Example-Mic Differential Connection With Lc Filter (Tbd) - Sierra Wireless AirPrime SL808 Series Product Technical Specification & Customer Design Manuallines

Product Technical Specification & Customer Design Guidelines
Table 4-22: Microphone interface parameters
Parameter / Description
Input DC common mode
voltage
Z Input impedance between
In1
MIC1_P and MIC1_N
THD Total harmonic distortion
V
+Noise (voice)
a. Preliminary values
MIC
54 Proprietary and Confidential - Specifications subject to change
Test
Fully differential, A/D path
All inputs:
•
•
•
•
Caution: The voltage input value for MIC cannot exceed the maximum working voltage;
otherwise, clipping will appear.
MIC differential connection example
L1
C1
L2
Figure 4-4: Example—MIC differential connection with LC filter (TBD)
LC filter (L1, L2, C2, C3, C4) considerations:
• Filter is not mandatory. Audio quality may be good enough without it,
depending on the design.
• Filter may be used to reduce TDMA noise (from EMI perturbation).
AV = 2.5 V
DD
13-bit mode
analog input at 229 mV
pp
498 Hz sine wave
1.2V typ
C2
S3
MIC1_P
C3
MIC1_N
S4
C4
a a a
Min Typ Max
1.13 1.25 1.38
16 20 24
3.5
AirPrime SL module
1350 Ohm typ
Audio
ADC
100nF
100nF
1350 Ohm typ
Units
V

k
%
2400058