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Browse Prior Art Database

Isolated, Remote Power Supply "on" Control

IP.com Disclosure Number: IPCOM000042593D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Celenza, N: AUTHOR [+2]

Abstract

This circuit allows remote turn-on of a power supply through a transformer-isolated primary/secondary interface with no secondary standby power. In the figure, with switch S1 open, the current through resistor R1 is limited by the magnetizing inductance of primary 1 of transformer T1. Accordingly, there is never enough voltage at node 2 to trigger the threshold detector. Closing S1 shorts secondary 3 of T1 and changes the inductance of primary 1 from the relatively high magnetizing inductance to a relatively low leakage inductance, resulting in considerably higher current through R1 per cycle of the oscillator. The higher current in R1 provides a sufficient voltage at node 2 to trigger the threshold detector which then provides pulses along line 4.

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Isolated, Remote Power Supply "on" Control

This circuit allows remote turn-on of a power supply through a transformer- isolated primary/secondary interface with no secondary standby power. In the figure, with switch S1 open, the current through resistor R1 is limited by the magnetizing inductance of primary 1 of transformer T1. Accordingly, there is never enough voltage at node 2 to trigger the threshold detector. Closing S1 shorts secondary 3 of T1 and changes the inductance of primary 1 from the relatively high magnetizing inductance to a relatively low leakage inductance, resulting in considerably higher current through R1 per cycle of the oscillator. The higher current in R1 provides a sufficient voltage at node 2 to trigger the threshold detector which then provides pulses along line 4. The pulses on line 4 trigger the power supply primary control circuitry to initiate starting of the power supply.

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