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Table 6.1-1: Power and Temperature dissipation
Component
Name
Designation
Number
Power
Thermal
resistance
θ
θ
θ
θ
jc
Case
temperature
Junction
temperature
Tj/Ta
allowable
max
[W]
[C/W]
[C]
[C]
[C]
1 Flash
U5-U12,
U105-U112
0.04
51
71
71
Tj=125
2 E3
U3
0.162
18.2
71
74
Tj=125
3 TI-transceiver
U1-U4,
U101-U104
0.0025
71
-
Ta=85
4 DC-DC
U2
0.01
70.7
Ta=85
5 Oscillator
Y1
0.018
70.5
Ta=70
7
Conclusions
•
The design is reasonable, the components are within their max allowable
temperature.
•
The unit is very dense, all major gap (card to card, card to structure), are closed
by thermal pads.
•
Due to small power consumption, less then 1 w, and the small thermal density,
there are no major hot spots on the system.
•
Whenever the allowable junction temperature and thermal resistance are known,
the junction temperature is used as the allowable criterion. For other cases the
maximum ambient is used.
•
The maximum ambient temperature inside the module is about 71°C.
