A method of operating a pull-up circuit includes turning off a first transistor of the pull-up circuit during a failsafe period by a feedback signal, the feedback signal being received by way of a feedback circuit; isolating the first transistor from the feedback circuit during a pull-up period; and coupling or isolating a control terminal of the first transistor and a control terminal of a second transistor of the pull-up circuit during the pull-up period by a first switch.