Device and method for limiting a current
AssigneeSTMicroelectronics International N.V.
InventorKarl GRANGE
Life of this patent
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Abstract
A device for limiting a current, includes a differential amplifier configured to equalize voltages across a power transistor and a sense transistor and a regulation circuit of an output current of the device for limiting a current. The regulation circuit includes a transconductance amplifier configured to limit the output current when an output electric potential of the differential amplifier is higher than or equal to a reference electric potential proportional to a reference current the value of which is equal to ILIMIT/(N.M), with ILIMIT corresponding to a current limit value, N corresponding to an aspect ratio between the power transistor and the sense transistor, and M corresponding to an aspect ratio between transistors of a current mirror coupled to the sense transistor.
Claims20
A device for limiting a current, including at least one:
- differential amplifier configured to equalize voltages across a power transistor and a sense transistor and including a first input coupled to a first conduction electrode of the power transistor and a second input coupled to a first conduction electrode of the sense transistor;
- and
- regulation circuit of an output current of the device for limiting a current, including at least one transconductance amplifier configured to limit the output current when an output electric potential of the differential amplifier is higher than or equal to a reference electric potential proportional to a reference current having a value equal to ILIMIT/(N.M), with ILIMIT corresponding to a current limit value, N corresponding to an aspect ratio between the power transistor and the sense transistor, and M corresponding to an aspect ratio between transistors of a current mirror coupled to the sense transistor.
A method for limiting a current, comprising at least:
- amplifying a difference between an output current supplied by a power transistor and a sense current supplied by a sense transistor;
- amplifying and converting into a current a difference between a first electric potential having a value proportional to the difference between the output current and the sense current and a reference electric potential proportional to a reference current having a value equal to ILIMIT/(N.M), with ILIMIT corresponding to a current limit value, N corresponding to an aspect ratio between the power transistor and the sense transistor, and M corresponding to an aspect ratio between transistors of a current mirror coupled to the sense transistor;
- limiting the value of the output current when the value of the first electric potential is higher than or equal to that of the reference electric potential.
A device for protecting an interface of an integrated circuit, comprising:
- a power transistor including a gate, a first conduction terminal, and a second conduction terminal configured to provide an output current;
- a sensor transistor including a gate, a first conduction terminal, and a second conduction terminal coupled to the second conduction terminal of the power transistor;
- a differential amplifier including a first input coupled to the first conduction terminal of the power transistor and a second input coupled to the first conduction terminal of the sense transistor;
- a current mirror coupled to the first terminal of the sense transistor;
- and
- a regulator circuit including a transconductance amplifier transconductance amplifier configured to limit the output current when an output electric potential of the differential amplifier is higher than or equal to a reference electric potential proportional to a reference current of the current mirror.
Dependencies are inferred from the claim text.