Enfora GSM2218 - Manual (Page 20)

GSM2218PB001MAN - GSM/GPRS MT-GL User Manual Page 13
Copyright 2005, Enfora L.P
2.4 Audio In/Audio Out
The only way of connecting the microphone/speaker is via pins 3 - 6 of the 12-pin connector.
!
Please follow the specifications as listed in the table
below. Enfora is not liable for damage to the MT-GL
caused due to user error.
Ear – Speaker Output:
Parameter
Conditions MIN TYP MAX
UNIT
Maximum Input Range –
Mic(+) to Mic(-) Inputs 3 dBm0 (Max. digital
sample amplitude when PGA
gain set to 0 dB) 32.5
mVrms
Nominal Ref. Level –
Mic(+) to Mic(-) -10
dBm0
Differential Input
Resistance –
Mic(+) to Mic(-) 100
k
Ω
Microphone Pre-Amplifier
Gain 25.6
dB
Bias Voltage on Mic(+) 2.0 or 2.5 V 2.0 2.5
Vdc
Mic Bias Current Capability 0 0.5
mA
Handset Speaker Output
Parameter Conditions MIN TYP MAX UNIT
Maximum Swing –
Ear(+) to Ear(-) R
L
= 32
Ω & 5% distortion 1.2 1.5 V
pp
Maximum Capacitive Load –
Ear(+) to Ear(-) 100 pF
Amplifier Gain 1 dB
Amplifier State in Power Down High Z
Table 2 - Audio Settings