EPR-71 Datasheet, PDF (20/28 Pages) Power Integrations, Inc. – Engineering Prototype Report for EP 71 - 6.6 W DC-DC Converter Using DPA Switch- (DPA423G)

EP-71 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
11 Thermal Performance
The temperatures of key components were recorded using T-type thermocouples. Two
of the four thermocouples were soldered, one directly to a SOURCE pin of the DPA423G
(U1) and the other to the cathode of the output rectifier (D1). The other two
thermocouples were glued, one to the transformer (T1) core on the center leg, and the
other to the case of the first of the two high-ripple output capacitors (C7).
The unit was operated at full load, at 36 VDC, 48 VDC and 57 VDC in free convection
within a small enclosure to prevent external air currents affecting the measurements.
The results show adequate thermal margin, considering an additional ambient rise of
+29 °C. At 36 VDC, full load, within an enclosure at elevated 50 °C ambient, this equates
to a DPA423G case temperature of 79 °C. This is well below the recommended
maximum case temperature of 100 °C.
An infrared measurement taken at nominal-line (48 VDC) is provided.
Measured Temperature (°C)
Item
36 VDC 48 VDC 57 VDC
Ambient
21
21
21
DPA423G (U1)
50
49
49
Transformer core (T1) 75
74
74
Output Rectifier (D1)
66
64
64
Output Capacitor (C7) 42
41
42
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