Headset Detection; Speaker Port Specifications - Motorola 8900 - Blackberry Curve Cell Phone OEM Car Charger Developer's Manual

Important:

Headset Detection

The C24 operates by default in the basic audio mode with the handset audio path, for DTMF
tones and speech, and the alert loudspeaker port, for rings and alert tones.
The headset path is an alternate audio path in basic mode. It is designed for, but not limited to, a
personal hands-free audio device, a headset, using the headset microphone input port and the
speaker output port.
The HDST_INT_N signal is used to switch between handset and headset audio paths in basic
audio mode. This signal is set high by default at power up. Asserting the HDST_INT_N signal
low enables the headset audio path and disables the handset and alert paths. Setting this signal
high will disable the headset path and enable the handset and alert audio paths.
The C24 supports dynamic switching between the handset and headset audio paths, during
operation and call handling.
Important:
December 15, 2008
When implementing a single ended speaker design, it is required to place a series
capacitor and resistor on the speaker output line, as illustrated in
The capacitor should be of low tolerance with values of C = 10-22 uF.
The resistor value depends on the speaker application:
- For a handset device, the resistor value should be R = 0
may be changed to a different value during audio safety testing, in case speaker
level limitation is required.
- For a headset device, safety regulations require the resistors value to be R > 2R
where R is the speaker impedance (e.g. 32
L
For example, when using a 32
Table 2-8: Speaker Port Specifications
Parameter Conditions
Output No load
Voltage
Gain Programmable by
AT Command
AC Output
Impedance
DC Voltage
THD 32 Ω load 200 Hz
- 20 kHz
The HDST_INT_N signal does not operate in advanced audio mode. This signal's
functionality is overridden by the AT+MAPATH command settings.
C24 Module Hardware Description
Chapter 2: Hardware Interface Description
).
Ω
speaker the series resistance would be R > 64
Ω
Min Typ Max
2.1
-3 17
32
1
0.1
Figure 2-18.
at the design stage, but
Ω
,
Ω
L
.
Ω
Unit
V
pp
dB
Ω
V
%
29