Abstract: A circuit for controlling current flow (I.sub.COIL) through a coil of an electromechanical device (101) uses a first timer (118) to measure the pulse width of a first drive pulse (22) and to store a proportional first value at an output (121). A second timer (124) receives the first value and generates a second value less than the first value to represent a time interval shorter than the pulse width of the first drive pulse. The second timer initiates the time interval with a second drive pulse (24) and provides a sampling signal (V.sub.SAMPLE) as the time interval terminates to sense an average current flow through the coil before the second drive pulse terminates.

Abstract: A protection circuit (10) for protecting internal circuitry of an integrated circuit (26) from a reverse battery connection has been provided. The protection circuit includes a pass transistor (14) which is rendered operative when the supply voltage is properly connected to the integrated circuit. However, when the power supply is improperly connected, a second transistor (32) becomes active thereby rendering the pass transistor inactive and not allowing the reverse supply voltage to be applied to the internal circuitry.

Abstract: A comparator circuit is provided compatible with CMOS logic levels for the input signal and including a substantially zero standby current when the input signal is initially less than the upper trip threshold. The trip threshold follows a bandgap voltage with a zero temperature coefficient, while hysterisis is provided with the upper and lower trip thresholds. An alternate embodiment of the comparator circuit provides a selectable zero temperature coefficient for the trip threshold as a ratio of emitter resistors while maintaining the hysterisis with the upper and lower trip thresholds.

Abstract: An electrical power driver system with fault monitoring provision for both a self test mode and a normal operating mode. During the self test mode, the power driver is momentarily actuated during test intervals and its output compared to a predetermined value for providing self test fault indications. Each power driver is sampled and an indication provided of whether the fault is new or old in addition to providing a count of faults. During normal operation, monitoring circuitry provides indications of a plurality of fault types including over temperature, open circuit, short to ground, and short to voltage. A determination is made of whether each fault type is new or old and a count of faults provided. Output formatting provides indications of fault type, fault count, and whether the fault is intermittent or hard.