Motorola Corporation

David H Overton

Gary L Pace

Silvia M Viteri

A high current driver (100) for driving a high current load (110) in an electronic device powered by a battery (112) comprises a voltage reference (104) for generating a reference voltage, and a drive current controller (102, 302) responsive to a drive control signal for selectively switching the drive current controller (102, 302) from an active state for supplying current to the high current load (110), to an-inactive state for inhibiting the supply of current to the high current load (110). The drive current controller (102, 302) further controls the amount of current supplied to the high current load (110) when the battery (112) terminal voltage is substantially equal to the reference voltage. A load control element (108) is coupled to the drive current controller (102, 302) and drives the high current load (110) when the drive current controller (102, 302) is in the active state.

High current driver providing battery overload protection

A DC-DC converter regulates the maximum current through an inductor. The DC-DC converter operates within a paging receiver and boosts a voltage from a single cell battery to substantially 3.1 VDC in order to operate circuits which require more voltage than that produced by the single cell battery. Such circuits include CMOS microcomputers and code plug. The DC-DC converter is current regulated thus providing for improved power conversion efficiency. The DC-DC converter is active when the voltage is below a minimum voltage and inactive when above a maximum voltage. The DC-DC converter provides for a wide range of load currents from the converted voltage without being controlled by a microcomputer and while delivering the power to the loads with an improved efficiency.

Strobed DC-DC converter with current regulation

A driving circuit including a single transformer drives a piezoelectric transducer and an electroluminescent lamp. The circuit is coupled to the driving circuit for limiting the peak current through the transformer.

Driver circuit for piezoelectric transducer and electroluminescent lamp

An inductively loaded switching transistor circuit for use in the DC-DC converter includes an inductive load and a switching transistor coupled to the inductive load for conducting current flowing therethrough when the switching transistor is on. A drive circuit is provided which is coupled to the switching transistor for supplying a drive current thereto, and feedback means are provided for adjusting the amount of base drive supplied to the switching transistor from the drive circuit. The drive current is varied substantially linearly with respect to the current flowing through the inductive load.

Inductively loaded switching transistor circuit

An improved amplifier with controlled hysteresis and an extremely low current drain capable of operating over a sufficiently large input voltage dynamic range is provided. Two circuits comprising a transistor and a diode are coupled between a differential amplifier and two cross-coupled current mirrors for preventing transistor saturation in the current mirrors.

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Boca Raton, FL, United States of America

David H Overton