EPR-00011 - 70 W Adapter 22-Jan-01
Page 22 of 46
Power Integrations Inc
Tel: +1 408 414 9200 Fax: +1 408 414 9201
ww: http://www.powerint.com
Figure 12 - Schematic cross-section of enclosure
Note: The diagram above shows an exploded view. In actual construction,
there are no air gaps between the board, copper heat spreader and case.
The main path for heat dissipation is via conduction therefore air gaps,
even small, greatly increase the thermal impedance from the heatsinks to
ambient. Air gaps will reduce power capability and increase the
temperature of components.
Thermal Results in Enclosure
0
20
40
60
80
100
120
140
0 2 4 6 8 10 12 14 16 18
Elapsed Time (Hours)
Temperature (deg. C)
Top249 tab Bridge CM Choke Bulk/Xcap Opto
Enc. Top Enc. Side Snubber T-former D5 tab
D1 tab Ambient 1 Ambient 2
Figure 13 - Thermal results in enclosure at elevated ambient with 60, 65,70, and 72.5 Watt loads – 90 V
AC
72.5 W70 W
65 W
60 W
