Claims
- 1. Pullup circuitry for an open-drain signal line, the pullup circuitry comprising:circuitry for monitoring a slew rate of a signal on the open-drain signal line; circuitry for providing a pullup current to the open-drain signal line responsive to the monitored slew rate exceeding a slew rate threshold; and circuitry for increasing the pullup current responsive to a voltage level of the signal.
- 2. Pullup circuitry for an open-drain signal line, the pullup circuitry comprising:circuitry for monitoring a slew rate of a signal on the open-drain signal line; circuitry for providing a pullup current to the open-drain signal line responsive to the monitored slew rate exceeding a slew rate threshold, wherein the circuitry for providing the pullup current comprises first circuitry for providing a first current independent of the monitored slew rate, and second circuitry for providing a second current responsive to the monitored slew rate; and circuitry for increasing the pullup current responsive to a voltage level of the signal.
- 3. The pullup circuitry of claim 2 wherein the pullup current is increased responsive to the voltage level exceeding a voltage threshold, and wherein the increase in pullup current is a function of the voltage level relative to the voltage threshold.
- 4. Pullup circuitry for an open-drain signal line, the pullup circuitry comprising:circuitry including an operational amplifier for monitoring a slew rate of a signal on the open-drain signal line; circuitry for providing a pullup current to the open-drain signal line responsive to the monitored slew rate; and circuitry for increasing the pullup current responsive to a voltage level of the signal.
- 5. Pullup circuitry for an open-drain signal line, the pullup circuitry comprising:circuitry including an operational amplifier for monitoring a slew rate of a signal on the open-drain signal line; circuitry for providing a pullup current to the open drain signal line responsive to the monitored slew rate, wherein the circuitry for providing the pullup current comprises first circuitry for providing a first current independent of the monitored slew rate, and second circuitry for providing a second current responsive to the monitored slew rate; and circuitry for increasing the pullup current responsive to a voltage level of the signal.
- 6. The pullup circuitry of claim 5 wherein the pullup current is increased responsive to the voltage level exceeding a voltage threshold, and wherein the increase in pullup current is a function of the voltage level relative to the voltage threshold.
- 7. The pullup circuitry of claim 6 wherein the pullup current is increased responsive to the monitored slew rate exceeding a slew rate threshold.
- 8. The pullup circuitry of claim 4 wherein the circuitry for monitoring the slew rate is a differentiator.
- 9. A method for biasing an open-drain signal line, the method comprising:monitoring a slew rate of a signal on the signal line; providing a pullup current to the signal line responsive to the monitored slew rate exceeding a slew rate threshold; and increasing the pullup current responsive to a voltage level of the signal.
- 10. A method for biasing an open-drain signal line, the method comprising:monitoring a slew rate of a signal on the signal line; providing a pullup current to the signal line responsive to the monitored slew rate exceeding a slew rate threshold, wherein providing the pullup current comprises providing a first current independent of the monitored slew rate, and providing a second current responsive to the monitored slew rate; and increasing the pullup current responsive to a voltage level of the signal.
- 11. The method of claim 10 wherein the second current is provided responsive to the monitored slew rate exceeding a slew rate threshold.
Parent Case Info
This application is a continuation of U.S. patent application Ser. No. 09/116,309, filed on Jul. 15, 1998, and is hereby incorporated by reference herein in its entirety.
US Referenced Citations (7)
Foreign Referenced Citations (1)
Number |
Date |
Country |
37 38 800 |
May 1989 |
DE |
Non-Patent Literature Citations (2)
Entry |
Benchmarq Microelectronics Inc. et al., “System Management Bus Specification,” Smart Battery System Specifications, Revision 1.0, Feb. 15, 1995, pp. 1-17. |
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Continuations (1)
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Number |
Date |
Country |
Parent |
09/116309 |
Jul 1998 |
US |
Child |
10/028243 |
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US |