Motorola Corporation

Isadore Balan

Kirk A Sievers

Field coil current of an alternator is controlled in response to temperature as well as to battery voltage, thus allowing maximum safe output power at any ambient temperature. A monostable circuit is utilized for reducing the maximum duty cycle of the field excitation driver in response to a sensed temperature without increasing power dissipation in the regulator.

Temperature limited voltage regulator circuit

A fault indicating circuit for an automobile alternator battery charging system is disclosed. The charging system comprises an alternator providing a rectified battery charging signal in response to alternator field coil excitation which is controlled by a voltage regulator that senses battery voltage. The fault indicating circuit comprises a low voltage detector circuit which provides constant DC excitation for an indicator lamp in response to low alternator output voltage and a high voltage detector circuit which provides intermittent excitation for the lamp in response to an excessively high alternator output voltage, the lamp being maintained in a de-energized state in response to the normal alternator output voltage.

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Schaumburg, IL, United States of America

Isadore Balan