TECHNICAL INFORMATION
R
VNN1
R
VNN2
R
VPP1
R
VPP2
R
S
R
OCR
C
OCR
C
HBR
R
G
C
Z
R
Z
L
O
ground as shown in the Application/Test Circuit.
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.
Secondary overvoltage and undervoltage sense resistor for the negative supply
(VNN). This resistor accounts for the internal V
NNSENSE
bias of 1.25V. Nominal
resistor value should be three times that of R
VNN1
. 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 V
PPSENSE
bias of 2.5V. Nominal
resistor value should be equal to that of R
VPP1
. 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.
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 R
S
to obtain a specific current limit trip point.
Over-current “trim” resistor, which, in conjunction with R
S
, 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 R
OCR
.
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 TA3020. A
typical value for this component is 220pF. In addition, this component should be
located near pin 31 or pin 33 as possible.
Supply decoupling for the high current Half-bridge supply pins. These components
must be located as close to the device as possible to minimize supply overshoot and
maximize device 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.
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.
Zobel capacitor, which in conjunction with R
Z
, 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 C
Z
, terminates the output filter at high
frequencies. The combination of R
Z
and C
Z
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 R
Z
may need to be adjusted. The typical
power rating is 2 watts.
Output inductor, which in conjunction with C
O
, demodulates (filters) the switching
waveform into an audio signal. Forms a second order filter with a cutoff frequency
TA3020, Rev 2.1, 01.01
9
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
