Patent ID: 6028450
Filing Date: 2000-02-22
Classification: H03K

Abstract:
A programmable input/output (I/O) circuit for transmitting output signals on or receiving input signals from an I/O terminal, the I/O circuit comprising:a pull-up transistor connected between a system voltage source and the I/O terminal, the pull-up transistor having a gate and a bulk terminal;a gate bias control circuit connected between the system voltage source and the I/O terminal, the gate bias control circuit having an output terminal connected to the gate of the pull-up transistor and an input terminal for receiving a mode control signal;a well bias control circuit connected to the system voltage source, the well bias control circuit having an output terminal connected to the bulk terminal of the pull-up transistor and an input terminal for receiving the mode control signal,wherein the gate bias control circuit connects the gate of the pull-up transistor to the I/O terminal and the well bias control circuit connects the bulk terminal of the pull-up transistor to the I/O terminal when the mode control signal indicates a first operating mode, andwherein the gate bias control circuit connects the gate of the pull-up transistor to the system voltage source and the well bias control circuit connects the bulk terminal of the pull-up transistor to the system voltage source when the mode control signal indicates a second operating mode.