User's Guide

Review Copy 11-6-10
ThingMagic Micro Family Guide
9
www.JADAKtech.com
Thermal Calculations (Continued)
Mounting
Ambient
Temp (°C)
RF Power
(dBm)
Duty Cycle
%
Time (m) to reach
max temperature
Board to board
25
23
98
1.24
Board to board
25
30
40
No restriction
Board to board
25
30
50
6.68
Board to board
25
30
60
2.49
Board to board
25
30
80
1.5
Board to board
25
30
98
1.06
Board to board
60
23
30
5.64
Board to board
60
23
50
1.13
Board to board
60
23
60
0.81
Board to board
60
23
80
0.54
Board to board
60
23
98
0.29
Board to board
60
30
15
No restriction
Board to board
60
30
30
1.98
Board to board
60
30
50
0.73
Board to board
60
30
60
0.56
Board to board
60
30
80
0.27
Board to board
60
30
98
0.27
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 side-pads 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 side-pads 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, the Micro has much higher read rate 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, try reducing the duty cycle of operation. This involves modifying the RF
On/Off (API parameter settings /reader/read/asyncOnTime and asyncOffTime) values. Start with 50% duty
cycle using 250ms/250ms On/ Off.