Inverter current load detection and disable circuit
First Claim
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1. A circuit for protecting a voltage inverter, comprising:
- a circuit for sensing a load current of said voltage inverter and for providing a voltage indicative thereof;
a first comparison circuit capable of comparing a first reference voltage to said voltage indicative of said load current of said voltage inverter; and
a disable circuit capable of disabling said voltage inverter when said first comparison circuit signals that said first reference voltage is greater than said voltage indicative of said load current, said disable circuit comprising a second comparison circuit capable of comparing a second reference voltage to a third reference voltage, said second reference voltage applied to said second comparison circuit when said first comparison circuit signals that said first reference voltage is greater than said voltage indicative of said load current, said disable circuit operative in response to said second reference voltage being greater than said third reference voltage.
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Abstract
A circuit and method for protecting a voltage inverter circuit is disclosed. The circuit comprises a first comparison circuit capable of comparing a first reference voltage to a voltage indicative of the load current of the voltage inverter. When the comparison circuit signals that the first reference voltage is greater than the load voltage, a disable circuit coupled to the first comparison circuit disables the voltage inverter. In the preferred embodiment, the inverter provides power to a cold cathode fluorescent lamp which, if damaged, can harm the inverter.
105 Citations
23 Claims
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1. A circuit for protecting a voltage inverter, comprising:
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a circuit for sensing a load current of said voltage inverter and for providing a voltage indicative thereof; a first comparison circuit capable of comparing a first reference voltage to said voltage indicative of said load current of said voltage inverter; and a disable circuit capable of disabling said voltage inverter when said first comparison circuit signals that said first reference voltage is greater than said voltage indicative of said load current, said disable circuit comprising a second comparison circuit capable of comparing a second reference voltage to a third reference voltage, said second reference voltage applied to said second comparison circuit when said first comparison circuit signals that said first reference voltage is greater than said voltage indicative of said load current, said disable circuit operative in response to said second reference voltage being greater than said third reference voltage. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A circuit for protecting a voltage inverter, comprising:
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a circuit for sensing a load current of said voltage inverter and for providing a voltage indicative thereof; first means for comparing a first reference voltage to said voltage indicative of said load current of said voltage inverter; and means for disabling said voltage inverter, said disabling means operative in response to a resolution by said first comparing means that said first reference voltage is greater than said voltage indicative of said load current, said disabling means comprising; second means for comparing a second reference voltage to a third reference voltage; and means for applying said second reference voltage to said second comparing means, said applying means operative in response to said resolution by said first comparing means that said first reference voltage is greater than said voltage indicative of said load current, wherein said disabling means is operative in response to said second reference voltage being greater than said third reference voltage. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for protecting a voltage inverter, said method comprising the steps of:
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sensing the load current of said voltage inverter and providing a voltage indicative of the sensed load current; comparing a reference voltage to the voltage indicative of the load current of said inverter circuit; sending a signal when said first reference voltage is greater than the voltage indicative of said load current; receiving said signal; applying a second reference voltage in response to said received signal; comparing said second reference voltage to a third reference voltage; and sending a disabling signal to said voltage inverter when said second reference voltage is greater than said third reference voltage. - View Dependent Claims (14, 15)
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16. A system for providing power to a lamp, comprising:
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an inverter having an input coupled to a direct current bus and an output for delivering an alternating current; means for producing a voltage, said produced voltage being a function of current passing through said inverter output; first means for comparing said produced voltage with a first reference voltage; and means for decoupling said inverter from said direct current bus when said reference voltage is greater than said produced voltage, wherein said decoupling means comprises; second means for comparing a second reference voltage to a third reference voltage; and means for applying said second reference voltage to said second comparing means, said applying means operative in response to said resolution by said first comparing means that said first reference voltage is greater than said produced voltage, wherein said decoupling means is operative in response to said second reference voltage being greater than said third reference voltage. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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Specification