Using The TPA0103 EVM With the
3.3.2.3S3 Ð Input Select Jumper
To select the line inputs, set input select jumper S3 to OFF. To select the headphone inputs, set input select jumper S3 to ON.
The TPA0103 amplifier IC has two separate inputs for each of the left and right stereo channels. An internal multiplexor selects which input will be connected to the amplifier based on the state of the HP/LINE pin on the IC. However, the EVM HP/L* control input pin is not directly controlled by anything on the platform Ð the platform socket for that module pin is N/C. The amplifier IC HP/LINE control pin can be tied high manually via jumper S3 or connected to the amplifier IC Mode A control pin via jumper S5 so that it follows that control signal.
For manual control, jumper S3 connects the HP/L* module control input pin to VDD, so that when S3 is ON, the headphone inputs are selected. When S3 is OFF, a pulldown resistor on the module holds the IC shutdown control input pin low, selecting the line inputs.
3.3.2.4S5 Ð Autosense Jumper
To have the IC amplifier input select control input pin (HP/Line) follow the state of the Mode A IC output mode select pin, set autosense jumper S5 to ON. This automatically selects the headphone inputs when the Mode A control input goes high.
Note that when autosense jumper S5 is set to ON, amplifier IC control input pins HP/Line and Mode A are tied to VDD, and the Mode A control signal will have no effect if either jumper S3 or jumper S4 are set to ON.
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