frequency bootstrap capacitor, which filters the high side gate drive supply.
This capacitor must be located as close to VBOOT1 (pin 57 of the TP2350B) or
VBOOT2 (pin 27 of the TP2350B) for reliable operation. The “negative” side of CB
should be connected directly to the HO1COM (pin 47 of the TP2350B) or HO2COM
(pin 37 of the TP2350B). 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.
CBAUX
RB
Bootstrap resistor that limits CBAUX charging current during TK2350 power up
(bootstrap supply charging).
CS
Supply decoupling for the power supply pins. For optimum performance, these
components should be located close to the TC2001 and TP2350B and returned to
their respective ground as shown in the Application/Test Circuit.
RVNN1
Main overvoltage and undervoltage sense resistor for the negative supply (VNN).
Please refer to the Electrical Characteristics Section for the trip points as well as the
hysteresis band. Also, please refer to the Over / Under-voltage Protection section in
the Application Information for a detailed discussion of the internal circuit operation
and external component selection.
11 of 11
TK2350, Rev 1.5/09.03
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
