DER-19

TOP245P Multiple Output Set Top Box

March 30, 2004

Page 18 of 25

Power Integrations, Inc.

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

www.powerint.com

10 Thermal Performance

At full continuous output power, the temperature of key components was monitored using

thermocouples. In a 25°C ambient, Figure 11 gives the resulting temperature profiles.

0

10

20

30

40

50

60

70

80

90

100

180

200

220

240

260

280

Line Voltage (Vrms)

TOP245P

Transformer

3V3 Diode

5V Diode

Ambient

Figure 11 - Key Component Temperature Rise variation with Line Voltage

All key components are operating well within specified temperature ranges and this

design would support operation in ambient levels up to 50°C.

11 Waveforms

11.1 Drain Voltage and Current, Normal Operation

µs /

div

Figure 13 - 265 VAC, Full Continuous Load