Method of preventing inversion of output current flow in a voltage regulator and related voltage regulator

摘要

The reversal of the flow of output current in a voltage regulator is prevented by equipping the voltage regulator of a regulation transistor controlled by an analog voltage control, having its current terminals connected between the control terminal of the fifth transistor power of the regulator and the power supply line or the common ground node of the regulator. The regulation transistor is configured to provide an electrical path of conduction between the control terminal and the power supply line or the ground node and is controlled by an analog voltage control that varies in a continuous manner between a first level, suitable to extinguish the regulation transistor, and a second level suitable for biasing it in an operating condition of deep conduction, as the difference between the supply voltage and the regulated output voltage approaching an offset voltage.

主权项

1. A voltage regulator configured to generate an output regulated voltage on an output terminal, comprising:
a power transistor configured to be controlled with an error voltage representing a difference between said output regulated voltage and a nominal level of said output regulated voltage, the power transistor being in an output current electric path from a supply line of the regulator to said output terminal; and a protection circuit configured to protect the voltage regulator from inversion of current flow throughout said output current electric path, wherein said protection circuit comprises:
a regulation transistor having current terminals electrically coupled between a control terminal of the power transistor and either said supply line or a common ground node of the voltage regulator, the regulation transistor being configured to constitute a conduction electric path from said control terminal to either said supply line or said common ground node; andan auxiliary operational amplifier configured to generate in operation, and supply to a control terminal of the regulation transistor, an analog control voltage that varies in a continuous manner from a first level, suitable for keeping off said regulation transistor, to a second level, suitable for biasing said regulation transistor in a deep conduction functioning condition, until a difference between a supply voltage and the output regulated voltage approaches a first offset voltage.