Multiple output switching power supply having one controlled output voltage and load compensation

• US 4,999,759 A
• Filed: 07/20/1990
• Issued: 03/12/1991
• Est. Priority Date: 09/27/1989
• Status: Expired due to Fees

• Current Assignee: Alessandro Scotti, Gian P. Cavagnolo
• Original Assignee: Alessandro Scotti, Gian P. Cavagnolo
• Inventors: Scotti, Alessandro, Cavagnolo, Gian P.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): VOELTZ, EMANUEL T
• Application Number:
  US07/556,608
• Time in Patent Office: 235 Days
• Field of Search: 323/266, 323/267, 363/20, 363/21, 363/24, 363/25, 363/95, 363/97, 363/131, 363/134, 307/12, 307/17, 307/31-35, 307/38, 307/39
• US Class Current: 363/21.01
• CPC Class Codes: H02M 1/009 having two or more independently controlled outputs for DC-DC converter with intermediate AC H02M3/33561
• CPC Class Codes: H02M 3/33561 having more than one ouput with independent control

Abstract

A multiple output switching power supply having one controlled output and load compensation, where periodical voltage pulses, induced in at least two secondary windings of a transformer, load two buffer capacitive elements, each connected between ground and, respectively a first and a second output terminal at two different, like sign voltages and makes available two output voltages V1, V2, one of which (V1) is controlled, at first and second output terminals, respectively, and where the capacitive element connected between ground and the first terminal includes two series connected capacitors having respective values such that a voltage slightly higher than V2 in absolute value is imparted to the node common to the two capacitors. The node is connected to the second output terminal through a diode conductive in the direction which allows the electric charge stored in the first capacitive element to flow towards the second terminal and the second capacitive element when the output voltage V2 decreases in absolute value.

Claims

1. A multiple output switching power supply providing a first directly controlled output voltage between a first output and ground and indirect control of at least a second output voltage between a second output and ground, comprising a transformer having at least a primary winding and at least two secondary windings, periodical voltage pulses being induced in said secondary windings, said voltage pulses loading, through rectifying elements, a first capacitive element, having a grounded terminal, at a first voltage V1 and a second capacitive element, having a grounded terminal, at a voltage V2 having the same polarity as V1 but having a lower value, said voltages being available, for powering loads, respectively at said first output and at said second output, said power supply being characterized in that:

said first capacitive element comprises a first and a second capacitor, series connected between said first output and ground, the node common to said first and said second capacitor being connected to said second output through a diode, said first and second capacitors having a value such that said first voltage applies to said node a voltage level equal or slightly higher, in absolute value, than said second voltage, said diode being conductive in the direction which allows power flow from said first capacitive element to said second output terminal and said second capacitive element.

2. A power supply as in claim 1 further comprising a resistor connected between said first output and said node common to said first and second capacitor.