Patent Number: 6,166,561

Title: Method and apparatus for protecting off chip driver circuitry employing a split rail power supply

Abstract: OCD circuitry is provided for an integrated circuit having a split rail power supply providing a first and a second voltage. The OCD circuitry comprises a tristate logic circuit adapted to control the OCD and a detection circuit coupled to the tristate logic circuit and adapted to generate an inactivation signal that inactivates the OCD if the first voltage is low. The detection circuit preferably comprises a comparator that compares the first voltage to the second voltage, and that generates the inactivation signal if the first voltage is less than the second voltage. To prevent the inadvertent inactivation of the OCD circuitry, the detection circuit preferably is provided with a filter that sets a minimum time period that the first voltage must be low before the detection circuit generates the inactivation signal and thus inactivates the OCD circuitry.

Inventors: Fifield; John A. (Underhill, VT), Miller; Christopher P. (Underhill, VT)

Assignee: International Business Machines Corporation

International Classification: H03K 19/003 (20060101); H03K 019/00 (); H03L 007/00 ()

Expiration Date: 12/26/2017