u-blox SARA-G3 Series User Manual

SARA-G3 series - System Integration Manual
UBX-13000995 - R06 Objective Specification Design-in
Page 156 of 218
 Provide a ground plane as wide as possible on the application board
 Optimize antenna return loss, to optimize overall electrical performance of the module including a
decrease of module thermal power
 Optimize the thermal design of any high-power component included in the application, as linear
regulators and amplifiers, to optimize overall temperature distribution in the application device
 Select the material, the thickness and the surface of the box (i.e. the mechanical enclosure of the
application device that integrates the module) so that it provides good thermal dissipation
 Force ventilation air-flow within mechanical enclosure
 Provide a heat sink component attached to the module top side, with electrically insulated / high
thermal conductivity adhesive, or on the backside of the application board, below the wireless module
For example, after the installation of a robust aluminum heat-sink with forced air ventilation on the back
of the same application board described above, the Module-to-Ambient thermal resistance (Rth,M-A) is
reduced up to the Module-to-Case thermal resistance (Rth,M-C) defined in the SARA-G3 series Data
Sheet [1]. The effect of lower Rth,M-A can be seen from the module temperature increase, which now can
be summarized as following:
 ~1 °C during a GSM voice call (1 TX slot, 1 RX slot) at the maximum TX power
 ~2 °C during a GPRS data transfer (2 TX slots, 3 RX slots) at the maximum TX power
Beside the reduction of the Module-to-Ambient thermal resistance implemented by the hardware design of
the application device integrating a SARA-G3 series module, the increase of module temperature can be
moderated by the software implementation of the application.
Since the most critical condition concerning module thermal power occurs when module connected-mode is
enabled, the actual module thermal power depends, as module current consumption, on the radio access
mode (GSM / GPRS), the operating band and the average TX power.
A few software techniques may be implemented to reduce the module temperature increase in the
application:
 Select by means of AT command (refer to the u-blox AT Commands Manual [2][2], +UCLASS
command) the module’s GPRS multi-slot class which provides lower current consumption (refer to
current consumption values reported in the SARA-G3 series Data Sheet [1][1])
 Select by means of AT command (refer to the u-blox AT Commands Manual [2][2], +UBANDSEL
command) the operating band which provides lower current consumption (refer to current consumption
values reported in the SARA-G3 series Data Sheet [1][1])
 Enable module connected-mode for a given time period and then disable it for a time period enough
long to properly mitigate temperature increase
Formatted: English (U.S.), Hidden
Formatted: English (U.S.)
Formatted: English (U.S.)
Formatted: English (U.S.)
Formatted: English (U.S.)

u-blox SARA-G3 Series Specifications

General

Brand	u-blox
Model	SARA-G3 Series
Category	GSM/GPRS Modules
Language	English