Fast acting FET test circuit with current detection for SIR diagnostics
US5872460A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 4, 1996 |
| Grant date | Feb 16, 1999 |
| Priority date | — |
| Expiry date | Oct 4, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/2621
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The firing circuit of an inflatable restraint system is tested to verify operation of two FETs in series with a squib which are used to apply current to the squib. For the test the squib is biased to an intermediate voltage and each FET is turned on alone to apply battery or ground voltage to the squib. High and low voltage detectors sense the voltage excursion past respective thresholds to verify FET operation. A current detector for each FET senses a short when its FET is conducting, and a logic circuit immediately turns off the FET to result in a very brief FET on time. In addition, the voltage detectors may be used to detect shorts prior to FET testing and also to turn off or hold off the FETs when a high or low voltage is detected upon FET testing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.