C24 Hardware Interface Manual
Version 0.3
2.8.3 Speaker Port
The analog speaker port is the module’s power-up default active output for voice calls and DTMF tones. It
is located at pins 67 and 69 on the interface connector, named SPKR_N and SPKR_P respectively.
It is designed as a differential output with 32Ω impedance, but may also be used as a single-ended output
referenced to the module’s analog ground.
The speaker output is used for both the handset and the headset audio paths.
TABLE 10 – Speaker Port Specifications
Parameter Conditions Min
Typ Max Units
Output
No load 2 V
PP
Voltage
Gain
Programmable in 3 dB steps
Handset mode
Headset mode
(See table 17)
-35.8 -14.8
dB
-28.8
-7.8
AC Output
32 Ω
Impedance
DC voltage 1 V
THD 32Ω load 0.15 %
Isolation Speech, f > 4 KHz 60 dB
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