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Using The TPA122 MSOP EVM With the Plug-N-Play Evaluation Platform
3-10
Details
3.3.5 Inputs and Outputs
The TI Plug-N-Play Audio Amplifier Evaluation Platform is equipped with
several standard conectors for audio inputs and outputs.
3.3.5.1 Inputs
In most cases, audio signals enter the platform through either a pair of RCA
phono jacks (J3 and J5) or a miniature (1/8″) stereo phone jack (J4). Certain
signal conditioning and amplifier EVMs, however, may have additional signal
input connectors mounted on the module circuit board.
The platform audio signal input jacks (J3, J4, and J5) are of the closed-circuit
type, grounding the signal input lines when no plugs are inserted.
3.3.5.2 Outputs
Output signals from the headphone amplifier (U5) leave the platform through
a miniature (1/8″) stereo headphone jack (J10). Amplified audio output signals
from the power amplifiers (U2 – U4) leave the platform through left and right
RCA phono jacks (J7 and J9), left and right pairs of compression connectors
for stripped speaker wires (J8), and optionally, through the headphone jack.
The audio output lines from the power amplifiers are separate all the way to
the edge of the platform (output jacks J7, J8, and J9) — the OUT– lines from
the power amplifier sockets are not tied to each other or to platform ground.
This allows the power amplifier EVMs to operate in the highly-efficient
bridge-tied load configuration.
The headphone jack (J10) is capacitively coupled to source select switch S3,
which connects J10 to the output lines of either the headphone amplifier
socket or the power amplifier sockets (Figure 3–5). When the TPA122 MSOP
EVM output signal is routed to J10 by S3, signals output via J10 are returned
to platform ground when a plug is inserted (Figure 3–7).
Figure 3–7. Typical Headphone Plug
Left Right GND