User's Manual

GE864
GE864GE864
GE864-
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-QUAD Automotive V2 Hardware User Guide
QUAD Automotive V2 Hardware User GuideQUAD Automotive V2 Hardware User Guide
QUAD Automotive V2 Hardware User Guide
1vv0300840 Rev.3 2010-04-08
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 45 of 71
10.2.
10.2.10.2.
10.2. Electrical Characteristics
Electrical CharacteristicsElectrical Characteristics
Electrical Characteristics
TIP:
TIP: TIP:
TIP: Being the microphone circuitry the more noise sensitive, its design and layout
must be done with particular care. Both microphone paths are balanced and the OEM
circuitry must be balanced designed to reduce the common mode noise typically
generated on the ground plane. However the customer can use the unbalanced
circuitry for its particular application.
10.2.1.
10.2.1.10.2.1.
10.2.1. Input Lines Characteristics
Input Lines CharacteristicsInput Lines Characteristics
Input Lines Characteristics
“MIC_MT” and “MIC_HF” differential microphone paths
“MIC_MT” and “MIC_HF” differential microphone paths“MIC_MT” and “MIC_HF” differential microphone paths
“MIC_MT” and “MIC_HF” differential microphone paths
Line Coupling AC*
Line Type Balanced
Differential input voltage
≤ 1,03V
pp
@ Mic G=0dB
Gain steps
Gain stepsGain steps
Gain steps 7
Gain increment 6dB per step
Coupling capacitor
≥ 100nF
Differential input
Differential input Differential input
Differential input
resistance
resistanceresistance
resistance
50KΩ
Input capacitance • 10pF
(*) WARNING :
(*) WARNING : (*) WARNING :
(*) WARNING : AC means that the signals from the microphone have to be connected
to input lines of the module through capacitors which value has to be ≥ 100nF. Not
respecting this constraint, the input stages will be damaged.
WARNING:
WARNING: WARNING:
WARNING: when particular OEM application needs a Single Ended Input configuration,
it is forbidden connecting the unused input directly to Ground, but only through a 100nF
capacitor. Don’t forget that the useful input signal will be halved in Single Ended Input
configuration.