Inductor flyback detection using switch gate change characteristic detection
First Claim
1. An apparatus to detect an end of an inductor flyback time interval of a switching power converter, wherein the switching power converter includes an inductor to couple to an input voltage node and a field effect transistor (FET) switch coupled to the inductor, the apparatus comprising:
- a switch gate sensor to couple to a gate of the switch, wherein during operation of the switch gate sensor, the switch gate sensor is configured to;
detect a charge characteristic on a gate of the switch associated with an end of the inductor flyback time interval; and
generate a switch gate sensor signal indicating an end of the inductor flyback time interval.
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Abstract
A method and system monitor gate charge characteristics of one or more field effect transistors in a switching power converter to detect an end of an inductor flyback time interval. The switching power converter includes a switch coupled to an inductor to control current flow in the inductor. When the switch turns OFF, a collapsing magnetic field causes the inductor current to decrease and the inductor voltage to reverse polarity. When the magnetic field completely collapses, the inductor current goes to zero. At the end of the inductor flyback time interval, a voltage is induced across a Miller capacitance of the switch. The voltage can be detected as a transient change in the gate voltage of the switch. A switch gate sensor detects the gate voltage change associated with the end of the inductor flyback time interval and provides a signal indicating an end of the inductor flyback time interval.
165 Citations
23 Claims
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1. An apparatus to detect an end of an inductor flyback time interval of a switching power converter, wherein the switching power converter includes an inductor to couple to an input voltage node and a field effect transistor (FET) switch coupled to the inductor, the apparatus comprising:
a switch gate sensor to couple to a gate of the switch, wherein during operation of the switch gate sensor, the switch gate sensor is configured to; detect a charge characteristic on a gate of the switch associated with an end of the inductor flyback time interval; and generate a switch gate sensor signal indicating an end of the inductor flyback time interval. - View Dependent Claims (2, 3, 4, 5, 6, 7, 21)
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8. A method to detect an end of an inductor flyback time interval of a switching power converter, wherein the switching power converter includes an inductor to couple to an input voltage node and a field effect transistor (FET) switch coupled to the inductor, the method comprising:
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detecting a charge characteristic on a gate of the switch associated with an end of the inductor flyback time interval; and generating a switch gate sensor signal indicating an end of the inductor flyback time interval. - View Dependent Claims (9, 10, 11, 12, 13, 14, 22)
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15. An apparatus to detect an end of an inductor flyback time interval of a switching power converter, wherein the switching power converter includes an inductor to couple to an input voltage node and a field effect transistor (FET) switch coupled to the inductor, the apparatus comprising:
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means for detecting a charge characteristic on a gate of the switch associated with an end of the inductor flyback time interval; and means, coupled to the means for detecting, for generating a switch gate sensor signal indicating an end of the inductor flyback time interval. - View Dependent Claims (16, 17, 18, 19, 20, 23)
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Specification