Tripath Technology, Inc. - Technical Information
A P P L I C A T I O N I N F O R M A T I O N
Basic Op e ratio n
The TP2050 is a MOSFET output stage that level-shifts the signal processor’s 5V switching patterns
to the power supply voltages and drives the power MOSFETs. The power MOSFETs are
complementary N-channel/P-channel devices configured in full-bridges and are used to supply power
to the output load. The outputs of the power MOSFETs must be low pass filtered to remove the high
frequency switching pattern. A residual voltage from the switching pattern will remain on the speaker
outputs when the recommended output LC filter is used, but this signal is outside of the audio band
and will not affect audio performance.
C i r cu i t B o ard L a yo u t
The TP2050 is a power (high current) power stage that operates at relatively high switching
frequencies. The output of the amplifier switches between VCC and GND at high speeds while
driving large currents. This high-frequency digital signal is passed through an LC low-pass filter to
recover the amplified audio signal. Since the amplifier must drive the inductive LC output filter and
speaker loads, the amplifier outputs can be pulled above the supply voltage and below ground by the
energy in the output inductance. To avoid subjecting the TP2050 to potentially damaging voltage
stress, it is critical to have a good printed circuit board layout. It is recommended that Tripath’s layout
and application circuit be used for all applications and only be deviated from after careful analysis of
the effects of any changes.
The following components are important to place near their associated TP2050 pins and are ranked
in order of layout importance, either for proper device operation or performance considerations.
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The capacitors CHBR provide high frequency bypassing of the amplifier power supplies and
will serve to reduce spikes across the supply rails. CHBR should be kept within 1/8” (3mm)
of the VCC pins. Please note that the four VCC pins must be decoupled separately. In
addition, the voltage rating for CHBR should be 50V as this capacitor is exposed to the full
supply range. Similarly, capacitors CS should be located as close as possible to their
respective pins on the TP2050.
In general, to enable placement as close to the TP2050, and minimize PCB parasitics, the capacitors
listed above should be surface mount types (with the exception of the bulk CHBR capacitor).
T P 2 0 5 0 O u t p u t C a p a b i l i t y
The TP2050 can drive two 8 Ohm loads with 40 Watts each at less than 0.05% THD+N. The
maximum sustained amplifier output power will be determined by a number of factors including the
TP2050 junction temperatures, the load impedance and the power supply voltage.
Tripath does not recommend driving loads below 6 Ohms single ended as the amplifier efficiency will
be reduced and the amplifier will reach it’s current limit at relatively low power output levels. With the
outputs connected in parallel, however, the TP2050 is capable of driving single channel loads down
to 4 Ohms with very high power capability.
Paralleled Outputs
For stereo mode operation, the TP2050 is a dual full bridge. For parallel mode operation, the TP2050
can be configured as a single full bridge with double current capability by connecting the CONFIG pin
to the VDD pin of the TP2050. Please refer to the Application/Test Diagram for parallel operation.
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TP2050– KL/1.0/07.05
TRIPATH [ TRIPATH TECHNOLOGY INC. ]
