Figure 3-29. Rx Audio Path Block Diagram - Motorola APX 3000 Detailed Service Manual

Theory of Operation
: Controller
3.2.5.2 RX Audio path
The RX audio path supports one external speaker.
OMAP DSP
SSI
MCBSP1
ARM SPI
DSP
I2C
SPI
SSI I2C SPI
For the external speaker path, the digital audio data is sent from the OMAP1710's McBSP1 port to
the TI AIC33 CODEC for digital to analog conversion and volume control. The external speaker path
uses the MAKO IC's class-AB audio power amplifier to drive 16 Ohm to 28 Ohm external speakers.
The input to MAKO IC's audio power amplifier is fully differential and comes from the TI CODEC's
RIGHT_LOP and RIGHT_LOM. The output of the MAKO IC's audio amplifier is also fully differential
and available on pins EXT_SPKR_P and EXT_SPKR_M.
MAKO
SSI
SPI
Low - Pass Filter
20kHz Corner
TI CODEC
RIGHT LINE
OUT
LEFT LINE
OUT

Figure 3-29. RX Audio Path Block Diagram

AB AMP
Switch
AB AMP
3-37
External/
Accessory Speaker
~ 16-20 Ohms