Patent ID: 7304514
Filing Date: 2007-12-04
Classification: H03K

Abstract:
1. A circuit for sensing voltage on an internal node in an integrated circuit including: a first I/O pad on the integrated circuit; a second I/O pad on the integrated circuit; a voltage-sensor power node; a voltage-sensor circuit having an input coupled to the internal node and having a power connection coupled to the voltage-sensor power node, the voltage-sensor circuit also having an output; a power-supplying circuit coupled to the first I/O pad and to the voltage sensor power node, the power-supplying circuit configured to place a voltage-sensor power supply potential on the voltage sensor power node when a voltage larger than a threshold value is present on the first I/O pad; and a first switch coupled between the output of the voltage-sensor circuit and the second I/O pad, the first switch having a control element coupled to the voltage-sensor power node and configured to turn on the first switch when the voltage-sensor power supply potential is present on the voltage sensor power node.