Method and apparatus for communicating with a host
US6543690B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Dec 4, 2000 |
| Grant date | Apr 8, 2003 |
| Priority date | — |
| Expiry date | Jun 27, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F13/4086
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus is disclosed for communicating with a host. In one embodiment, a smart card has an IC with voltage conditioning circuitry and a pull-up resistor. The smart card, when inserted in a smart card reader coupled to the host, is capable of signaling the host over a bus using the pull-up resistor selectively coupled to a voltage output of the voltage conditioning circuitry and a first output of the smart card. The voltage conditioning circuitry output is selectively coupled to the first output through the resistor, responsive to the device being powered by the bus but not transmitting. This tends to pull up the first output to the voltage level of the voltage source, which makes the smart card capable of being properly detected by the host upon the bus being driven by a host. Selectively disconnecting the pull-up resistor while the smart card is transmitting or receiving results in a more balanced differential output signal. Since the pull-up resistor and voltage conditioning circuitry supplying the proper voltage to the pull-up resistor are an integrated part of the IC, no separate contact is required to supply voltage to the resistor. This permits the smart card t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.