Dissipative clamping of an electrical circuit with a clamp voltage varied in response to an input voltage
First Claim
1. An electrical circuit, comprising:
- a dissipative clamp circuit coupled to an input of the electrical circuit;
an inductive element coupled between the dissipative clamp circuit and an output of the electrical circuit; and
a switch coupled in series with the inductive element;
the dissipative clamp circuit coupled to provide a clamp voltage across the inductive element, the clamp voltage provided by the dissipative clamp circuit varied in response to an input voltage received at the input of the electrical circuit, the dissipative clamp circuit coupled to maintain a voltage across the switch below a switch voltage limit.
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Accused Products
Abstract
Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element. The dissipative clamp circuit is coupled to provide a clamp voltage across the inductive element, the clamp voltage is provided by the dissipative clamp circuit responsive to conditions at the input of the electrical circuit, the dissipative clamp circuit is coupled to maintain a voltage across the switch below a switch voltage limit.
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Citations
22 Claims
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1. An electrical circuit, comprising:
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a dissipative clamp circuit coupled to an input of the electrical circuit;
an inductive element coupled between the dissipative clamp circuit and an output of the electrical circuit; and
a switch coupled in series with the inductive element;
the dissipative clamp circuit coupled to provide a clamp voltage across the inductive element, the clamp voltage provided by the dissipative clamp circuit varied in response to an input voltage received at the input of the electrical circuit, the dissipative clamp circuit coupled to maintain a voltage across the switch below a switch voltage limit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method, comprising:
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switching a power supply input on an energy transfer element;
regulating a power supply output by switching the power supply input on the energy transfer element;
clamping a voltage on the energy transfer element to a clamp voltage; and
varying the clamp voltage in response to an input voltage received at the power supply input. - View Dependent Claims (14, 15, 16, 17)
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18. A power supply, comprising:
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an energy transfer element having an energy transfer element input and an energy transfer element output coupled to an output of the power supply;
a switching regulator circuit including a power switch coupled to the energy transfer element input, and a control circuit coupled to the power switch and the output of the power supply, the control circuit coupled to switch the power switch to regulate the output of the power supply; and
a dissipative clamp circuit coupled to the energy transfer element input, the dissipative clamp circuit coupled to a power supply input to receive an input voltage, the dissipative clamp circuit including;
a sensing network coupled to the power supply input to sense the input voltage;
a dissipative element coupled to the sensing network and coupled to the energy transfer element;
an energy storage element coupled to the energy transfer element and the dissipative element; and
a first diode coupled between the power switch and the dissipative element and the energy storage element. - View Dependent Claims (19, 20, 21, 22)
a voltage divider circuit coupled to a reference voltage circuit coupled to the power supply input to provide a scaled voltage responsive to a reference voltage added to the input voltage; and
a second transistor coupled to the dissipative element and coupled to the voltage divider, the second transistor coupled to provide a current that is coupled to decrease linearly with increasing input voltage.
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22. The power supply of claim 21 wherein the reference voltage is provided by the reference voltage circuit coupled to the power supply input, the reference voltage circuit including a zener diode coupled between the voltage divider circuit and the power supply input, the reference voltage circuit further including a second capacitor coupled between the voltage divider circuit and the power supply input.
Specification