Patent ID: 8456217

Claim:
An interface circuit for controlling a cross-domain signal link between a first circuit domain powered by a first voltage source and a second circuit domain powered by a second voltage source in a circuit, comprising: first and second controllers, each of the first and second controllers including a first input coupled to the first voltage source of the first circuit domain and a second input coupled to the second voltage source of the second circuit domain, the first controller being powered by the first voltage source and the second controller being powered by the second voltage source; a first switch controlled by an output of the first controller, the first switch including a first end coupled to the cross-domain signal link and a second end coupled to a first defined voltage state; and a second switch controlled by an output of the second controller, the second switch including a first end coupled to the cross-domain signal link and a second end coupled to a second defined voltage state, wherein, during a power-up of the circuit, if one of the first and second voltage sources is unavailable, at least one of the first and second controllers generates a control signal to engage at least one of the first and second switches and pull the cross-domain signal link to one of the first and second defined voltage states, wherein the first and second controllers include respectively a first exclusive-or and a second exclusive-or.