Precision crystal oscillator circuit used in microcontroller
US6563391B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 25, 2001 |
| Grant date | May 13, 2003 |
| Priority date | — |
| Expiry date | Apr 25, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K3/02315
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A microcontroller is disclosed that includes a crystal oscillator circuit that is programmable to provide multiple different levels of startup current. In the present embodiment, the crystal oscillator circuit includes logic devices for receiving programming indicating one of a plurality of different startup current levels and a resistor chain. The logic devices are coupled to the resistor chain for controlling the resistance of the oscillator circuit such that, upon receiving programming indicating a particular startup current level, the crystal oscillator circuit generates a corresponding startup current. In addition, the crystal oscillator circuit includes provision for selecting one of a plurality of different levels of capacitance. Furthermore, the crystal oscillator circuit includes a pass gate that includes circuitry for assuring predetermined startup conditions are met. A feedback loop that includes an amplifier provides for steady-state operations that have low power consumption.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.