Two-wire analog FET-based dimmer switch
First Claim
1. A load control device for controlling the amount of power delivered from an AC power source to an electrical load, the load control device comprising:
- a bidirectional semiconductor switch arranged to be connected in series electrical connection between the AC power source and the electrical load for conducting a load current from the AC power source to the electrical load, the bidirectional semiconductor switch comprising first and second switching transistors coupled in anti-series connection, the first and second switching transistors each operable to be rendered conductive and to remain conductive independent of the magnitude of the load current conducted through the semiconductor switch;
an analog control circuit for generating a timing voltage representative of a desired amount of power to be delivered to the electrical load; and
a drive circuit receiving the timing voltage and rendering the first and second switching transistors conductive and non-conductive each half-cycle in response to the timing voltage, so as to control the amount of power delivered to the electrical load to the desired amount;
wherein the drive circuit controls the first and second switching transistors on a complementary basis.
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Accused Products
Abstract
A two-wire load control device, such as, a dimmer switch, for controlling the amount of power delivered from an AC power source to an electrical load comprise a bidirectional semiconductor switch having first and second anti-series connected switching transistors (such as, for example, field-effect transistors) that are adapted to be coupled between the source and the load, and are controlled to be conductive and non-conductive in a complementary basis. The bidirectional semiconductor switch is operable to be rendered conductive and to remain conductive independent of the magnitude of a load current conducted through semiconductor switch. The dimmer switch also comprises a drive circuit for rendering the first and second switching transistors conductive and non-conductive each half-cycle on the complementary basis, so as to control the amount of power delivered to the electrical load to a desired amount of power.
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Citations
59 Claims
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1. A load control device for controlling the amount of power delivered from an AC power source to an electrical load, the load control device comprising:
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a bidirectional semiconductor switch arranged to be connected in series electrical connection between the AC power source and the electrical load for conducting a load current from the AC power source to the electrical load, the bidirectional semiconductor switch comprising first and second switching transistors coupled in anti-series connection, the first and second switching transistors each operable to be rendered conductive and to remain conductive independent of the magnitude of the load current conducted through the semiconductor switch; an analog control circuit for generating a timing voltage representative of a desired amount of power to be delivered to the electrical load; and a drive circuit receiving the timing voltage and rendering the first and second switching transistors conductive and non-conductive each half-cycle in response to the timing voltage, so as to control the amount of power delivered to the electrical load to the desired amount; wherein the drive circuit controls the first and second switching transistors on a complementary basis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A two-wire load control device for controlling the amount of power delivered from an AC power source to an electrical load, the load control device comprising:
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a bidirectional semiconductor switch arranged to be connected in series electrical connection between the AC power source and the electrical load for conducting a load current from the AC power source to the electrical load, the bidirectional semiconductor switch comprising first and second switching transistors coupled in anti-series connection, the first and second switching transistors each operable to be rendered conductive and to remain conductive independent of the magnitude of the load current conducted through semiconductor switch; an analog control circuit for generating a timing voltage representative of a desired amount of power to be delivered to the electrical load, the analog control circuit coupled so as to conduct a timing current through the electrical load; and a drive circuit for receiving the timing voltage and independently rendering the first and second switching transistors conductive and non-conductive each half-cycle in response to the timing voltage on a complementary basis. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A gate drive circuit for driving first and second anti-series-connected switching transistors in a load control device for controlling the amount of power delivered from an AC power source to an electrical load, the gate drive circuit configured for receipt of a timing voltage representative of a desired amount of power to be delivered to the electrical load, the gate drive circuit coupled to control inputs of the switching transistors for controlling the switching transistors to be conductive and non-conductive in response to the timing voltage, the gate drive circuit comprising:
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a first capacitor coupled to the control input of the first switching transistor for rendering the switching transistor conductive during the positive half-cycles of the AC power source; a second capacitor coupled to the control input of the second switching transistor for rendering the switching transistor conductive during the negative half-cycles of the AC power source; a first pulse transformer having a secondary winding operatively coupled to the first capacitor; a second pulse transformer having a secondary winding operatively coupled to the second capacitor; and a triggering circuit coupled in series with primary windings of the first and second pulse transformers, the triggering circuit operable to conduct a pulse of current through the primary windings of the pulse transformers in response to the timing voltage for charging the first capacitor during the positive half-cycles and the second capacitor during the negative half-cycles, such that the drive circuit is operable to render the first and second switching transistors conductive and non-conductive on a complementary basis each half-cycle for controlling the amount of power delivered to the electrical load to the desired amount. - View Dependent Claims (37, 38)
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39. A gate drive circuit for driving first and second anti-series-connected switching transistors in a load control device for controlling the amount of power delivered from an AC power source to an electrical load, the gate drive circuit configured for receipt of a timing voltage representative of a desired amount of power to be delivered to the electrical load, the gate drive circuit coupled to control inputs of the switching transistors for controlling the switching transistors to be conductive and non-conductive in response to the timing voltage, the gate drive circuit comprising:
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a triggering circuit operable to conduct a pulse of current in response to the timing voltage; a first optocoupler having an input photodiode operable to conduct the pulse of current of the triggering circuit during the positive half-cycles of the AC power source; a second optocoupler having an input photodiode operable to conduct the pulse of current of the triggering circuit during the negative half-cycles; a first SR latch having a set input coupled to an output of the first optocoupler, the first SR latch further comprising an output coupled to the gate of the first switching transistor for rendering the first switching transistor conductive during the positive half-cycles; and a second SR latch having a set input coupled to an output of the second optocoupler, the second SR latch further comprising an output coupled to the gate of the second switching transistor for rendering the second switching transistor conductive during the negative half-cycles; wherein the reset input of the first SR latch is coupled to the set input of the second SR latch, and the reset input of the second SR latch is coupled to the set input of the first SR latch, such that the switching transistors are rendered conductive on a complementary basis.
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40. A load control circuit for coupling in series between an AC source voltage and a load device comprising:
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a controllable bidirectional switch comprising first and second anti-series connected switching transistors for coupling selected portions of positive and negative half-cycles of the AC source voltage to the load device; a timing circuit coupled to the AC source voltage for producing a timing signal; and a gate drive circuit receiving the timing signal and producing separate first and second complementary drive signals for causing the first and second switching transistors of the bidirectional switch to be conductive for the selected portions of the positive and negative half-cycles, respectively, thereby to provide current to the load device from the AC voltage source during the selected portions of the respective positive and negative half-cycles; wherein the gate drive circuit produces the first drive signal during the positive half-cycle and the second drive signal during the negative half-cycle. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59)
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Specification