TOBY-L2 and MPCI-L2 series - System Integration Manual
UBX-13004618 - R28
Design-in
Page 123 of 164
distribution for WCDMA, taken from operation on a live network, described in the GSMA TS.09 Battery
Life Measurement and Current Consumption Technique
); however the application should be
correctly designed to cope with it.
During transmission at maximum RF power the TOBY-L2 and MPCI-L2 series modules generate
thermal power that may exceed 3 W: this is an indicative value since the exact generated power
strictly depends on operating condition such as the actual antenna return loss, the number of
allocated TX resource blocks, the transmitting frequency band, etc. The generated thermal power
must be adequately dissipated through the thermal and mechanical design of the application.
The spreading of the Module-to-Ambient thermal resistance (R
th,M-A
) depends on the module
operating condition. The overall temperature distribution is influenced by the configuration of the
active components during the specific mode of operation and their different thermal resistance
toward the case interface.
☞
The Module-to-Ambient thermal resistance value and the relative increase of module temperature
will differ according to the specific mechanical deployments of the module, e.g. application PCB
with different dimensions and characteristics, mechanical shells enclosure, or forced air flow.
The increase of the thermal dissipation, i.e. the reduction of the Module-to-Ambient thermal
resistance, will decrease the temperature of the modules’ internal circuitry for a given operating
ambient temperature. This improves the device long-term reliability in particular for applications
operating at high ambient temperature.
Recommended hardware techniques to be used to improve heat dissipation in the application:
Connect each GND pin with solid ground layer of the application board and connect each ground
area of the multilayer application board with complete thermal via stacked down to main ground
layer.
Use the two mounting holes described in
to fix (ground) the MPCI-L2 modules to the
main ground of the application board with suitable screws and fasteners.
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 components included in the application, such 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.
Follow the thermal guidelines for integrating wireless wide area network mini card add-in cards,
such as the MPCI-L2 series modules, as provided in the PCI Express Mini Card Electromechanical
Specification
Further hardware techniques that may be considered to improve the heat dissipation in the
application:
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 cellular
module, as a large part of the heat is transported through the GND pads of the TOBY-L2 series
LGA modules and dissipated over the backside of the application board.
For example, the Module-to-Ambient thermal resistance (R
th,M-A
) is strongly reduced with forced air
ventilation and a heat-sink installed on the back of the application board, decreasing the module
temperature variation.
