Mixed voltage output driver with automatic impedance adjustment
US6239617A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 4, 1999 |
| Grant date | May 29, 2001 |
| Priority date | — |
| Expiry date | Nov 4, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/0005
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A mixed voltage output driver includes an output sensing circuit that senses an output voltage at an output terminal and generates a voltage signal that corresponds to a voltage level at the output terminal. Next, an impedance selection circuit receives the voltage signal and generates a control signal in response to the output voltage having a higher logical uplevel than the mixed voltage output driver. The control signal is then received by an adjustable drive impedance circuit that is also coupled to an input terminal of the mixed voltage output driver and, in response thereto, the adjustable drive impedance circuit modifies an output drive impedance of the mixed voltage output driver. In another advantageous embodiment, the mixed voltage output driver only determines if the output voltage at the output terminal is at a logical uplevel before adjusting the output drive impedance.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.