July 16, 2004 6881094C28-D
3-6 Basic Theory of Operation: VOCON Board
The digital support IC also monitors the position of the on/off switch and controls the shutdown of the
regulators on the audio and power supply IC. Finally, the digital support IC interfaces to the radio’s
universal (accessory) connector. This IC is programmed by the dual-core processor.
The audio and power supply IC has many functions. It supplies most of the voltages used on the
VOCON board, while external linear regulators supply 5 Vdc and 1.55 Vdc. It also has microphone
audio amplifiers, switching between internal and accessory microphones, and the audio CODEC.
The audio CODEC performs analog-to-digital and digital-to-analog conversions on audio signals.
The audio and power supply IC also has an analog/digital converter (ADC), which is used to monitor
volume setting and battery voltage. This IC is programmed by the dual-core processor.
The audio power amplifier (PA) drives the speakers with the received audio from the analog output of
the CODEC from the audio and power supply IC. The audio PA is sourced from the battery and
programmed by the dual-core processor.
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