Robust gauge driving circuit with pulse modulated input
US5698974A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 13, 1995 |
| Grant date | Dec 16, 1997 |
| Priority date | — |
| Expiry date | Feb 13, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R7/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An input circuit for an automotive gauge driver receives a pulse width modulated or pulse frequency signal having a duty cycle representing a parameter to be displayed. A switching transistor controls an RC filter to develop an analog voltage proportional to the parameter. The input circuit biases the transistor to correctly respond to the input signal over a large range of supply voltage and where the ground potential differs from that of the source of the input signal. An output transistor means (or two) in series with a gauge coil (or two) is controlled by the analog voltage to provide coil current to effect linear gauge operation. Diodes in the input circuit limit the analog voltage range to end values which match the turn-on characteristics of the transistor means.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.