US 5,694,305 A · Method and apparatus for protection of electronic circuitry

Abstract

Protection circuitry incorporates detection circuitry and first and second timer circuits to protect power supply apparatus and associated circuitry from damage due to excessive voltages and/or currents. The detection circuitry initiates the first timer upon detecting potentially damaging voltages and/or currents, caused by, for example, a source or load impedance far different from that for which the power supply apparatus is designed. If the abnormal voltages and/or currents persist for longer than a first period of time, the first timer initiates a second timer that reduces the power output of the power supply apparatus for a second period of time. After expiration of the second period of time, the power supply apparatus returns to normal operation. The cycle described above an repeat indefinitely if necessary to protect against, for example, a sustained short circuit. Incorporation of two timers allows the power supply apparatus to properly power variable loads, such as a motor, that initially draw large current but that do not represent an abnormal load impedance, and to adequately protect the apparatus and associated circuitry from damage.

Claims19

Dependent claims

In electrical power supply apparatus for connection to an electrical input power source and for controlling the power delivered to a load, said apparatus having an oscillator component controlling the power delivered to the load by generating pulses that vary in a first mode of operation in response to at least one feedback signal representative of the power delivered to the load, the improvement comprising

first means for detecting when a first signal representative of the power delivered to the load is outside a known range and for producing a detection output signal indicative thereof and for generating a second electrical signal responsive to the duration of said detection output signal and indicative of said first signal remaining outside said known range for a first period of time, and
second means, in electrical communication with said first means and responsive to said second signal for operating the power supply apparatus in a reduced power output mode for a second period of time.

first means including detection means for detecting when a first signal representative of the power delivered to the load is outside a known range and for producing a detection output signal indicative thereof, said first means further including first timing means, in electrical communication with said detection means and responsive to the duration of said detection output signal, for generating a second electrical signal indicative of said first signal remaining outside said known range for a first period of time, and
second timing means, in electrical communication with said first timing means and responsive to said second signal, for operating the power supply apparatus in a reduced power output mode for a second period of time, and for normally returning, after expiration of said second period of time, said power supply apparatus to the first mode of operation.

In electrical pulse width modulation apparatus for generating pulses to control the power delivered to a load, said pulses varying in a first mode of pulse width modulator operation in response to at least one feedback signal representative of power delivered to a load, the improvement comprising

first means including detection means for detecting when a first signal representative of the power delivered to the load is outside a known range and for producing a detection output signal indicative thereof, said first means further including first timing means, in electrical communication with said detection means and responsive to the duration of said detection output signal, for generating a second electrical signal indicative of said first signal remaining outside said known range for a first period of time, and
second timing means, in electrical communication with said first timing means and responsive to said second signal, for reducing the energy of pulses generated by said pulse width modulation apparatus for a second period of time, and for normally returning, after expiration of said second period of time, said pulse width modulation apparatus to said first mode of operation.

Electrical power control apparatus for connection to an electrical power source and for controlling the power delivered to load, comprising

an oscillator component for generating pulses that vary, in a first mode of power control apparatus operation, in response to at least one feedback signal representative of the power delivered to the load for controlling the power delivered to the load,
a feedback component in electrical communication with said oscillator component for generating said at least one feedback signal in response to the power delivered to the load, said feedback signal representative of the power delivered to the load,
a switching component responsive to said pulses, said switching component in electrical communication with said oscillator component and with an energy storage component, for switching energy from the power source for storage in said energy storage component,
an output conditioning component, in electrical communication with said energy storage component and with the load, for conditioning power drawn from the energy storage component before delivery of the conditioned power to the load,
a detection component in electrical communication with said oscillator component for detecting when a first signal representative of the power output of the oscillator component is outside a known range and for producing a detection output signal indicative thereof,
a first timing component, in electrical communication with said detection component and responsive to the duration of said detection output signal, for generating a second electrical signal indicative of said first signal remaining outside said known range for a first period of time, and
a second timing component, in electrical communication with said first timing means and responsive to said second signal, for operating the power supply apparatus in a reduced power output mode for a second period of time and for normally returning, after expiration of said second period of time, said power supply apparatus to the first mode of operation.

4 more elements

Dependencies are inferred from the claim text.

Method and apparatus for protection of electronic circuitry

Life of this patent

Method and apparatus for protection of electronic circuitry

Life of this patent

Abstract

Claims19