7-Feb-2006
EP-91 12 V, 1 A, Universal Input Supply
10 Thermal Performance
Temperature measurements of key components were taken using T-type thermocouples.
The thermocouples were soldered directly to a SOURCE pin of the TNY278P device and
to the cathode of the output rectifier. The thermocouples were glued to the output
capacitor and to the external core and winding surfaces of transformer T1.
The unit was sealed inside a large box to eliminate any air currents. The box was placed
inside a thermal chamber. The ambient temperature within the large box was raised to
50 °C. The unit was then operated at full load and the temperature measurements were
taken after they stabilized for 1 hour at 50 °C.
Temperature (°C)
Item
85 VAC 265 VAC
Ambient
50*
50*
92.8
80
TNY278P (U1)
96.1
77.8
101
68.2
Transformer (T1)
Output Rectifier (D7)
Output Capacitor (C10)
100
66.8
*To simulate operation inside sealed enclosure at 40 °C external ambient.
These results show that all key components have an acceptable rise in temperature.
85 VAC, 12 W Load, 22 °C Ambient
Figure 11 – Infrared Thermograph of Open Frame Operation, at Room Temperature.
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