GE/GC864-QUAD V2 and GE864-GPS Hardware User Guide
1vv0300915 Rev.5 – 2011-10-03
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved.
Page 42 of 94
6.3.2.
Thermal Design Guidelines
The thermal design for the power supply heat sink must be done with the following
specifications:
Average current consumption during transmission @PWR level max: 500mA
Average current consumption during transmission @ PWR level min: 100mA
Average current during Power Saving (CFUN=5): from 1.5 to 3.9mA
Average current during idle (Power Saving disabled): 16mA
NOTE:
The average consumption during transmissions depends on the power level at which the
device is requested to transmit by the network. The average current consumption hence varies
significantly.
Considering the very low current during idle, especially if Power Saving function is enabled,
it is possible to consider from the thermal point of view that the device absorbs current
significantly only during calls.
If we assume that the device stays into transmission for short periods of time (let us say few
minutes) and then remains for a quite long time in idle (let us say one hour), then the power
supply has always the time to cool down between the calls, and the heat sink could be smaller
than the calculated one for 500mA maximum RMS current, or even could be the simple chip
package (no heat sink).
Moreover, in the average network conditions, the device is requested to transmit at a lower
power level than the maximum, hence the current consumption will be less than 500mA,
usually around 150mA.
For these reasons the thermal design is rarely a concern and the simple ground plane where
the power supply chip is placed grants a good thermal condition to avoid overheating as well.
As far as the heat generated by GC/GE864-QUAD V2 and GE864-GPS , you can consider it
to be during transmissions of 1W max during CSD/VOICE calls and 2W max during class10
GPRS upload.
This generated heat will be mostly conducted to the ground plane under GC/GE864-QUAD
V2 AND GE864-GPS ; you must ensure that your application can dissipate it.
