EPR-91 datasheet(23/36 Pages) POWERINT

23 / 36 page

7-Feb-2006

EP-91 12 V, 1 A, Universal Input Supply

Page 23 of 36

Power Integrations

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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

°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

TNY278P (U1)

96.1

92.8

Transformer (T1)

77.8

Output Rectifier (D7)

101

100

Output Capacitor (C10)

68.2

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.

EPR-91 Datasheet(PDF) 23 Page - Power Integrations, Inc.