Tripath Technology, Inc. – Technical Information
External Components Description
(Refer to the Connection Diagram)
Components
C
S
C
BR
Description
Supply decoupling for the power supply pins. For optimum performance, these
components should be located close to the TPS4100A and returned to their
respective “ground” as shown in the Application/Test Circuit.
Supply decoupling for the high current full-bridge supply pins. These components
must be located as close to the power supply pins as possible to minimize output
ringing which causes power supply overshoot. By reducing overshoot, these
capacitors maximize the TPS4100A reliability. These capacitors should have good
high frequency performance including low ESR and low ESL.
Supply decoupling for the charge pump (high side gate drive supply) circuitry.
These components must be located as close to the TPS4100A as possible.
Output diode, which is used to minimize output overshoots/undershoots on the
output nodes These devices clamp the output to the low impedance node formed
by the close connection of C
BR
. Note the connection shown in the Application/Test
Circuit. The “high side” diode protects the bottom side device from excessive
BVDSS due to overshoots on the output node. The “bottom side” diode protects the
top side device from excessive BV
DSS
due to undershoots on the output node. This
device must be an ultra fast rectifier capable of sustaining the entire supply range
and high peak currents.
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. If the system
requires full power operation at 20kHz then the power rating for R
Z
will likely need to
be increased.
Output inductor, which in conjunction with C
O
and C
DO
, demodulates (filters) the
switching waveform into an audio signal. Forms a second order filter with a cutoff
frequency of
f
C
=
1 ( 2
π
L
O
C
TOT
)
and a quality factor of
C
CP
D
O
C
Z
R
Z
L
O
Q
=
R
L
C
TOT
C
O
R
FAULT
D
CP
2 L
O
C
TOT
where C
TOT
= C
O
.
Output capacitor, which, in conjunction with L
O
, demodulates (filters) the switching
waveform into an audio signal. Use a high quality film capacitor capable of
sustaining the ripple current caused by the switching outputs.
Pull-up resistor for the open drain FAULT pin output. Recommended resistor value
is 51kΩ.
Charge pump diodes. Used to generate floating supply for driving high side
circuitry. Small signal diodes such as 1N4148 are recommended for these
components.
7
TPS4100A – KL/Rev. 1.1/11.05
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
