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US 7,609,494 B2Granted
Voltage protection system and method for a powered device
AssigneeSilicon Laboratories Inc.
InventorRichard Bruce Webb
Life of this patent
Estimating the term…
Abstract
A powered device includes a voltage protection circuit, two outputs, a switch, and a snubber circuit. The two outputs of the integrated circuit may be coupled to an external transformer. The snubber circuit of the integrated circuit is responsive to the switch and is coupled with respect to the two outputs to direct energy from at least one of the two outputs to the voltage protection circuit.
Claims26
A powered device comprising:
- a voltage protection circuit of an integrated circuit;
- two pins of the integrated circuit coupleable to an external transformer;
- a switch of the integrated circuit, the switch comprising a transistor having a first terminal coupled to a terminal of an external transformer, a control terminal responsive to Power over Ethernet (PoE) protocol logic, and a second terminal coupled to the negative supply terminal, the switch to selectively couple the first and second terminals to activate the external transformer;
- and
- a snubber circuit of the integrated circuit responsive to the switch, the snubber circuit responsive to the two pins to direct energy resulting from a power event away from the switch to the voltage protection circuit.
2 more elements
A method comprising:
- detecting a power event at a snubber circuit of an integrated circuit, the snubber circuit responsive to first and second pins coupled to an external transformer, the external transformer coupled to a negative supply terminal of the integrated circuit;
- directing energy resulting from the power event to a voltage protection circuit via the snubber circuit when a voltage level of the power event exceeds a threshold, the threshold being less than a safe power level of a switch within the integrated circuit;
- wherein the voltage protection circuit is adapted to shunt a current between a first power supply terminal and a second power supply terminal and to clamp a voltage between the first and second power supply terminals to a level that is below a voltage rating associated with the switch.
An integrated circuit comprising:
- a transistor including a first terminal, a second terminal coupled to a first power supply terminal, and a control terminal;
- a pin coupled to the first terminal of the transistor and responsive to an external transformer;
- and
- a snubber circuit responsive to the pin to direct an inductive voltage that exceeds a threshold to a voltage protection circuit to protect the transistor, the snubber circuit comprising:
- a first diode circuit including an anode terminal coupled to a second power supply terminal of the pair of power supply terminals and including a cathode terminal;
- and
- a second diode circuit including an anode terminal coupled to the interface and a cathode terminal coupled to the cathode terminal of the first diode circuit:
- wherein the first diode circuit blocks current flow when a voltage level across the snubber circuit is less than the threshold.
5 more elements
A powered device comprising:
- first and second input pins responsive to an external power source;
- first and second output pins responsive to an external transformer, the first output pin coupled to the first input pin;
- an output switch responsive to a logic circuit;
- a third output pin coupled to the second input pin via the output switch;
- a voltage protection circuit to limit an input voltage to a level that is less than an over-voltage threshold;
- and
- a snubber circuit responsive to the second pin and adapted to direct an inductive voltage that exceeds an output threshold to a voltage protection circuit to protect the output switch;
- wherein, when a voltage across the first and second input pins is below below the over-voltage threshold and an output voltage across the first and second output pins exceeds the output threshold, power applied to the second output pin is directed to the voltage protection circuit;
- wherein, when a voltage on the first and second input pins is at a voltage level that between the over-voltage threshold and an input threshold, power applied to the second output pin is directed to the third output pin via the output switch.
6 more elements
Dependencies are inferred from the claim text.