| 摘要 |
Disclosed are output drivers for integrated circuit chips which receive a second supply voltage VCCQ for driving signals off the chips. The output drivers according to the present invention can accept a wide range of voltage values for the second supply voltage VCCQ, and control their rise and fall slew times so that there is only a small variation in the slew times over a wide range of VCCQ values. The charging and discharging of the driver's pull-up and pull-down transistors is varied as a function of the second supply voltage VCCQ. In one set of embodiments, constructive discharge current branches and charging current branches are selectively activated depending upon the value of VCCQ. In other embodiments, counteracting discharge current branches and charging current branches are selectively activated depending upon the value of VCCQ. Drivers according to the present invention enable integrated circuits to be used with a wide variation of second supply voltages VCCQ while maintaining consistent slew times and low noise levels.
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