Patent ID: 6037803
Filing Date: 2000-03-14
Classification: H03K

Abstract:
An integrated circuit with an output buffer having a first mode that provides a totem pole output and a second mode that provides an output for an open drain bus, comprising:a signal to be outputted from the integrated circuit;a mode select signal that selects between the first mode and the second mode;an output terminal coupled to an I/O pad;a pullup transistor coupled between the output terminal and a high voltage;a pulldown transistor coupled between the output terminal and a low voltage, the pulldown transistor including a control input coupled to the signal to be outputted;a mode select circuit coupled between the signal to be outputted and a control input of the pullup transistor, the mode select circuit receiving the mode select signal and being configured to select between a first mode and a second mode, in the first mode, the pullup transistor being activated when the signal to be outputted indicates a high value, in the second mode, the pullup transistor being activated for one clock cycle when the signal to be outputted indicates a high value; anda mode select generation circuit coupled to a specified pin on the integrated circuit, the mode select generation circuit determining the state of the mode select signal based upon how the specific pin is driven during system reset.