Tripath Technology, Inc. - Technical Information
RVNN2
RVPP1
RVPP2
Secondary overvoltage and undervoltage sense resistor for the negative supply
(VNN). This resistor accounts for the internal VNNSENSE bias of 1.25V. Nominal
resistor value should be three times that of RVNN1. 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.
Main overvoltage and undervoltage sense resistor for the positive supply (VPP).
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.
Secondary overvoltage and undervoltage sense resistor for the positive supply
(VPP). This resistor accounts for the internal VPPSENSE bias of 2.5V. Nominal
resistor value should be equal to that of RVPP1. 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.
RS
Over-current sense resistor. Please refer to the section, Setting the Over-current
Threshold, in the Application Information for a discussion of how to choose the value
of RS to obtain a specific current limit trip point.
ROCR
Over-current “trim” resistor, which, in conjunction with RS, sets the current trip point.
Please refer to the section, Setting the Over-current Threshold, in the Application
Information for a discussion of how to calculate the value of ROCR
.
COCR
Over-current filter capacitor, which filters the overcurrent signal at the OCR pins to
account for the half-wave rectified current sense circuit internal to the TC2001. A
typical value for this component is 220pF. In addition, this component should be
located near pin 14 or pin 16 of the TC2001 as possible.
CHBR
Supply decoupling for the high current Half-bridge supply pins. These components
must be located as close to the output MOSFETs as possible to minimize output
ringing which causes power supply overshoot. By reducing overshoot, these
capacitors maximize both the TP2350B and output MOSFET reliability. These
capacitors should have good high frequency performance including low ESR and
low ESL. In addition, the capacitor rating must be twice the maximum VPP voltage.
Panasonic EB capacitors are ideal for the bulk storage (nominally 33uF) due to their
high ripple current and high frequency design.
RG
DG
Gate resistor, which is used to control the MOSFET rise/ fall times. This resistor
serves to dampen the parasitics at the MOSFET gates, which, in turn, minimizes
ringing and output overshoots. The typical power rating is 1 watt.
Gate diode, placed in parallel to the gate resistor. This diode will help discharge the
parasitic capacitance at the MOSFET gates, thus decreasing the MOSFET fall time.
This helps reduce shoot through current between the top side and bottom side
output MOSFETs.
CZ
RZ
Zobel capacitor, which in conjunction with RZ, terminates the output filter at high
frequencies. Use a high quality film capacitor capable of sustaining the ripple current
caused by the switching outputs.
Zobel resistor, which in conjunction with CZ, terminates the output filter at high
frequencies. The combination of RZ and CZ minimizes peaking of the output filter
under both no load conditions or with real world loads, including loudspeakers which
usually exhibit a rising impedance with increasing frequency. Depending on the
program material, the power rating of RZ may need to be adjusted. The typical
power rating is 2 watts.
LO
Output inductor, which in conjunction with CO, demodulates (filters) the switching
waveform into an audio signal. Forms a second order filter with a cutoff frequency
of
and a quality factor of
.
LO CO
fC = 1 (2π LO C O
)
Q = RL CO
CO
Output capacitor, which, in conjunction with LO, demodulates (filters) the switching
waveform into an audio signal. Forms a second order low-pass filter with a cutoff
frequency of
and a quality factor of
)
. Use
LO CO
fC = 1 (2π LO C O
Q = RL CO
a high quality film capacitor capable of sustaining the ripple current caused by the
switching outputs.
DD
Drain diode. This diode must be connected from the drain of the high side output
12 of 12
TK2350, Rev 1.5/09.03
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
