Sierra Wireless AirPrime SL808 Series, Product Technical Specification & Customer Design Manuallines, Page: 52 / 122

Product Technical Specification & Customer Design Guidelines
52 Proprietary and Confidential - Specifications subject to change 2400058
4.10 Analog audio interface
The AirPrime SL808X Embedded Module analog audio interface supports one
microphone input and one speaker output.
Table 4-15 describes the purpose and features of this interface.
4.10.1 Pin descriptions
Table 4-20 describes the analog audio interface pins.
4.10.2 Microphone features
The microphone can be connected in either differential or single-ended mode:
• Differential mode—Default method (recommended). Rejects common mode
noise and TDMA noise.
• Single-ended mode—Requires good ground plane, filtering and shielding to
avoid audio path disturbances. Note that the audio input signal is decreased
by 6 dB compared to differential mode.
Table 4-19: Audio interface features
Feature Details
Implementation
•
Supports analog audio processing
•
Does not provide on-board filtering (except for
0.1
µ Fblocking capacitors on microphone lines)
•
Host must provide bias and signal filters
•
Host should terminate unused audio lines with pull-down
resistors
•
ESD protection may be required on audio interface lines
Features
•
Echo cancellation and noise reduction
•
TTY/TDD compatibility through the microphone/speaker
connections (Note: TTY/TDD is not supported by the PCM
interface.)
Table 4-20: Analog audio interface connections
Pin Name I/O type Description Type Notes
53 MIC1_P Line Audio input A Differential audio input, line level. In series
with 0.1µF DC blocking capacitor.
54 MIC1_N Line Audio input A Differential audio input, line level. In series
with 0.1µF DC blocking capacitor.
56 SPK_N Main speaker A Differential audio output, line level
57 SPK_P Main speaker A Differential audio output, line level