| 摘要 |
Load-monitoring feedback is used to maintain the slew rate of a line driver circuit at a prescribed rate that is independent of the effective load of the line being driven. This load-monitoring feedback control makes it possible to drive the line with an amplified output signal that faithfully tracks the input signal and conforms with prescribed slew rate and rise/fall time specifications, irrespective of characteristics of the signal line, which may vary over a specified range of component values. In a first embodiment, slew rate control is effected by increasing or decreasing the amount of charge on a reference capacitor and thereby the drive current to an output driver FET, in accordance with the change in state of the output of an output terminal-monitoring voltage threshold comparator relative to termination of a prescribed (one-shot established) time window. In a second embodiment, slew rate control is effected by directly determining the length of time required for the output terminal to transition between first and second states, and adjusting the operation of the output driver FET based on whether the total time measurement is equal to, greater than or less than the slew rate window.
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