Constant polarity input device including synchronous bridge rectifier
First Claim
1. A circuit comprising:
- a first and a second input terminal;
a first and a second output terminal;
a bridge rectifier including a plurality of diodes, the bridge rectifier coupled to the first and second input terminals and coupled to the first and second output terminals;
a plurality of transistors, ones of the plurality of transistors coupled in parallel with ones of the plurality of diodes of the bridge rectifier; and
a comparator coupled to the first and second input terminals, the first and second output terminals, and at least one of the plurality of transistors, the comparator operable to provide a control signal to the at least one of the plurality of transistors depending upon a first signal received from the first input terminal and a second signal received from the second input terminal, the control signal operable to activate the at least one of the plurality of transistors when at least one of the ones of the plurality of diodes of the bridge rectifier is forward biased.
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Accused Products
Abstract
A circuit including bridge rectifier, switches across one or more of the diodes of the bridge rectifier, and a comparator providing control signals to the switch or switches can be constructed to apply a constant polarity voltage to an electrical load, regardless of the polarity of the input power applied to the circuit. The comparator produces a control signal depending upon a comparison of the input power voltages, and the control signal activates one or more of the switches to allow current flow through an appropriate path in the circuit to yield the constant polarity across the electrical load. Thus, the circuit can protect the electrical load from an inappropriately applied voltage by switching the applied voltage'"'"'s polarity. Because an activated switch can short a diode in the bridge rectifier, power loss associated with current flow through the diode is reduced. Additionally, the circuit can provide constant polarity across the electrical load with either AC or DC input power.
39 Citations
27 Claims
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1. A circuit comprising:
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a first and a second input terminal;
a first and a second output terminal;
a bridge rectifier including a plurality of diodes, the bridge rectifier coupled to the first and second input terminals and coupled to the first and second output terminals;
a plurality of transistors, ones of the plurality of transistors coupled in parallel with ones of the plurality of diodes of the bridge rectifier; and
a comparator coupled to the first and second input terminals, the first and second output terminals, and at least one of the plurality of transistors, the comparator operable to provide a control signal to the at least one of the plurality of transistors depending upon a first signal received from the first input terminal and a second signal received from the second input terminal, the control signal operable to activate the at least one of the plurality of transistors when at least one of the ones of the plurality of diodes of the bridge rectifier is forward biased. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A computer system comprising:
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a processor;
a memory coupled to the processor; and
a circuit coupled to the processor and memory and operable to deliver power to the processor and memory, the circuit comprising;
a first and a second input terminal;
a first and a second output terminal;
a bridge rectifier including a plurality of diodes, the bridge rectifier coupled to the first and second input terminals and coupled to the first and second output terminals;
a plurality of transistors, ones of the plurality of transistors coupled in parallel with ones of the plurality of diodes of the bridge rectifier; and
a comparator coupled to the first and second input terminals, the first and second output terminals, and at least one of the plurality of transistors, the comparator operable to provide a control signal to the at least one of the plurality of transistors depending upon a first signal received from the first input terminal and a second signal received from the second input terminal, the control signal operable to activate the at least one of the plurality of transistors when at least one of the ones of the plurality of diodes of the bridge rectifier is forward biased. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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21. A method of maintaining a constant power supply polarity across an electrical load, the method comprising:
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comparing a first input voltage with a second input voltage to identify which of the input voltages is more positive than the other;
activating a first pair of switches in a circuit when the first input voltage is more positive than the second input voltage, the switches operable to receive the first and second input voltage so that activating the first pair of switches allows a voltage of a first polarity to develop across the electrical load; and
activating a second pair of switches in a circuit when the second input voltage is more positive than the first input voltage, the switches operable to receive the first and second input voltage so that activating the second pair of switches allows a voltage of the first polarity to develop across the electrical load. - View Dependent Claims (22, 23, 24)
shorting the body diodes of the first pair of switches when the first pair of switches is activated; and
shorting the body diodes of the second pair of switches when the second pair of switches is activated.
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23. The method of claim 21 wherein the first input voltage is a direct current (DC) voltage and the second input voltage is ground.
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24. The method of claim 21 wherein the first input voltage and the second input voltage are derived from an alternating current (AC) power source.
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25. A circuit comprising:
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a first and a second input terminal;
a first and a second output terminal;
a rectifying means coupled to the first and second input terminals and coupled to the first and second output terminals, the rectifying means for maintaining a constant polarity across an electrical load;
a first switching means for shorting a first portion of the rectifying means;
a second switching means for shorting a second portion of the rectifying means; and
a comparing means coupled to the first and second input terminals, the first and second output terminals, and at least one of the first and second switching means, the comparing means for comparing a first voltage on the first input terminal with a second voltage on the second input terminal and providing a control signal to the at least one of the first and second switching means depending upon the comparison, the control signal operable to activate the at least one of the first and second switching means when at least a portion of the rectifying means is forward biased. - View Dependent Claims (26, 27)
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Specification