Hardware

Environmental Specifications
A DIVISION OF TRIMBLE
Hardware Overview 29
Environmental Specifications
Thermal Considerations
There are two ways of mounting the Micro, see Micro Hardware Integration for additional
details. One is to solder the board to the motherboard using its side “vias”, with the RF
shield can facing upward. The other is to use the board-to-board connectors to connect to
the motherboard and solder the 4 tabs on the shield to the motherboard as well. The
orientation with the side “vias” soldered down is best for wicking heat away from the
module.
Most applications involve the module transmitting periodically to inventory tags in the
field. The longer the transmitter is on in relation to its off time (the “duty cycle”) the faster
the temperature will rise. The module will not transmit if the temperature is at a dangerous
level, but will transmit again as soon as the temperature drops – often so quickly it is
hardly noticeable. Other factors that affect the time before the module begins to protect
itself is the ambient temperature and the power level at which the module is transmitting.
These factors are represented in the following table, which give the typical minutes of
transmission time before thermal protection is enabled:
Thermal Calculations
Mounting
Ambient
Temp (°C)
RF Power
(dBm)
Duty Cycle
%
Time (m) to reach
max temperature
Soldered down -40 30 98 No restriction
Soldered down 25 23 98 No restriction
Soldered down 25 30 80 No restriction
Soldered down 25 30 90 7.34
Soldered down 25 30 98 5.99
Soldered down 60 23 50 No restriction
Soldered down 60 23 60 7.59
Soldered down 60 23 80 2.24
Soldered down 60 23 98 1.46
Soldered down 60 30 30 No restriction
Soldered down 60 30 50 4.17