Abstract: An integrated circuit which will produce a switched output when the circuit power supply drops a predetermined level below which reliable IC operation is not assured. This reduced power supply condition is referred to as brownout wherein the switching is related to the active devices. A preferred CMOS circuit is disclosed. The switching level is related to the N channel and P channel transistor sum of thresholds which makes the CMOS circuit process adaptive. The circuit is provided with a transistor gate oxide capacitor for improving noise immunity while achieving maximum utilization of IC chip area. In addition, output enable and circuit shutdown capabilities are detailed.
Type:
Grant
Filed:
May 3, 1991
Date of Patent:
February 16, 1993
Assignee:
National Semiconductor Corporation
Inventors:
Christopher M. Hall, Kenneth E. Dubowski