1. An integrated circuit output driver circuit comprising: a push-pull output circuit comprising a pullup output transistor having a drain connected to a data communication line, and a pulldown output transistor having a drain connected to the data communication line; a first adjustable circuit connected to a source of the pullup output transistor for adjusting a resistance between the source of the pullup output transistor and a first reference voltage; and a second adjustable circuit connected to a source of the pulldown output transistor for adjusting a resistance between the source of the pulldown output transistor and a second reference voltage.