On-chip frequency trimming method for real-time clock
US5327404A · kind A · utility
14Cited by
7References
18Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Nov 27, 1990 |
| Grant date | Jul 5, 1994 |
| Priority date | — |
| Expiry date | Nov 27, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG04G3/02
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for digitally trimming the output frequency of a real-time clock is disclosed. The output frequency of a divider chain is adjusted by the contents of a trim constant register. The amount of correction and direction (slow or fast) to be effected is determined by the trim constant register. During "slow" real-time clock operation, the divider chain "shortens" the next second produced by the real-time clock. During "fast" real-time clock operation, the production of the next second is blocked and then a portion of the "blocked" signal is "added back" to effectively "lengthen" the next second produced by the real-time clock.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.