US 5,293,077 A · Power switching circuit

Abstract

When a current that flows into a power output element is greater than a predetermined value, pulse width-modulated signals are formed which vary in inverse proportion to the current value in order to drive the power output element. When an excess current flows into the power output element, therefore, the power output element is allowed to intermittently operate for only short periods of time, and the current can be decreased during the current-limiting operation.

Claims47

Dependent claims

A semiconductor integrated circuit device formed on a common semiconductor substrate, comprising:

an insulated gate field-effect transistor, having a gate, source and drain, and wherein the semiconductor substrate functions as a drain region;
and a bipolar transistor which is formed on said semiconductor substrate, said bipolar transistor having an emitter, base and collector and wherein the base is connected to the source of said insulated gate field-effect transistor, the emitter is connected to the gate of said insulated gate field-effect transistor, and the collector is connected to the gate or the drain of said insulated gate field effect transistor.

A power switching circuit, comprising:

a power output element coupled to a load element and providing a driving current to said load element;
driver means coupled to the power output element and providing an output signal to drive said power output element in response to an input signal;
and
a circuit for detecting a current flowing into the power output element and controlling operation of the driver means in accordance with a magnitude of the current detected so that an operating period of the power output element will vary in inverse proportion to the magnitude of the detected current when the magnitude of the detected current is greater than predetermined magnitude, including:
a first sense circuit for detecting a first current flowing into the power output element when voltage on an output terminal is lower than a predetermined voltage, said power output element having an output end coupled to the output terminal;
a second sense circuit for detecting a second current flowing into the power output element when the voltage on the output terminal is higher than the predetermined voltage;
a selecting circuit for selecting that one of said first and second currents which has the greater magnitude;
current-voltage converting means for converting the one of said first and second currents selected, in accordance with the magnitude thereof, into a voltage signal;
a saw-tooth wave generator for forming a saw-tooth voltage waveform in response to the input signal;
a comparator circuit for comparing the converted voltage signal with the saw-tooth voltage waveform and for providing an indication signal which indicates that the converted voltage signal is of a voltage magnitude greater than or equal to that of the saw-tooth voltage waveform;
and
a flip-flop which is set by the indication signal and which is reset by each start of the operation of the saw-tooth wave generator, said flip-flop having an output being supplied to an input of said driver means so as to control the operation of the driver means.

9 more elements

A power switching circuit, comprising:

a power output element coupled to a load element and providing a driving current to the load element;
driver means coupled to the power output element and providing an output signal to drive the power output element in response to an input signal;
and
a circuit which includes means for detecting a current flowing into the power output element and means for controlling operation of the driver means in accordance with a magnitude of the current detected by the detecting means so that an operating period of the power output element will vary in inverse proportion to the magnitude of the detected current when the magnitude of the detected current is greater than a predetermined magnitude,
wherein the controlling means includes a flip-flop circuit coupled to the driver means and having first and second logic states, the first logic state thereof occurring when the driving current is being provided to the load element, and the second logic state thereof occurring when a supply of the driving current to the load element is being inhibited,
wherein the load element to be coupled has a resistance characteristic in which the resistance thereof is very small at a moment when the load element is first driven, during start-up of operation of the load element, and that the resistance thereof increases with time as heat is being generated therefrom,
wherein the magnitude of the driving current is inversely responsive to the amount of heat being generated from the load element, the driving current during a normal operating condition of the load element is in the form of intermittent pulse signals during an initial part of the operation of the load element, respectively of progressively decreasing magnitudes and increasing pulse-widths, beginning with an initial driving current pulse signal of a maximum magnitude and minimum pulse-width when the power element is first driven, until a steady-state load element operating condition is effected at which time the drive current remains constant for the duration of the input signal, and
wherein in response to detection of an overcurrent condition at the power output element, of a magnitude substantially greater than the predetermined magnitude, the operating period of the power output element is limited to provide a series of current pulses as the driving current to the load element, for the duration of the input signal, thereby to prevent breakdown of the power output element.

5 more elements

A semiconductor integrated circuit for driving a lamp mounted on a vehicle, comprising:

a power supply terminal to which a power supply voltage is supplied;
an output terminal coupled to the lamp;
an input terminal coupled so as to receive an input signal;
a power MOSFET having a source-drain path coupled between the power supply terminal and the output terminal, said power MOSFET providing via the source-drain path thereof a driving current for turning the lamp on in response to a driving signal corresponding to a voltage level of said power supply voltage plus at least the threshold voltage of said power MOSFET and which is applied to a gate of the power MOSFET;
driver means responsive to the input signal and providing the driving signal to the gate of the power MOSFET to turn the power MOSFET on, the driver means including means for selectively turning the power MOSFET off in response to a control signal;
detecting means coupled to the power MOSFET and providing an output in accordance with a magnitude of the driving current detected;
and
control means for controlling operation of the means for selectively turning the power MOSFET off in response to the output of the detecting means,
wherein the control means includes a bistable circuit coupled to the means for selectively turning the power MOSFET off and providing the control signal when the magnitude of the driving current is greater than a predetermined value so that lighting periods of the lamp become less regular,
wherein the control signal is a pulse width-modulated signal effecting an operating period of the power MOSFET which varies inversely to the magnitude of the detected driving current when the driving current is greater than the predetermined value,
wherein the magnitude of the driving current is inversely responsive to the amount of heat being generated by the lamp, the driving current during a normal operation condition of the lamp is in the form of intermittent pulse signals during an initial part of the operation of the lamp, respectively of progressively decreasing magnitudes and increasing pulse-widths, beginning with an initial driving current pulse signal of a maximum magnitude and minimum pulse-width when the power element is first driven, until a steady-state operating condition of the lamp is effected at which time the driving current remains constant for the duration of the input signal, and
wherein the response to detection of an overcurrent condition at the power MOSFET, of a magnitude substantially greater than the predetermined magnitude, the operating period of the power MOSFET is limited to provide a series of current pulses as the driving current to the lamp, for the duration of the input signal, thereby to prevent breakdown of the power MOSFET.

9 more elements

A method of lighting a lamp, mounted on a vehicle, by a power MOSFET formed in a semiconductor integrated circuit device comprising the steps of:

(a) supplying a control signal to turn on the lamp, the lamp having a resistance characteristic in which the resistance thereof is very small at the moment the lamp is first driven and which increases with time as heat is being generated therefrom;
(b) switching the power MOSFET to an on state in accordance with application of the control signal;
(c) detecting a magnitude of a current flowing through a source-drain path of the power MOSFET which is coupled to the lamp;
(d) comparing the detected magnitude of the current according to step (c) with a predetermined magnitude, which corresponds to an overcurrent condition as that which would cause the power MOSFET to be destroyed;
(e) changing the lighting period of the lamp when the magnitude of the current detected is greater than the predetermined magnitude so that the power MOSFET is switched to an off state in accordance with bringing a bistable circuit into a set state,
wherein a period of time in which the bistable circuit remains in the set state varies in response to the magnitude of the current detected;
(f) after step (e), bringing the bistable circuit into a reset state after a predetermined time is passed, so that the power MOSFET is again turned on;
and
(g) after step (f), repeating steps (c) to (f) if the magnitude of the current detected is greater than the predetermined magnitude,
wherein the magnitude of driving current to the lamp, flowing through the source-drain path of the power MOSFET, is inversely responsive to the amount of heat being generated by the lamp, the driving current during a normal operating condition of the lamp is in the form of intermittent pulse signals during an initial part of the operation of the lamp, respectively of progressively decreasing magnitudes and increasing pulse-widths, beginning with an initial driving current pulse signal of a maximum magnitude and minimum pulse-width when the power MOSFET is first driven, until a steady-state operating condition of the lamp is effected at which time the driving current remains constant for the duration of an operating period of the lamp, and
wherein in response to an overcurrent condition at the power MOSFET, resulting from a short-circuit condition of the lamp, the on state period of the power MOSFET is limited to provide a continuing series of narrow current pulses, at regular intervals, as the driving current to the lamp thereby to prevent breakdown of the power MOSFET.

8 more elements

A power switching circuit, comprising:

a power MOSFET having a source-drain path coupled between a terminal for receiving a power supply potential and a load element and providing a driving current to said load element;
driver means coupled to the power MOSFET and providing an output signal to drive said power MOSFET in response to an input signal;
and
a circuit for detecting a current flowing through the power MOSFET and for controlling operation of the driver means in accordance with a magnitude of the current detected so that an operating period of the power MOSFET will vary in inverse proportion to the magnitude of the detected current when the magnitude of the detected current is greater than a predetermined magnitude, including:
a bistable circuit coupled to the driver means and having first and second logic states, the first logic state thereof occurring when the driving current is being provided to the load element, and the second logic state thereof occurring when a supply of the driving current to the load element is being inhibited;
a first sense circuit for providing a first current indicative of detection of a first current magnitude flowing through the power MOSFET when voltage on an output terminal is lower than a predetermined voltage, the output terminal being effected at the coupling of the power MOSFET to the load element;
a second sense circuit for providing a second current indicative of detection of a second current magnitude through the power MOSFET when the voltage on the output terminal is higher than the predetermined voltage;
a selecting circuit for selecting that one of said first and second currents which has the greater magnitude;
current-voltage converting means for converting the one of said first and second currents selected, in accordance with the magnitude thereof, into a voltage value at each occurrence of an operating period of the power MOSFET;
a saw-tooth wave generator for forming a saw-tooth voltage waveform including a series of saw-tooth waves, each of a time-wise decreasing magnitude, in response to an input signal;
and
a comparator circuit for comparing each converted voltage value with a respective saw-tooth wave and for providing an indication signal indicative of when the saw-tooth wave declines to a voltage value that is equal to or less than the converted voltage value,
wherein the bistable circuit is set to the first state by each start of a saw-tooth wave of the saw-tooth wave generator and is set to the second state by the indication signal, said flip-flop having an output being supplied to an input of said driver means so as to control the operation of the driver means, and
wherein said load element has a resistance characteristic in which the resistance thereof is very small at a moment when the load element is driven and that the resistance thereof increases with time as heat is being generated therefrom.

11 more elements

A power switching circuit, comprising:

a power output element coupled to a load element and providing a driving current to the load element;
driver means coupled to the power output element and providing an output signal to drive the power output element in response to an input signal;
and
a circuit which includes means for detecting a current flowing into the power output element and means for controlling operation of the driver means in accordance with a magnitude of the current detected by the detecting means so that an operating period of the power output element will vary in inverse proportion to the magnitude of the detected current when the magnitude of the detected current is greater than a predetermined magnitude,
wherein the controlling means includes a flip-flop circuit coupled to the driver means and having first and second logic states, the first logic state thereof occurring when the driving current is being provided to the load element, and the second logic state thereof occurring when a supply of the driving current to the load element is being inhibited,
wherein the load element to be coupled has a directly varying resistance-heat characteristic relationship during normal operation thereof in which the resistance thereof is very small at a moment when the load element is first driven and that the resistance thereof increases with time as heat is being generated therefrom,
wherein upon start-up of operation of the power element, in response to said input signal, the driving current is provided as intermittent pulse signals to operate the load element, the pulse signals are provided as long as the magnitude of the detected current is greater than the predetermined magnitude, and
wherein the magnitude of each additional driving current pulse signal, when the load element is operating normally, is progressively decreased and the pulse-width thereof is increased from that of the preceding pulse signal until a steady-state load element operating condition is effected at which time the driving current remains constant for the duration of the input signal, the decrease in magnitude of each additional pulse signal, starting from an initial driving current pulse signal of maximum magnitude and minimum pulse-width, is in response to a corresponding increase in resistance of the load element.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application

07/920,170Filed 27 Jul 1992 · continuation

Priority

JP 63-4719329 Feb 1988

Granted

8 Mar 1994

Term ends

Not estimatedThe source records don’t support an estimate.

Classification10 codes

H02H 9/001
Emergency protective circuit arrangements for limiting excess current or voltage without disconnection: limiting speed of change of electric…
H02M 3/156
Using semiconductor devices only: with automatic control of output voltage or current, e.g. switching regulators
H03K 17/0822
By feedback from the output to the control circuit: in field-effect transistor switches
H05B 39/02
Circuit arrangements or apparatus for operating incandescent light sources: switching on, e.g. with predetermined rate of increase of lighting current

Abstract

Claims47

Dependent claims

A semiconductor integrated circuit device formed on a common semiconductor substrate, comprising:

an insulated gate field-effect transistor, having a gate, source and drain, and wherein the semiconductor substrate functions as a drain region;
and a bipolar transistor which is formed on said semiconductor substrate, said bipolar transistor having an emitter, base and collector and wherein the base is connected to the source of said insulated gate field-effect transistor, the emitter is connected to the gate of said insulated gate field-effect transistor, and the collector is connected to the gate or the drain of said insulated gate field effect transistor.

A power switching circuit, comprising:

a power output element coupled to a load element and providing a driving current to said load element;
driver means coupled to the power output element and providing an output signal to drive said power output element in response to an input signal;
and
a circuit for detecting a current flowing into the power output element and controlling operation of the driver means in accordance with a magnitude of the current detected so that an operating period of the power output element will vary in inverse proportion to the magnitude of the detected current when the magnitude of the detected current is greater than predetermined magnitude, including:
a first sense circuit for detecting a first current flowing into the power output element when voltage on an output terminal is lower than a predetermined voltage, said power output element having an output end coupled to the output terminal;
a second sense circuit for detecting a second current flowing into the power output element when the voltage on the output terminal is higher than the predetermined voltage;
a selecting circuit for selecting that one of said first and second currents which has the greater magnitude;
current-voltage converting means for converting the one of said first and second currents selected, in accordance with the magnitude thereof, into a voltage signal;
a saw-tooth wave generator for forming a saw-tooth voltage waveform in response to the input signal;
a comparator circuit for comparing the converted voltage signal with the saw-tooth voltage waveform and for providing an indication signal which indicates that the converted voltage signal is of a voltage magnitude greater than or equal to that of the saw-tooth voltage waveform;
and
a flip-flop which is set by the indication signal and which is reset by each start of the operation of the saw-tooth wave generator, said flip-flop having an output being supplied to an input of said driver means so as to control the operation of the driver means.

9 more elements

A power switching circuit, comprising:

a power output element coupled to a load element and providing a driving current to the load element;
driver means coupled to the power output element and providing an output signal to drive the power output element in response to an input signal;
and
a circuit which includes means for detecting a current flowing into the power output element and means for controlling operation of the driver means in accordance with a magnitude of the current detected by the detecting means so that an operating period of the power output element will vary in inverse proportion to the magnitude of the detected current when the magnitude of the detected current is greater than a predetermined magnitude,
wherein the controlling means includes a flip-flop circuit coupled to the driver means and having first and second logic states, the first logic state thereof occurring when the driving current is being provided to the load element, and the second logic state thereof occurring when a supply of the driving current to the load element is being inhibited,
wherein the load element to be coupled has a resistance characteristic in which the resistance thereof is very small at a moment when the load element is first driven, during start-up of operation of the load element, and that the resistance thereof increases with time as heat is being generated therefrom,
wherein the magnitude of the driving current is inversely responsive to the amount of heat being generated from the load element, the driving current during a normal operating condition of the load element is in the form of intermittent pulse signals during an initial part of the operation of the load element, respectively of progressively decreasing magnitudes and increasing pulse-widths, beginning with an initial driving current pulse signal of a maximum magnitude and minimum pulse-width when the power element is first driven, until a steady-state load element operating condition is effected at which time the drive current remains constant for the duration of the input signal, and
wherein in response to detection of an overcurrent condition at the power output element, of a magnitude substantially greater than the predetermined magnitude, the operating period of the power output element is limited to provide a series of current pulses as the driving current to the load element, for the duration of the input signal, thereby to prevent breakdown of the power output element.

5 more elements

A semiconductor integrated circuit for driving a lamp mounted on a vehicle, comprising:

a power supply terminal to which a power supply voltage is supplied;
an output terminal coupled to the lamp;
an input terminal coupled so as to receive an input signal;
a power MOSFET having a source-drain path coupled between the power supply terminal and the output terminal, said power MOSFET providing via the source-drain path thereof a driving current for turning the lamp on in response to a driving signal corresponding to a voltage level of said power supply voltage plus at least the threshold voltage of said power MOSFET and which is applied to a gate of the power MOSFET;
driver means responsive to the input signal and providing the driving signal to the gate of the power MOSFET to turn the power MOSFET on, the driver means including means for selectively turning the power MOSFET off in response to a control signal;
detecting means coupled to the power MOSFET and providing an output in accordance with a magnitude of the driving current detected;
and
control means for controlling operation of the means for selectively turning the power MOSFET off in response to the output of the detecting means,
wherein the control means includes a bistable circuit coupled to the means for selectively turning the power MOSFET off and providing the control signal when the magnitude of the driving current is greater than a predetermined value so that lighting periods of the lamp become less regular,
wherein the control signal is a pulse width-modulated signal effecting an operating period of the power MOSFET which varies inversely to the magnitude of the detected driving current when the driving current is greater than the predetermined value,
wherein the magnitude of the driving current is inversely responsive to the amount of heat being generated by the lamp, the driving current during a normal operation condition of the lamp is in the form of intermittent pulse signals during an initial part of the operation of the lamp, respectively of progressively decreasing magnitudes and increasing pulse-widths, beginning with an initial driving current pulse signal of a maximum magnitude and minimum pulse-width when the power element is first driven, until a steady-state operating condition of the lamp is effected at which time the driving current remains constant for the duration of the input signal, and
wherein the response to detection of an overcurrent condition at the power MOSFET, of a magnitude substantially greater than the predetermined magnitude, the operating period of the power MOSFET is limited to provide a series of current pulses as the driving current to the lamp, for the duration of the input signal, thereby to prevent breakdown of the power MOSFET.

9 more elements

A method of lighting a lamp, mounted on a vehicle, by a power MOSFET formed in a semiconductor integrated circuit device comprising the steps of:

(a) supplying a control signal to turn on the lamp, the lamp having a resistance characteristic in which the resistance thereof is very small at the moment the lamp is first driven and which increases with time as heat is being generated therefrom;
(b) switching the power MOSFET to an on state in accordance with application of the control signal;
(c) detecting a magnitude of a current flowing through a source-drain path of the power MOSFET which is coupled to the lamp;
(d) comparing the detected magnitude of the current according to step (c) with a predetermined magnitude, which corresponds to an overcurrent condition as that which would cause the power MOSFET to be destroyed;
(e) changing the lighting period of the lamp when the magnitude of the current detected is greater than the predetermined magnitude so that the power MOSFET is switched to an off state in accordance with bringing a bistable circuit into a set state,
wherein a period of time in which the bistable circuit remains in the set state varies in response to the magnitude of the current detected;
(f) after step (e), bringing the bistable circuit into a reset state after a predetermined time is passed, so that the power MOSFET is again turned on;
and
(g) after step (f), repeating steps (c) to (f) if the magnitude of the current detected is greater than the predetermined magnitude,
wherein the magnitude of driving current to the lamp, flowing through the source-drain path of the power MOSFET, is inversely responsive to the amount of heat being generated by the lamp, the driving current during a normal operating condition of the lamp is in the form of intermittent pulse signals during an initial part of the operation of the lamp, respectively of progressively decreasing magnitudes and increasing pulse-widths, beginning with an initial driving current pulse signal of a maximum magnitude and minimum pulse-width when the power MOSFET is first driven, until a steady-state operating condition of the lamp is effected at which time the driving current remains constant for the duration of an operating period of the lamp, and
wherein in response to an overcurrent condition at the power MOSFET, resulting from a short-circuit condition of the lamp, the on state period of the power MOSFET is limited to provide a continuing series of narrow current pulses, at regular intervals, as the driving current to the lamp thereby to prevent breakdown of the power MOSFET.

8 more elements

A power switching circuit, comprising:

a power MOSFET having a source-drain path coupled between a terminal for receiving a power supply potential and a load element and providing a driving current to said load element;
driver means coupled to the power MOSFET and providing an output signal to drive said power MOSFET in response to an input signal;
and
a circuit for detecting a current flowing through the power MOSFET and for controlling operation of the driver means in accordance with a magnitude of the current detected so that an operating period of the power MOSFET will vary in inverse proportion to the magnitude of the detected current when the magnitude of the detected current is greater than a predetermined magnitude, including:
a bistable circuit coupled to the driver means and having first and second logic states, the first logic state thereof occurring when the driving current is being provided to the load element, and the second logic state thereof occurring when a supply of the driving current to the load element is being inhibited;
a first sense circuit for providing a first current indicative of detection of a first current magnitude flowing through the power MOSFET when voltage on an output terminal is lower than a predetermined voltage, the output terminal being effected at the coupling of the power MOSFET to the load element;
a second sense circuit for providing a second current indicative of detection of a second current magnitude through the power MOSFET when the voltage on the output terminal is higher than the predetermined voltage;
a selecting circuit for selecting that one of said first and second currents which has the greater magnitude;
current-voltage converting means for converting the one of said first and second currents selected, in accordance with the magnitude thereof, into a voltage value at each occurrence of an operating period of the power MOSFET;
a saw-tooth wave generator for forming a saw-tooth voltage waveform including a series of saw-tooth waves, each of a time-wise decreasing magnitude, in response to an input signal;
and
a comparator circuit for comparing each converted voltage value with a respective saw-tooth wave and for providing an indication signal indicative of when the saw-tooth wave declines to a voltage value that is equal to or less than the converted voltage value,
wherein the bistable circuit is set to the first state by each start of a saw-tooth wave of the saw-tooth wave generator and is set to the second state by the indication signal, said flip-flop having an output being supplied to an input of said driver means so as to control the operation of the driver means, and
wherein said load element has a resistance characteristic in which the resistance thereof is very small at a moment when the load element is driven and that the resistance thereof increases with time as heat is being generated therefrom.

11 more elements

A power switching circuit, comprising:

a power output element coupled to a load element and providing a driving current to the load element;
driver means coupled to the power output element and providing an output signal to drive the power output element in response to an input signal;
and
a circuit which includes means for detecting a current flowing into the power output element and means for controlling operation of the driver means in accordance with a magnitude of the current detected by the detecting means so that an operating period of the power output element will vary in inverse proportion to the magnitude of the detected current when the magnitude of the detected current is greater than a predetermined magnitude,
wherein the controlling means includes a flip-flop circuit coupled to the driver means and having first and second logic states, the first logic state thereof occurring when the driving current is being provided to the load element, and the second logic state thereof occurring when a supply of the driving current to the load element is being inhibited,
wherein the load element to be coupled has a directly varying resistance-heat characteristic relationship during normal operation thereof in which the resistance thereof is very small at a moment when the load element is first driven and that the resistance thereof increases with time as heat is being generated therefrom,
wherein upon start-up of operation of the power element, in response to said input signal, the driving current is provided as intermittent pulse signals to operate the load element, the pulse signals are provided as long as the magnitude of the detected current is greater than the predetermined magnitude, and
wherein the magnitude of each additional driving current pulse signal, when the load element is operating normally, is progressively decreased and the pulse-width thereof is increased from that of the preceding pulse signal until a steady-state load element operating condition is effected at which time the driving current remains constant for the duration of the input signal, the decrease in magnitude of each additional pulse signal, starting from an initial driving current pulse signal of maximum magnitude and minimum pulse-width, is in response to a corresponding increase in resistance of the load element.

5 more elements

Dependencies are inferred from the claim text.

Power switching circuit

Life of this patent

Abstract

Claims47

Power switching circuit

Life of this patent

Abstract

Claims47