AN904 Datasheet, PDF (1/3 Pages) STMicroelectronics – MAGNETIC AMPLIFIER WITH LPR30 CONTROLLER

AN904
APPLICATION NOTE
MAGNETIC AMPLIFIER WITH LPR30 CONTROLLER
by F. Lentini & T. Sampieri
Proper regulation is important in multiple output power supplies where the individual outputs must be
tightly controlled.
The continuing need for more compact and reliable switching power supplies has aroused renewed in-
terest in a well founded control technique: THE MAGNETIC AMPLIFIER.
THE MAGNETIC AMPLIFIER ( shortly written MAG -AMP ), means higher density, simpler control circuit
and higher running frequency in Switching Power Supply.
The MAG AMP is suitable for controlling individual outputs ranging from a few watts to over 100 watts in
power converters whose frequencies range from 20KHz to several hundred KHz.
Picture 1 shows the best application of the MAG AMP is in the Switched - Mode Power Supplies .
By using such a square - loop core to provide a controllable delay at the leading edge of the pulses at
the secondary of the transformer, one or more outputs can be independently and precisely regulated
without the losses inherent in linear regulators or the complexity of conventional switching regulators. In
cases where the load currents of the subordinate outputs are high ( more than 2 - 3 Amps ), the advan-
tages of the saturable regulators become more significant.
Figure 1. Multiple-Output Switched-Mode Power Supplies.
V+
PWM
DRIVER
FEEDBAK
CR
CR
REGULATOR
CR
REGULATOR
December 1997
+
MAIN Vout
-
+
AUXILIAR 1
Vout
-
+
AUXILIAR 2
Vout
-
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