Power-up detector circuit
US5828251A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 2, 1996 |
| Grant date | Oct 27, 1998 |
| Priority date | — |
| Expiry date | Jul 2, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/223
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An integrated circuit includes a power-up detector circuit that includes a node that is held at a charged state by a capacitor during normal operation. The voltage on the node is sensed by a sensing circuit, typically an inverter that produces a power-up reset pulse when power is initially applied. However, the voltage on the node may not properly discharge in all cases during brief power interruptions. Therefore, to increase the reliability of the power-up detector, a discharge circuit is included to help ensure that the voltage sensed by the power supply voltage-sensing circuit is at the proper level when the power supply voltage drops below a given level. The discharge circuit comprises a first capacitor that turns on a node discharge transistor when the power supply voltage drops below the given level. To provide protection against false discharge, a second capacitor is optionally provided that prevents the discharge transistor from conducting during very brief power supply voltage interruptions. In a preferred embodiment, the second capacitor is effectively disabled at low power supply voltages. This facilitates conduction of the discharge transistor for power supply voltage i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.