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written agreement.
WM_PRJ_Q2686_PTS_001-010
June 30, 2009
Q2686 Wireless CPU
®
Electrical Characteristics of MIC1
Parameters
Min Typ Max
Unit
DC Characteristics
N/A
V
AC Characteristics
200 Hz<F<4 kHz
Z1
70
120 160
k
Ω
AT+VGT*=3500
(4)
13.8 18.6*** mVrms
AT+VGT*=2000
(4)
77.5 104*** mVrms
Working voltage
( MIC1P-MIC1N)
AT+VGT*=700
(4)
346 465*** mVrms
Positive
+7.35
V
Maximum rating
voltage
(MIC1P or MIC1N)
Negative
-
0.9
•
*The input voltage depends of the input micro gain set by AT command. Please refer to the
document :AT command User Guide [7]
•
**Because MIC2P is internally biased, it is necessary to use a coupling capacitor to
connect an audio signal provided by an active generator. Only a passive microphone can
be directly connected to the MIC2P and MIC2N inputs.
•
*** This value is obtained with digital gain = 0 and for frequency
=
1kHz :
•
(4)
This value is given in dB, but it’s possible to toggle to index value. Please refer to the
document :AT command User Guide [7]
WARNING:
The voltage input value for MIC1 can’t exceed the maximum working voltage,
otherwise clipping will appear.
3.11.1.2
MIC2 Microphone Inputs
By default, the MIC2 inputs are differential ones, but it can be configured in
single ended. They already include the convenient biasing for an electret
microphone. The electret microphone can be directly connected on those
inputs, thus allowing easy connection to a handset.
AC coupling is already embedded in the Wireless CPU
®
.
Equivalent circuits of MIC2
DC equivalent circuit
AC equivalent circuit
MIC2P
MIC2N
Z2
Z2 GND
MIC2+
MIC2P
MIC2N
R
R
GND