Daimlerchrysler Corporation

Mark J Stachew

Timothy P Philippart

Mikhail Zarkhin

Vasil Germanski

Robert G Rudzewicz

Dino Bortolin

Daniel B Ciesinski

A switch monitoring system for measuring closure time of a switch in a vehicle when the vehicle ignition switch is off. The switch monitoring system includes an application specific integrated circuit, a low powered stand-by voltage source, and external interface circuitry connected to the switch, The switch monitoring system uses very little current to operate the time base and switches off completely after switch closure has been captured, thus preventing excessive battery drain. The microprocessor software can obtain the time to closure at the next vehicle power-up sequence.

Switch monitoring system

An adjustment circuit and method for reading a measurement output of an automotive oxygen sensor provide correction for outgassing of the sensor and inversion of the measurement output. The adjustment circuit includes a biasing stage connected to a sensor return of the oxygen sensor, where the biasing stage applies a predetermined bias voltage to the sensor return. An input stage is connected to an output of the sensor for retrieving the measurement output from the sensor. The adjustment circuit further includes an A/D conversion system connected to the input stage for adjusting the measurement output based on the bias voltage. The A/D conversion system may further be connected to the biasing stage for retrieving a sensor return output from the sensor. In such cases, a differential module calculates a difference between the sensor return output and the measurement output. The sensor return output defines an actual bias voltage applied to the sensor return.

Method of reading an oxygen sensor input

It is an object of the present invention to provide an assist circuit for a vehicle controller power supply which requires multiple voltage outputs. The assist circuit allows for the supply of a higher voltage which aids the supply of a lower voltage during transient power up. Once both voltages have achieved a specified level, during transient power up, and other power supply components, such as a linear voltage regulator, have stabilized, the assist circuit effectively switches off, allowing the higher voltage to be supplied by a switching power supply and the lower voltage to be supplied by the linear regulator. The assist circuit is most useful in vehicle controllers which have a current foldback feature, by assisting to supply peak current demands before a current foldback can occur during a transient power up stage.

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Fenton, MI, United States of America

Mark J Stachew