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Positive to Negative Voltage Converter

IP.com Disclosure Number: IPCOM000061124D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Langer, P: AUTHOR

Abstract

This article describes a circuit arrangement which generates a negative voltage from a positive source.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 90% of the total text.

Page 1 of 1

Positive to Negative Voltage Converter

This article describes a circuit arrangement which generates a negative voltage from a positive source.

Portable electronic products are frequently constrained to a single polarity power source (i.e., battery). In cases which require a negative voltage source, it is necessary to generate that voltage from the positive source. The circuit arrangement disclosed herein generates a negative voltage from a positive source by the use of an astable multivibrator as a charge pump, two steering diodes and two capacitors.

The present circuit arrangement is shown in the drawing. The astable multivibrator must have a push/pull output and must be capable of providing all the voltage and current required by the output load at V-. On the positive side of the cycle of the astable multivibrator output capacitor C1 discharges through diode CR1 to ground leaving the positive side of the capacitor at one diode drop above ground. Diode CR2 is reverse biased and blocks current flow into C2. On the negative side of the cycle the node at the junction of CR1, CR2, and C1 becomes negative. Since CR1 is reverse, current cannot flow through it. However, CR2 is forward biased and conducts until capacitor C2 is negative enough to cause diode CR2 to turn off. Capacitor C2 is an integrating capacitor whose voltage ends up being opposite in polarity but of equal magnitude to the astable multivibrator output minus two diode drops.

A typical application for t...