GE863 Datasheet, PDF (15/69 Pages) List of Unclassifed Manufacturers – Telit GE863-QUAD / GE863-PY Hardware User guide

Telit GE863-QUAD / GE863-PY
Hardware User guide
1vv0300697, Rev. ISSUE#0, - 21/11/05
NOTE: For all the threshold voltages, inside the GE863-QUAD all threshold are fixed in order to
maximize Li-Ion battery performances and do not need to be changed.
NOTE: In this application the battery charger input current must be limited to less than 400mA. This
can be done by using a current limited wall adapter as the power source.
3.2.2 Thermal Design Guidelines
The thermal design for the power supply heat sink should be done with the following
specifications:
• Average current consumption during transmission @PWR level max (rms): 500mA
• Average current consumption during transmission @ PWR level min (rms): 100mA
• Average current during Power Saving:
4mA
• Average current during idle (Power Saving disabled)
19mA
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.
TIP: The thermal design for the Power supply should be made keeping a average consumption at
the max transmitting level during calls of 500mA rms.
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's say few
minutes) and then remains for a quite long time in idle (let's 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 and hence the current consumption will be less than the 500mA, being
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 can be enough to ensure a good thermal condition and avoid
overheating.
For the heat generated by the GE863-QUAD, you can consider it to be during transmission 1W
max during CSD/VOICE calls and 2W max during class10 GPRS upload.
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