Rev. 4.0 5/22/2010
International Rectifier
Page 15 of 16
PROPRIETARY INFORMATION - This document and the information contained therein are proprietary and are not to be reproduced, used or disclosed
to others for manufacture or any other purpose except as specifically authorized in writing by
INTERNATIONAL RECTIFIER.
The average efficiency of the board at 25%, 50%, 75% and 100% load is 92% at 270Vac input:
90.5%
91.0%
91.5%
92.0%
92.5%
93.0%
93.5%
50.0
70.0
90.0
110.0 130.0 150.0 170.0 190.0 210.0
E
ff
ic
ie
n
cy
Output Power (W)
Efficieny vs. Output Power
400Vdc input
270Vac input
Figure 8 - Efficiency plot
5.6 Thermal Data
The thermal performance of IRS27951 demo board is tested at 400Vdc input and 220W full load under room
temperature.
Part
Case Temperature (°C)
MOSFET Q1
44.5
MOSFET Q2
42.5
U1 IRS27951
41
Transformer
73
24V diodes
72
12V diodes
60
6 Transformer Spec
Core type: ETD49 - 0R44949EC
Minimum operating frequency: 80 kHz
Primary inductance: 585 µH
±
10% @1 kHz - 0.25V (
Note 1
)
Leakage inductance: 125 µH
±
10% @1 kHz - 0.25V (
Note 2
)
Note: 1 Measured between Pins 2 and 5
Note: 2 Measured between Pins 2 and 5 with secondary windings shorted