Christie, Parker & Hale, LLP
SCSI controller having output driver with slew rate control
 An integrated circuit provides for adjustable slew rate control for both rising and falling edges of an output provided to an SCSI bus. Slew rate is controlled by adaptively varying the charge and/or discharge rate of the gate electrode of an output driver's N-channel pull-down transistor. Charge time and, thus, the falling edge slew rate, is adaptively varied by selectively adding the current source P-channel transistors to a current bus coupled to the gate electrode of the pull-down transistor. Similarly, the discharge rate and, thus, the rising edge slew rate, is adaptively adjusted by selectively switching current sink transistors on to the current bus coupled to the pull-down transistor's gate electrode. The amount of currents sourced or sunk is determined by varying the W/L ratios of both the current source and current sink transistors. 
Adaptec, Inc.
H G
H03K G06F
inventional inventional
Thomas R. Takashi
Schneider Asami