User's Manual
Table Of Contents
Audio Interface
Rev 1.12.4 Oct.09 Proprietary and Confidential 31
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.
Audio signal interface
Thedifferentialmicrophoneinputofferssuperiornoise
rejectionperformancetothesingle‐endedapproach.The
terminationofthedifferentialpairrejectscommonsignals
(suchasnoise).Thepairshouldberoutedtogetherforoptimal
noiserejection.SinceMIC_PandMIC_Narehighimpedance
inputs,itisimportanttoisolatethesefrom
possiblenoise
sources(togglingdigitallineswithfastedges).
Thespeakerinterfacecanbesingle‐endedordifferential
dependingonproduct.Single‐endedspeakeroutputsrelyon
modemgroundasanaudioreference.
Theaudiopassbandforbothreceiveandtransmitpaths
(speakerandmicrophone)extendsfrom300Hzto3.4
kHz.A
programmablesidetonewitharangefrommutetounitygain
isavailableforbothheadsetandmainaudiopaths.Sidetone
shouldbemutedforspeakerphoneuse.
Notethatcertaincarriersnowrequireuseofhearing‐aid
compatibletransducersinahandsetdesign.ThePrimary
audiopathcanbeinterfaced
directlytosuchdevices.Referto
ANSIC63.19fordetailsregardingreducedRFemissions(ʺU3
ratingʺ)andinductive/telecoilcoupling(ʺU3Tʺrating)
devices.
Speakerphone
• Long echo path (<64 ms travel time from speaker to
microphone)
• Loud echo
• For use with speakerphone applications with high
distortion
• Half-duplex algorithm, very aggressive in near-end
Tx muting to eliminate transmitted echo
Off
Table 4-3: Echo cancellation details
Mode Details
Table 4-4: Primary audio signal interface
Signal Pin # Type Directions Description
MIC_P
1 Analog Input Non-inverted
microphone input (+)
MIC_N
3 Analog Input Inverted microphone
input (-)