Over-voltage protection circuit
AssigneeFairchild Semiconductor Corporation
InventorsJames Holt, John So
Life of this patent
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Abstract
In an embodiment of the invention a circuit is used for providing a regulated voltage. The circuit comprises an upper transistor connected to an input voltage from a voltage source, a lower transistor connected to the upper transistor, a pulse width modulator for generating control signals for the upper and lower transistors and a voltage protection circuit. The voltage protection circuit comprises an over-voltage detector circuit powered by the regulated voltage. The voltage protection circuit can cause the lower transistor to draw sufficient current from the voltage source such that an over-voltage condition becomes abated.
Claims15
A circuit for providing a regulated voltage comprising:
- an upper transistor connected to an input voltage from a voltage source, the upper transistor having a control terminal;
- a lower transistor connected to the upper transistor, the lower transistor having a control terminal;
- a voltage regulator connected to receive the regulated voltage, the voltage regulator operable to generate a first control signal applied to the control terminal of the upper transistor, and further operable to generate a second control signal applied to the control terminal of the lower transistor;
- and
- a voltage protection circuit comprising:
- an over-voltage detector circuit powered by the regulated voltage operable to detect an over-voltage condition and further operable to generate an over-voltage detected signal, wherein the over-voltage detected signal causes the lower transistor to draw sufficient current from the voltage source such that the over-voltage condition is abated.
A circuit for protecting against over-voltage comprising:
- an over-voltage detector powered by a regulated voltage operable to generate an over-voltage detected signal;
- an amplifier powered by the regulated voltage operable to generate a trigger signal in response to the over-voltage detected signal;
- and
- a thyristor adapted to clamp the regulated voltage in response to the trigger signal.
A method for providing a regulated voltage comprising:
- providing an upper transistor connected to an input voltage from a voltage source, the upper transistor having a control terminal;
- providing a lower transistor connected to the upper transistor, the lower transistor having a control terminal;
- providing a voltage regulator connected to receive the regulated voltage, the voltage regulator operable to generate a first control signal applied to the control terminal of the upper transistor, and further operable to generate a second control signal applied to the control terminal of the lower transistor;
- and
- providing a voltage protection circuit comprising:
- an over-voltage detector circuit powered by the regulated voltage operable to detect an over-voltage condition and further operable to generate an over-voltage detected signal, wherein the over-voltage detected signal causes the lower transistor to draw sufficient current from the voltage source such that the over-voltage condition is abated.
A method for protecting against over-voltage conditions comprising:
- providing an over-voltage detector powered by a regulated voltage operable to generate an over-voltage detected signal;
- providing an amplifier powered by the regulated voltage operable to generate a trigger signal in response to the over-voltage detected signal;
- and
- providing a thyristor operable to clamp the regulated voltage in response to the trigger signal.
Dependencies are inferred from the claim text.