ThingMagic Micro Hardware - Manual (Page 31)

Environmental Specifications
A D I V I S I O N O F T R I M B L E
Hardware Overview 31
Thermal Management
Heatsinking
For high duty cycles, it is essential to use the surface mount configuration - as shown in
Micro Hardware Integration | Sample Board Layout Using Surface Mount Option - where all
edge vias are soldered to a carrier or mother board, with a large area of ground plane,
that will either radiate heat or conduct the heat to a larger heatsink. A high density of PCB
vias from the top to bottom of the board will efficiently conduct heat to a bottom mount
heatsink. Often the weak link in thermal management design is not the thermal interface
from the Micro to the heatsink, but rather the thermal interface from the heatsink to the
outside world.
Duty Cycle
In comparison to many RFID modules, including the M5e, the Micro has much higher
performance capabilities when running at comparable duty cycles. As such, very high
duty cycles are often not necessary to meet performance requirements with the Micro. If
overheating occurs it is recommended to first try reducing the dutycyle of operation. This
involves modifying the RF On/Off (API parameter settings /reader/read/asyncOnTime and
asyncOffTime) values. A good place to start is 50% duty cycle using 250ms/250ms On/
Off.
If your performance requirements can be met, a low enough duty cycle can result in no
heat sinking required. Or with adequate heat sinking you can run continuously at 100%
duty cycle.
Thermal Resistance
The measured thermal resistance from the on-board temperature sensor to the top
ground plane of surface mount carrier board is approximately 4.8°C per watt. This roughly
translates to supporting 100% duty cycle if the carrier board is maintained at 52°C or less.