Specifications

Rev 1 Dec.10 Proprietary and Confidential - Specifications subject to change 53
The gain of both MIC inputs are internally adjusted and can be tuned using AT
commands. For more information on AT commands, refer to [3] AirPrime MC8xxx
Embedded Modules Extended AT Command Reference.
4.10.2.1 MIC microphone input
The microphone input has the following features:
• Default mode—Differential. Can also be configured in single-ended mode.
• Includes biasing for electret microphone, which can be directly connected to
the input.
• AirPrime SL808X Embedded Module has embedded AC coupling.
• For electrical characteristics, see Table 4- 2 1.
Figure 4-3: MIC equivalent circuits
R
R
MIC1_P
MIC1_N
MIC+
GND
Z2
MIC1_P
MIC1_N
GND
Z2
DC equivalent circuit AC equivalent circuit
Table 4-21: MIC input electrical characteristics
Parameter Minimum Typical Maximum Unit
Parameters MIC1_P 2 2.1 2.2 V
Internal biasing Output current 0.5 1.5 mA
DC characteristics R2 1650 1900 2150

AC characteristics
200 Hz<F<4 kHz
Z2 MIC1_P (MIC1_N = Open) 1.1 1.3 1.6 k
Z2 MIC1_N (MIC1_P = Open)
Z2 MIC1_P (MIC1_N=GND) 0.9 1.1 1.4
Z2 MIC1_N (MIC1_P=GND)
Impedance between MIC1_P
and MIC1_N
1.3 1.6 2
Working voltage
(MIC1_P-MIC1_N)
AT+VGT
a
=3500
b
13.8 18.6
c
mVrms
AT+VGT
a
=2000
b
77.5 104
c
AT+VGT
a
=700
b
346 466
c
Maximum rating
voltage (MIC1_P
or MIC1_N)
Positive +7.35
d
V
Negative -0.9
a. Input voltage depends on the input micro gain set by AT command. Refer to [3] AirPrime MC8xxx Embedded Modules
Extended AT Command Reference
b. Value in dB. To toggle it to index value, refer to [3] AirPrime MC8xxx Embedded Modules Extended AT Command Refer-
ence.
c. Value is obtained with digital gain=0, for frequency=1 kHz.
d. Because MIC1_P is internally biased, a coupling capacitor must be used to connect an audio signal provided by an
active generator. Only a passive microphone can be directly connected to the MIC1_P and MIC1_N inputs.