Synchronous rectifier circuit
First Claim
1. A control circuit structured to form a synchronous rectifier circuit together with a bridge circuit, wherein the bridge circuit comprises:
- a first transistor arranged between a first input node and a rectification node;
a second transistor arranged between a second input node and the rectification node;
a third transistor arranged between the first input node and a reference node; and
a fourth transistor arranged between the second input node and the reference node,and wherein the control circuit comprises;
a first variable voltage source structured to generate a first threshold voltage which is variable;
a first zero current detection comparator structured to compare a first voltage at the first input node with the first threshold voltage, and to generate a first detection signal having a first level when the first voltage is higher than the first threshold voltage, and having a second level when the first voltage is lower than the first threshold voltage;
a first adjustment comparator structured to compare the first voltage with a first reference voltage;
a first adjustment unit structured to adjust the first threshold voltage generated by the first variable voltage source, based on an output of the first adjustment comparator; and
a control logic structured to switch a state of the bridge circuit according to the first detection signal,and wherein the first adjustment unit comprises an up/down counter structured to select one from among a count up operation and a count down operation, according to an output of the first adjustment comparator,and wherein the first adjustment voltage is set according to a count value of the up/down counter,and wherein the first threshold voltage is variable in the vicinity of zero,wherein the first reference voltage is configured as a negative voltage,wherein the control logic is structured to instruct the bridge circuit to transit from a first state to a second state when the first detection signal becomes the first level,wherein a pair of the first transistor and the fourth transistor are turned off and a pair of the second transistor and the third transistor are turned on in the first state, and the first transistor through the fourth transistor are turned off in second state.
1 Assignment
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Accused Products
Abstract
A first variable voltage source VS1 generates a first threshold voltage VZC1 which is variable. A first zero current detection comparator ZC_CMP1 compares a first voltage VAC1 at a first input node AC1 with the first threshold voltage VZC1, and generates a ZC_DET1 signal which indicates a comparison result. A first adjustment comparator ADJ_CMP1 compares the first voltage VAC1 with a first reference voltage VTH1. A first adjustment unit adjusts the first threshold voltage VZC1 generated by the first variable voltage source VS1, based on the output VF_DET1 of the first adjustment comparator ADJ_CMP1. A control logic switches the state of a bridge circuit according to at least the first detection signal ZC_DET1.
7 Citations
18 Claims
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1. A control circuit structured to form a synchronous rectifier circuit together with a bridge circuit, wherein the bridge circuit comprises:
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a first transistor arranged between a first input node and a rectification node; a second transistor arranged between a second input node and the rectification node; a third transistor arranged between the first input node and a reference node; and a fourth transistor arranged between the second input node and the reference node, and wherein the control circuit comprises; a first variable voltage source structured to generate a first threshold voltage which is variable; a first zero current detection comparator structured to compare a first voltage at the first input node with the first threshold voltage, and to generate a first detection signal having a first level when the first voltage is higher than the first threshold voltage, and having a second level when the first voltage is lower than the first threshold voltage; a first adjustment comparator structured to compare the first voltage with a first reference voltage; a first adjustment unit structured to adjust the first threshold voltage generated by the first variable voltage source, based on an output of the first adjustment comparator; and a control logic structured to switch a state of the bridge circuit according to the first detection signal, and wherein the first adjustment unit comprises an up/down counter structured to select one from among a count up operation and a count down operation, according to an output of the first adjustment comparator, and wherein the first adjustment voltage is set according to a count value of the up/down counter, and wherein the first threshold voltage is variable in the vicinity of zero, wherein the first reference voltage is configured as a negative voltage, wherein the control logic is structured to instruct the bridge circuit to transit from a first state to a second state when the first detection signal becomes the first level, wherein a pair of the first transistor and the fourth transistor are turned off and a pair of the second transistor and the third transistor are turned on in the first state, and the first transistor through the fourth transistor are turned off in second state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A control circuit structured to form a synchronous rectifier circuit together with a bridge circuit, wherein the bridge circuit comprises:
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a first transistor arranged between a first input node and a rectification node; a second transistor arranged between a second input node and the rectification node; a third transistor arranged between the first input node and a reference node; and a fourth transistor arranged between the second input node and the reference node, and wherein the control circuit comprises; a first variable voltage source structured to generate a first threshold voltage which is variable; a first zero current detection comparator structured to compare a first voltage at the first input node with the first threshold voltage, and to generate a first detection signal having a first level when the first voltage is higher than the first threshold voltage, and having a second level when the first voltage is lower than the first threshold voltage; a first adjustment comparator structured to compare the first voltage with a first reference voltage; a first adjustment unit structured to adjust the first threshold voltage generated by the first variable source, based on an output of the first adjustment comparator; and a control logic structured to switch a state of the bridge circuit according to the first detection signal, wherein the first threshold voltage is variable in the vicinity of a rectified voltage at the rectification node, wherein the first reference voltage is configured as a positive voltage that is higher than the rectified voltage, and wherein, when the first detection signal becomes the second level, the control logic instructs the bridge circuit to transit from a third state in which a pair of the second transistor and the third transistor are turned off and a pair of the first transistor and the fourth transistor are turned on, to a fourth state in which the first transistor through the fourth transistor are turned off. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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Specification