Motorola Corporation

National Semiconductor Corporation

Karl R Heck

John M Pigott

Robert B Jarrett

A Group III-N high electron mobility transistor is driven by a high-voltage gate driver that limits the gate-to-source voltage across the transistor by controlling the maximum charge that can be placed on a boot strap capacitor that charges up the gate of the transistor to turn on the transistor.

High-voltage gate driver that drives group III-N high electron mobility transistors

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.

Control circuit for an electromechanical device

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.

Reverse battery protection circuit

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.

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Phoenix, AZ, United States of America

Karl R Heck