Autonomous selection of output buffer characteristics as determined by load matching
US5677639A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 8, 1994 |
| Grant date | Oct 14, 1997 |
| Priority date | — |
| Expiry date | Dec 8, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/0005
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A mechanism determines at least an approximation of output load coupled to a programmable output buffer, and then programs the buffer to source/sink an amount of output current appropriate to the load to be driven. The mechanism includes a load recognition unit, an optional signal conditioner, and a reconfiguration logic module. In interface-governed applications, the load recognition unit senses an interface bit (AT Attachment interface), or causes the output buffer to act as a master unit that polls the interface connection to determine the number of attached loads (SCSI interface). The recognition unit then outputs a signal that may be conditioned before being input to a reconfiguration logic module that outputs appropriate control signals that program the buffer. Alternatively, the load recognition unit may measure the shunt capacitance associated with the load by using a reference current source and an analog/digital converter. The resultant voltage developed across the shunt capacitance provides a measure of the load impedance, which is used by the reconfiguration logic module to output control signals appropriately configuring the output buffer. Preferably the output buffer …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.