User's Manual

GE/GC864-QUAD V2 and GE864-GPS Hardware User Guide

1vv0300915 Rev.2 – 2011-06-15

Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights

Reserved. Page 69 of 97

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 16Ω load at –

12dBFS (**) in Differential configuration

• the “Ear_HF” lines can directly drive a 4Ω 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

differential