Tri p ath Techn o l o g y, I n c. - T echn i cal I n fo rmation

10

TP2050– KL/1.0/07.05

APPLICA T ION INFORMATION

Basic Op e r atio 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.

Circ uit Boa r d Lay out

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.

-

of the VCC pins. Please note that the four VCC pins must be decoupled separately. In

respective pins on the TP2050.

In general, to enable placement as close to the TP2050, and minimize PCB parasitics, the capacitors

TP2050 Output Capability

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 Outp uts

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.