US3792316A — Protection device for a power element of an integ…

Claim 1

Independent Claim 355 words

A protection device for a final power element of an integrated circuit responsive to an input signal, wherein the curve of the maximum power dissipatable by said element is given by one branch of a hyperbola whose asymptotes are the coordinate axes and the curve of limitation of the second breakdown zone of said final power element, said curve of limitation being lower than said curve of maximum power, the distance between said two curves increasing with the increase of the voltage present at the output of said element, comprising: a calibrated wire inside said integrated circuit to lead the output current of said final element to an external connecting rheophore; first means for detecting the output voltage value of said final element and the output current value in said calibrated wire for providing a composite input current, said output current value being determined through the measurement of the voltage value across said wire and providing said composite input current with a parametric exponential relationship, between said output voltage and current, the variation of at least one of said parameters giving rise to a family of exponential curves, and one of said parameters being said input current of said first means; and a threshold circuit comprising second means to generate a constant reference current, third means applying said constant reference current to the base of a first transistor, fourth means connecting the emitter/collector path of said first transistor between the input of said integrated circuit and ground, said first transistor responsive to said input current sensed by said first means attaining the value of said constant reference current, to bypass a part of said input signal and to thereby limit the operating point of said final element to a zone delimited by the one of said exponential type curves, among all the curves of said family, which is lower than said maximum power curve and said second breakdown zone limiting curve, said curve of the exponential type being determined, with the other constant parameters, by the value of the parameter corresponding to said input current which is coincident with the value of said reference current.

Claim 2

Dependent Claim 355 words

A protection device for a final power element of an integrated circuit responsive to an input signal, wherein the curve of the maximum power dissipatable by said element is given by one branch of a hyperbola whose asymptotes are the coordinate axes and the curve of limitation of the second breakdown zone of said final power element, said curve of limitation being lower than said curve of maximum power, the distance between said two curves increasing with the increase of the voltage present at the output of said element, comprising: a calibrated wire inside said integrated circuit to lead the output current of said final element to an external connecting rheophore; first means for detecting the output voltage value of said final element and the output current value in said calibrated wire for providing a composite input current, said output current value being determined through the measurement of the voltage value across said wire and providing said composite input current with a parametric exponential relationship, between said output voltage and current, the variation of at least one of said parameters giving rise to a family of exponential curves, and one of said parameters being said input current of said first means; and a threshold circuit comprising second means to generate a constant reference current, third means applying said constant reference current to the base of a first transistor, fourth means connecting the emitter/collector path of said first transistor between the input of said integrated circuit and ground, said first transistor responsive to said input current sensed by said first means attaining the value of said constant reference current, to bypass a part of said input signal and to thereby limit the operating point of said final element to a zone delimited by the one of said exponential type curves, among all the curves of said family, which is lower than said maximum power curve and said second breakdown zone limiting curve, said curve of the exponential type being determined, with the other constant parameters, by the value of the parameter corresponding to said input current which is coincident with the value of said reference current.

Claim 3

Dependent Claim 58 words

Protection device according to claim 1, wherein said first means comprises: a series resistor and diode, parallel connected across said final power element; and a further transistor having its base connected to the connection between said resistor and said diode, its emitter connected to said external rheophore and its collector connected to said base of said first transistor.

Claim 4

Dependent Claim 36 words

Protection device according to claim 1, wherein at least one of said parameters of said exponential relationship is obtained as a high precision ratio between values of components of the same type as said first means.

Claim 5

Dependent Claim 69 words

Protection device according to claim 1, wherein at least one of said exponential parameters is variable as a function of the temperature, the variation of said parameter dependent upon a variation of said exponential curve which corresponds to the value of said constant reference current, thereby compensating the variations in said curve of maximum power and said second breakdown zone limiting curve which occur because of said temperature variation.

Claim 6

Dependent Claim 197 words

A power dissipation protection circuit for a final power element, operable in accordance with a maximum power curve, of an integrated circuit including an input current line and an output current line, comprising first means coupled to said output current line for sensing the current through said final power element and providing a first signal corresponding thereto, second means coupled to said final power element for sensing the voltage across said final power element and providing a second signal corresponding thereto, third means coupled to said first and second means and responsive to said first and second signals to provide a current condition in said third means in accordance with said first and second signals, said current condition representative of an operating point on said power curve of said final power element, a source of reference current, a threshold circuit, said threshold circuit coupled to said input line and to said third means and responsive to said current condition of said third means in excess of said reference current for bypassing a portion of the input current on said input current line, thereby preventing said final power element from exceeding said limitations defined by said power curve.

Claim 7

Dependent Claim 197 words

A power dissipation protection circuit for a final power element, operable in accordance with a maximum power curve, of an integrated circuit including an input current line and an output current line, comprising first means coupled to said output current line for sensing the current through said final power element and providing a first signal corresponding thereto, second means coupled to said final power element for sensing the voltage across said final power element and providing a second signal corresponding thereto, third means coupled to said first and second means and responsive to said first and second signals to provide a current condition in said third means in accordance with said first and second signals, said current condition representative of an operating point on said power curve of said final power element, a source of reference current, a threshold circuit, said threshold circuit coupled to said input line and to said third means and responsive to said current condition of said third means in excess of said reference current for bypassing a portion of the input current on said input current line, thereby preventing said final power element from exceeding said limitations defined by said power curve.

Claim 8

Dependent Claim 88 words

The combination of claim 5 wherein said final power element is a transistor and said third means is a transistor, said third means transistor including a diode coupling its base to the emitter of said final power element transistor, said second means including a resistance coupled between the collector of said final power element transistor and the base of said third means transistor, and said first means includes a resistance coupling the increase in current flow along said output line to the emitter of said third means transistor.

Claim 9

Dependent Claim 45 words

The combination of claim 5 where said threshold circuit includes a transistor having its emitter/collector path coupled between said input current line and a common point, said source of reference current having its current output coupled to the base electrode of said threshold circuit transistor.

Claim 10

Dependent Claim 27 words

The combination of claim 5 wherein said source of reference current varies in accordance with temperature, thereby regulating said final power element in accordance with temperature variation.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1977-02-11	1977-08-13	1978-02-12	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1981-02-11	1981-08-13	1982-02-12	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1985-02-11	1985-08-13	1986-02-12	$7700.00	Window Closed / Lapsed

Protection device for a power element of an integrated circuit

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