Patent ID: 6970015
Filing Date: 2005-11-29
Classification: H03K

Abstract:
1. An apparatus for programming the operation of an Input/Output (I/O) circuit connected to a load, comprising: (a) an input buffer for receiving an input signal from the load, wherein an output of the input buffer is coupled to another circuit; (b) an output stage that includes a programmable pre-driver that is coupled to an output driver, the output driver provides an output signal for driving the load and the pre-driver receives a signal from the other circuit that corresponds to the output signal; (c) at least one cell that is included in the programmable pre-driver, wherein each cell includes at least two pull-up transistors and at least two pull-down transistors, and wherein hysteresis is provided in the response of the programmable pre-driver that is related to an imbalance in the sizing ratio of each pull-up transistor and each pull-down transistor in each enabled cell and wherein the hysteresis defines a value for the trip point of the high component of the output signal and another value for the other trip point of the low component of the output signal; and (d) a control circuit that enables the programmable pre-driver to determine a trip point for a high component and another trip point for a low component of the output signal driven by the output driver, wherein the programmable pre-driver enables the operation of the output driver to be adjusted to suit different conditions on the load.