Browse Prior Art Database

Rc Oscillator

IP.com Disclosure Number: IPCOM000036821D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 4 page(s) / 99K

Publishing Venue

IBM

Related People

Frushour, JE: AUTHOR [+3]

Abstract

An oscillator is shown and described herein that is programmable for frequency and pulse width with an external resistor and capacitor. It can be operated in parallel with the same type of oscillators by connecting SYNC lines together. The oscillator is usable over a wide range of frequencies, from less than 1 Hz to 5 MHz, and operates with a wide range of power supply voltages. (Image Omitted)

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Rc Oscillator

An oscillator is shown and described herein that is programmable for frequency and pulse width with an external resistor and capacitor. It can be operated in parallel with the same type of oscillators by connecting SYNC lines together. The oscillator is usable over a wide range of frequencies, from less than 1 Hz to 5 MHz, and operates with a wide range of power supply voltages.

(Image Omitted)

A positive-going ramp is input into a comparator 10 (Fig. 1) that is referenced to voltage VR1. When the ramp crosses this reference voltage, the reference to the comparator 10 is dropped to a lower voltage VR2 and a short time later the ramp goes negative. When the ramp crosses the lower reference, the reference is raised again to the higher voltage VR1 and the cycle is repeated.

The reference voltage input to the comparator 10 is formed by a resistor divider comprising R1 and R2 (Fig. 2). This voltage is set for VR1 volts. A positive ramp voltage is generated by a current source 12 charging external program capacitor C. This ramp is input to the other leg of the comparator 10.

The comparator 10 switches when the ramp voltage becomes slightly greater than VR1 reference. This causes current switches 14, 16 and 18 to turn on. When the first switch 14 turns on, the reference volt

(Image Omitted)

age on the comparator input drops to VR2 volts. When the third switch 18 is activated, the voltage across C ramps down toward VR2.

The third current switch 18 discharge...