AN904 Datasheet | STMicroelectronics

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 pact and reliable switching power supplies has aroused renewed interest 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 plexity of conventional switching regulators. In cases where the load currents of the subordinate outputs are high ( more than 2 - 3 Amps ), the advantages of the saturable regulators bee more significant. Figure 1. Multiple-Output Switched-Mode Power Supplies. FEEDBAK + V+ MAIN Vout + REGULATOR AUXILIAR 1 Vout PWM DRIVER + REGULATOR AUXILIAR 2 Vout - December 1997 1/3 AN904 APPLICATION NOTE Figure 2. FEEDBAK + V+ CR2 MAIN Vout - SR CR1 L4 Rsense + CR2 PWM DRIVER +6 AUXILIARY Vout 1 8 CR3...