User's Manual

GC864 Hardware User Guide
1vv0300874 Rev.0 – 2010-01-25
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved. Page 44 of 64
10.2.2. Output Lines Characteristics
TIP:
We suggest driving the load differentially from both output drivers, thus the output
swing will double and the need for the output coupling capacitor avoided. However if
particular OEM application needs also a
Single Ended circuitry can be implemented,
but the output power will be reduced four times .
The OEM circuitry shall be designed to reduce the common mode noise typically
generated on the ground plane and to get the maximum power output from the
device (low resistance tracks).
WARNING:
The loads are directly connected to the amplifier outputs when in Differential
configuration, through a capacitor when in Single Ended configuration.
Using a
Single Ended configuration , the unused output line must be left open .
Not respecting this constraint, the output stage will be damaged.
TIP :
Remember that there are slightly different electrical performances between the two
internal audio amplifiers:
• the
“Ear_MT” lines can directly drive a 16 Ω load at –12dBFS (**) in
Differential configuration
• the “
Ear_HF” lines can directly drive a 4 Ω load in Differential configurations
• There is no difference if the amplifiers drive an external amplifier
(**)
0dBFS is the normalized overall Analog Gain for each Output channel equal to
3,7V
pp
differential