By a News Reporter-Staff News Editor at Journal of Engineering -- A patent by the inventors Oh, InHwan (Cupertino, CA); Bucheru, Bogdan T. (San Jose, CA), filed on September 25, 2015, was published online on September 26, 2017, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.
Patent number 9774266 is assigned to APPLE INC. (Cupertino, CA).
The following quote was obtained by the news editors from the background information supplied by the inventors: "A power converter is a circuit that performs electrical power conversion between an input port and an output port by, for example, changing an AC input to a DC output or by changing from a DC input at one level to a DC output at another level. It does so while maintaining the output voltage within a given accuracy specification or range, making it easier for downstream components that are powered by the converter output to operate in a predictable fashion. The converter output voltage, however, exhibits a transient change referred to as undershoot, that is below the lower limit of the voltage accuracy specification, typically when the power converter is loaded abruptly. For example, undershoot occurs when a portable consumer electronics device is unplugged from its AC power adapter and is then plugged in. In addition, a power converter can also exhibit overshoot, which is a transient change in the output voltage that is higher than a specified upper accuracy limit. Overshoot typically occurs when the power converter is abruptly unloaded, e.g. when the AC power adapter output plug is removed from the portable device. Undershoot, especially, is a concern because if severe enough then it may essentially create a brownout situation in which the output voltage drops so much that the downstream components that are powered by the converter can no longer function predictably. Conventional techniques to relieve overshoot and/or undershoot of a switch mode power converter, for example, include using smaller phase inductance and larger filter capacitors in the power stage of the converter."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "It has been discovered that conventional solutions for reducing undershoot do not adequately address, in a practical manner, a wide range of circumstances that are encountered by a power converter, including variations in the size of the load, rapid changes in the load, and temperature variations. In particular, this problem occurs with isolated power converters in which there is a feedback path from the converter output node back to an input of a power converter controller. Typically, the feedback path contains a compensation circuit that includes an opto-coupler circuit, which serves to electrically isolate the converter output node from the power input port of the converter.
"In accordance with an embodiment of the invention, a power converter has a controller connected to control a power stage that produces a regulated voltage at a converter output node, using an input signal that is derived through feedback from the output node. A circuit is provided that generates the input signal to the controller, using an opto-coupler circuit whose input node is connected to a compensation circuit. The compensation circuit has a shunt regulator having a) an output that is connected to the input of the opto-coupler circuit through series-connected first and second current limiting elements, and b) an input that is connected to the converter output node. A feedback element that provides feedback to the input of the shunt regulator is connected between the first current limiting element and the second current limiting element. In accordance with another embodiment of the invention, the feedback element that provides feedback to the input of the shunt regulator is connected directly to the output of the shunt regulator. In that embodiment, a diode element connects the output node of the shunt regulator to the converter output node. These embodiments are expected to exhibit reduced undershoot, particularly in a worst-case scenario, for example, when a large load increase occurs during recovery of the output node voltage following an overshoot.
"The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary."
URL and more information on this patent, see: Oh, InHwan; Bucheru, Bogdan T.. Reducing Output Voltage Undershoot in Isolated Power Converters. U.S. Patent Number 9774266, filed September 25, 2015, and published online on September 26, 2017. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=9774266.PN.&OS=PN/9774266RS=PN/9774266
Keywords for this news article include: APPLE INC.
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