Abstract: An integrated circuit driver for high and low lines in a bus. The driver comprises first and second current sources connected to high and low voltage sources, respectively, and first and second transistor circuits for blocking voltage spikes higher or lower than the voltages provided by the high and low voltage sources. The first current source and the first transistor circuit are series connected between the high voltage supply and the high line, and the second current source and the second transistor circuit are series connected between the low voltage source and the low line.

Abstract: A matched current source bus driver circuit providing time and magnitude matched currents as sources and sinks to a pair of serial bus lines. A reference current path is established in transistors which are structurally mirrored to the devices sourcing and sinking bus line currents. Time regulated switching of the reference current ensures RF suppression while maintaining the match of the source and sink current sources driving the bus. Selective decoupling during a loss of circuit ground condition eliminates spurious injection of current into either bus line.

Abstract: A vehicle odometer system for counting pulses representing translation and storing in nonvolatile form binary data representing the decimal values of the odometer data. The architecture of the circuit is structured to use the data in the more significant digit positions of the odometer count as pointers for the nonvolatile storage addresses used to store data for the less significant digit positions. This arrangement ensures that the endurance capabilities of the nonvolatile memory array are taken into account while apportioning degradation in relation to the significance of the odometer data to be stored. Furthermore, electronic manipulation of the odometer data is prevented by inclusion of a write only high odometer value flag which cannot be removed and is redundantly detected.