Motorola 8900 - Blackberry Curve Cell Phone OEM Car Charger, Руководство разработчика

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Audio Interface
30 C24 Module Hardware Description December 15, 2008
Alert Loudspeaker Port
The alert loudspeaker is the default C24 power-up ringer. It is used for, but not limited to,
sounding the C24 alerts, melodies, and rings. It is located at pins 63 and 65 on the C24 interface
connector, named ALRT_N and ALRT_P respectively.
It is designed with an internal amplifier supplied directly from VCC, which supplies 0.5W to the
audio device. It may also be used as a single-ended output referenced to the C24 analog ground.
Figure 2-19 shows the alert loudspeaker circuit and Table 2-9 gives the loudspeaker
specifications.
Figure 2-19: Differential Loudspeaker Circuit
Important:
For safety regulations it is important to place series resistors on the alert output
lines, as illustrated in
Figure 2-19 . The resistors value should be R = 0
Ω
at the
design stage, but may be changed to a different value during audio safety testing, in
case that alert level limitation is required.
Figure 2-20: SIngle-ended Loudspeaker Circuit