High-reliability, low-cost, pulse-width-modulated vehicular alternator voltage regulator with short-circuit protection and low inserted electrical noise

摘要

An output stage of a conventional Frequency-on-Demand electronic voltage regulator, such as a voltage regulator of the type described in U.S. Pat. No. 5,642,033, is reconfigured as a bi-stable multivibrator, or flip-flop. An oscillator provides a reset pulse of pre-defined pulse width and pulse period to initiate an “on” period of the output stage; a conventional error amplifier synchronously switches the output stage “off” when a system voltage reaches a preset value. Voltage regulation by a constant-frequency, pulse-width-modulated, output signal is thus realized at reduced cost and complexity. Total capacitance between the gate-source terminals of a preferred MOS power output transistor serves to slow both negative- and positive-going output control signal transitions, introducing a minimum of electrical noise into the vehicle's electrical system.