Zero Current Detecting Circuit and Method and Related Synchronous Switching Power Converter
First Claim
1. A zero current detecting circuit, comprising:
- a first zero current comparator for determining current variation on an inductor of a synchronous switching power converter so as to output a zero current signal to turn off a down-bridge transistor of the synchronous switching power converter;
a second zero current comparator for determining whether the first zero current comparator turns off the down-bridge transistor too early or too late, and outputting a comparison result;
a counter coupled to the second zero current comparator for ascending or descending a control bit according to the comparison result; and
an adjustable delay unit coupled to the first zero current comparator and the counter for adjusting a delay time according to the control bit, and delaying and outputting the zero current signal according to the delay time, to compensate a negative offset voltage by delay.
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Accused Products
Abstract
A zero current detecting circuit is disclosed. The zero current detecting circuit includes a first zero current comparator for determining current variation on an inductor of a synchronous switching power converter so as to output a zero current signal to turn off a down-bridge transistor of the synchronous power converter; a second zero current comparator for determining whether the first zero current comparator turns off the down-bridge transistor too early or too late and outputting a comparison result; a counter coupled to the second zero current comparator for ascending or descending a control bit according to the comparison result, and an adjustable delay unit coupled to the first zero current comparator and the counter for adjusting a delay time according to the control bit, and delaying and outputting the zero current signal according to the delay time, to compensate a negative offset voltage by delay.
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Citations
13 Claims
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1. A zero current detecting circuit, comprising:
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a first zero current comparator for determining current variation on an inductor of a synchronous switching power converter so as to output a zero current signal to turn off a down-bridge transistor of the synchronous switching power converter; a second zero current comparator for determining whether the first zero current comparator turns off the down-bridge transistor too early or too late, and outputting a comparison result; a counter coupled to the second zero current comparator for ascending or descending a control bit according to the comparison result; and an adjustable delay unit coupled to the first zero current comparator and the counter for adjusting a delay time according to the control bit, and delaying and outputting the zero current signal according to the delay time, to compensate a negative offset voltage by delay. - View Dependent Claims (2, 3, 4, 5)
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6. A synchronous switching power converter with zero current detecting, comprising:
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an up-bridge transistor comprising; a first terminal coupled to an input power supply; a second terminal; and a third terminal for receiving a turned-on signal; a down-bridge transistor comprising; a first terminal coupled to a ground; a second terminal coupled to the second terminal of the up-bridge transistor; and a third terminal for receiving a turned-off signal; an inductor coupled between the second terminal of the down-bridge transistor and an output capacitor; and a zero current detecting circuit comprising; a first zero current comparator for determining current variation on the inductor of a synchronous switching power converter so as to output a zero current signal to turn off a down-bridge transistor of the synchronous switching power converter; a second zero current comparator for determining whether the first zero current comparator turns off the down-bridge transistor too early or too late and outputting a comparison result; a counter coupled to the second zero current comparator for ascending or descending a control bit according to the comparison result; and an adjustable delay unit coupled to the first zero current comparator and the counter for adjusting an delay time according to the control bit, and delaying and outputting the zero current signal according to the delay time, to compensate a negative offset voltage by delay. - View Dependent Claims (7, 8, 9, 10)
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11. A zero current detecting method for a synchronous switching power converter, comprising:
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determining current variation on an inductor of a synchronous switching power converter to output a zero current signal to turn off a down-bridge transistor of the synchronous switching power converter; determining whether the down-bridge transistor is turned off too early or too late and outputting a comparison result; ascending or descending a control bit according to the comparison result; and adjusting a delay time according to the control bit, and delaying and outputting the zero current signal according to the delay time, to compensate a negative offset voltage by delay. - View Dependent Claims (12, 13)
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Specification