Using The TPA122 MSOP EVM With the
3.3.5Inputs and Outputs
The TI
3.3.5.1Inputs
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
3.3.5.2Outputs
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) Ð 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
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
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