Systems and Methods to Auto-Adjust Zero Cross Circuits for Switching Regulators
First Claim
1. An adaptive zero cross circuit comprising:
- a sensor configured to receive a node voltage signal in response to a switching event, the sensor detects a variation in the node voltage signal and, in response, generates a first control signal; and
a zero cross delay module coupled to receive the first control signal and output a second control signal, the second control signal is configurable to reduce a delay time between the switching event and a second event.
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Abstract
Various embodiments of the present invention provide for an adaptive and accurate zero cross circuit that can operate without directly sensing an inductor current. Certain embodiments allow adjustment of a zero crossing condition while eliminating the need for a blanking time. In certain embodiments this is accomplished by detecting the effects of turning off a switch on a switching node voltage of a buck converter.
Some embodiments use a counter to lengthen or shorten the delay time between an inductor crossing a zero value and the effect of the switching event. In one embodiment, the effect of the switching event includes a change in the direction of the switching node voltage from which the direction of a current flowing in the buck converter inductor.
35 Citations
19 Claims
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1. An adaptive zero cross circuit comprising:
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a sensor configured to receive a node voltage signal in response to a switching event, the sensor detects a variation in the node voltage signal and, in response, generates a first control signal; and a zero cross delay module coupled to receive the first control signal and output a second control signal, the second control signal is configurable to reduce a delay time between the switching event and a second event. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A current sensing system comprising:
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a switching network coupled to a switching node having a switching node voltage, the switching network generates a switching event; a storage element coupled between the switching node and an output node, the storage element is configured to deliver power to the output node; a zero cross circuit coupled to the switching network, the zero cross circuit detects a variation in a node voltage signal in response to the switching event and generates a control signal to adjust a delay time between the switching node voltage exceeding a first predetermined threshold value and the switching event; and a control logic coupled to the switching network, the control logic controls the switching network in response to an output voltage and the control signal.
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12. A method to adjust a zero cross condition, the method comprising:
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detecting, in a first cycle, a variation in a node voltage in response to a switching event; based on the variation, determining a time delay between the switching event and a second event; and based on the time delay, reducing, in a second cycle, the time delay by adjusting a switching time of the switching event. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification