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US 11,381,233 B2Granted
Circuit for protecting a power switch
AssigneeSTMicroelectronics (Rousset) SAS
InventorsPhilippe Bienvenu, Antonio Calandra
Life of this patent
Estimating the term…
Abstract
A protection circuit for a transistor switch coupled to a power supply rail operates to modulate a control voltage at a control terminal of the transistor switch. A first circuit detects an overload across the terminals of the switch with respect to a threshold to generate a signal which modulates the control voltage. A second circuit operates to adjust a value of the threshold in response to sensed variations in a supply voltage at the power supply rail.
Claims26
A circuit for protecting a transistor switch coupled to a power supply rail, comprising:
- a first circuit configured to detect an overload across terminals of the transistor switch with respect to a first threshold;
- and
- a second circuit configured to adjust a value of the first threshold according to variations in a supply voltage at the power supply rail from a nominal voltage;
- wherein the second circuit comprises:
- a comparator configured to compare a filtered supply voltage with at least a first level;
- and
- a first validation circuit configured to validate a result of the comparison made by the comparator over at least a first duration of time for a modulation of the value of the first threshold, said first validation circuit comprising a filter circuit configured to filter said supply voltage and generate the filtered supply voltage;
- wherein said first duration of time is longer than a duration of a transient variation in the supply voltage from the nominal voltage.
5 more elements
A circuit for protecting a power transistor coupled to a load, comprising:
- a current sensor configured to sense load current flowing through the power transistor;
- a comparison circuit configured to compare the sensed load current to a threshold;
- a modulation circuit configured to modulate a control voltage at a control terminal of the power transistor in response to an output signal generated by said comparison circuit;
- a threshold control circuit configured to sense a supply voltage provided to said power transistor and change the threshold at the comparison circuit in response to change in the sensed supply voltage from a nominal voltage;
- and
- a filter circuit configured to filter the sensed supply voltage to remove any change in the sensed supply voltage having a time constant that is less than a time constant value of the filter circuit.
3 more elements
A circuit for protecting a power transistor coupled to a load, comprising:
- a voltage sensor configured to sense a supply voltage provided to said power transistor;
- a filter circuit configured to filter the sensed supply voltage to remove any change in the sensed supply voltage having a time constant that is less than a time constant value of the filter circuit;
- comparison circuit configured to compare a filtered sensed supply voltage from the filter circuit to a fixed threshold voltage;
- a set/reset latch circuit that is set in response to the comparison circuit output and reset in response to a delay of the comparison circuit output;
- and
- a modulation circuit configured to modulate a control voltage at a control terminal of the power transistor in response to an output signal generated by said set/reset latch circuit.
3 more elements
A circuit for protecting a transistor switch coupled to a power supply rail, comprising:
- a first circuit configured to detect an overload across terminals of the transistor switch with respect to a first threshold;
- and
- a second circuit configured to adjust a value of the first threshold according to variations in a supply voltage at the power supply rail from a nominal voltage;
- wherein the second circuit comprises:
- a first comparator circuit configured to compare information representative of the supply voltage with at least a first level;
- a first validation circuit configured to validate a result of the comparison made by the first comparator circuit over at least a first duration of time for a modulation of the value of the first threshold;
- and
- a second validation circuit configured to validate the result of the comparison over a second duration of time.
5 more elements
A circuit, comprising:
- a transistor switch coupled in series with a load between a first power rail and a second power rail, wherein the transistor switch is configured to control delivery of current to the load;
- and
- a switch protection circuit having an input coupled to the first power rail and configured to modulate a control signal applied to a control terminal of the transistor switch, wherein the switch protection circuit comprises:
- a detection circuit configured to detect an overload across the transistor switch with respect to a first threshold;
- and
- a threshold control circuit configured to adjust a value of the first threshold as a function of variations in a supply voltage between the first and second power rails, wherein the threshold control circuit is configured to compare information representative of the supply voltage to a second threshold and modify the value of the first threshold if the second threshold is exceeded for a period in excess of a reference period which is longer than a duration of a transient variation in the supply voltage from a nominal voltage.
3 more elements
Dependencies are inferred from the claim text.