ZERO-CROSSING DETECTION CIRCUIT AND METHOD FOR SYNCHRONOUS STEP-DOWN CONVERTER
First Claim
1. A zero-crossing detection circuit for a synchronous step-down converter, the zero-crossing detection circuit comprising:
- a) a state determination circuit configured to compare a drain voltage of a synchronous transistor of said synchronous step-down converter against a reference voltage, and to generate a state digital signal indicative of whether a body diode of said synchronous transistor is turned on;
b) a logic circuit configured to convert said state digital signal into a counting instruction signal;
c) a plus-minus counter configured to generate a numerical signal in response to said counting instruction signal;
d) a digital-analog converter configured to generate a correction analog signal based on said numerical signal; and
e) a zero-crossing comparator configured to receive said correction analog signal and said drain voltage of said synchronous transistor, and to provide a zero-crossing comparison signal to a driving circuit of said synchronous step-down converter.
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Accused Products
Abstract
In one embodiment, a zero-crossing detection circuit for a synchronous step-down converter, can include: (i) a state determination circuit configured to compare a drain voltage of a synchronous transistor of the synchronous step-down converter against a reference voltage, and to generate a state digital signal indicative of whether a body diode of the synchronous transistor is turned on; (ii) a logic circuit configured to convert the state digital signal into a counting instruction signal; (iii) a plus-minus counter configured to generate a numerical signal in response to the counting instruction signal; (iv) a DAC configured to generate a correction analog signal based on the numerical signal; and (v) a zero-crossing comparator configured to receive the correction analog signal and the drain voltage of the synchronous transistor, and to provide a zero-crossing comparison signal to a driving circuit of the synchronous step-down converter.
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Citations
10 Claims
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1. A zero-crossing detection circuit for a synchronous step-down converter, the zero-crossing detection circuit comprising:
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a) a state determination circuit configured to compare a drain voltage of a synchronous transistor of said synchronous step-down converter against a reference voltage, and to generate a state digital signal indicative of whether a body diode of said synchronous transistor is turned on; b) a logic circuit configured to convert said state digital signal into a counting instruction signal; c) a plus-minus counter configured to generate a numerical signal in response to said counting instruction signal; d) a digital-analog converter configured to generate a correction analog signal based on said numerical signal; and e) a zero-crossing comparator configured to receive said correction analog signal and said drain voltage of said synchronous transistor, and to provide a zero-crossing comparison signal to a driving circuit of said synchronous step-down converter. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A zero-crossing detection method for a synchronous step-down converter, the method comprising:
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a) providing an initial value of a plus-minus counter to a digital-analog converter, and generating a correction analog signal via digital-analog conversion; b) triggering a zero-crossing comparator at an initial threshold point, turning off a synchronous transistor, comparing a reference voltage against a drain voltage of said synchronous transistor to determine a comparison result, and determining whether a body diode of said synchronous transistor is turned on according to said comparison result; c) converting, by a logic circuit, a state digital signal indicative of whether said body diode of said synchronous transistor is turned on to a counting instruction signal; d) executing, by said plus-minus counter, said counting instruction signal, and generating a numerical signal indicative of an offset correction amount; e) converting, by said digital-analog converter, said numerical signal to a correction analog signal indicative of an actual offset correction amount; and f) providing said correction analog signal and said drain voltage of said synchronous transistor to said zero-crossing comparator, and a zero-crossing comparison signal to a driving circuit of said synchronous step-down converter for turning off said synchronous transistor. - View Dependent Claims (9, 10)
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Specification