
GL865-DUAL V3 Hardware User Guide
1vv0301018 Rev.5 – 2013-08-05
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 45 of 76
Mod. 0805 2011-07 Rev.2
If the audio source is not a mike but a different device, the following connections can be done.
Place a 1Kohm resistor to ground on the negative input, in order to get balanced the input;
than connect the source via 1uF capacitor, so the DC current is blocked.
Since the input is differential, the common mode voltage noise between the two (different)
grounds is rejected, provided that both AF_IN+ & AF_IN- are connected directly onto the
source.
1u
220n
220n
1K
1K
1u
1u
AF_IN+
MIC/AF_IN+
MIC/AF_IN-
AGND
MODULE
-
+
INPUT
ADC
Vmic
Remote_GND