DER-36

42W, 4 Output Set Top Box Supply

April 27, 2004

Page 17 of 23

Power Integrations

Tel: +1 408 414 9200 Fax: +1 408 414 9201

www.powerint.com

9

Performance Data

All measurements performed at room temperature, 60 Hz input frequency, unless

otherwise specified.

9.1

Thermal Performance

Thermal measurements were made with the power supply mounted in the chassis, using

a slip-on heat sink on the TOPSwitch. A thermocouple was attached to the heat sink next

to the TOPSwitch source tab using solder. Another thermocouple was soldered to a

length of adhesive-backed copper tape, which was attached to the transformer. A

thermocouple was taped in the center of the chassis, with the junction in free air. This

thermocouple was used to measure the ambient air temperature inside the chassis. All

holes in chassis were sealed with tape except ventilation holes in chassis and holes used

for load and thermocouple wires. A solid cardboard sheet was used as the chassis top

lid. The thermal chamber temperature outside the chassis was adjusted until the desired

temperature was attained inside the chassis. Due to the limited size of the thermal

chamber, the chassis was inserted diagonally into the chamber, with the power supply

side tilted up. This may mean that the local ambient temperature of the supply was higher

than that that measured by the thermocouple, which was located in the chassis center.

The internal ambient temperature was allowed to rise with the unit running at the worst

case power dissipation (e.g. 180VAC) until the unit shutdown (S/D) and the maximum

ambient temperature was then recorded. The device was allowed to cool and restart, and

the thermals measured using the nominal supply voltage at both normal room ambient

and the elevated temperature at which shut down occurred at low line.

Item

180

VAC

230

VAC

230

VAC

Ambient

58

59

23

TOPSwitch (U3)

S/D

122

87

Transformer (T1)

S/D

73

52