DER-36 Datasheet, PDF (18/23 Pages) Power Integrations, Inc. – 42W, 4 Output Supply using TOP245Y

DER-36
42W, 4 Output Set Top Box Supply
April 27, 2004
10 Waveforms
10.1 12V Output Turn Off
The waveforms shown below were taken with output loads set to 5V/4A, 6.8V/1.5A, and
12V/0.5A, with a fixed 100 ohm resistor on the –10V output. The 5V and 12V outputs
were monitored with an oscilloscope. The oscilloscope was triggered on the falling edge
of the 5V output. The waveforms show the rise in the lightly loaded 12V output just before
the heavily loaded +5V output goes out of regulation after removal of AC power. Use of a
heavy foil on the transformer secondaries, along with a small ferrite bead in series with
the 12V rectifier, keeps the 12V overshoot within 5%. The ferrite bead also helps to
center the 12V output.
Figure 5 - 180 VAC, 5V/4A, 12V/0.5A, 6.8V/1.5A,
10msec/div
Upper: 12V, 2V / div
Lower: 5V, 1V / div
Figure 6 - 230 VAC, 5V/4A, 12V/0.5A, 6.8V/1.5A,
10msec/div
Upper: 12V, 2V / div
Lower: 5V, 1V / div
Page 18 of 23
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