US 2026/0074616 A1Published application

Resonant power conversion circuit with asymmetric control to improve conversion efficiency of resonant power conversion circuit at low output voltage

AssigneeRichtek Technology Corporation

InventorsTzu-Chen LIN, Ta-Yung YANG, Kuo-Chi LIU, Yi-Min SHIU

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Abstract

A resonant power conversion circuit for converting an input voltage to an output voltage includes a transformer, a resonant capacitor, a high-side transistor, a low-side transistor, and a control circuit. The transformer includes a primary coil. The resonant capacitor and the primary coil are connected in series to a switch node. The high-side transistor provides the input voltage to the switch node, and the low-side transistor couples the switch node to the ground. In each switch cycle, the control circuit sequentially turns on the high-side transistor, turns on the low-side transistor, turns on the high-side transistor twice, turns on the low-side transistor twice, and turns off both the high-side transistor and the low-side transistor.

Claims24

Dependent claims

A resonant power conversion circuit for converting an input voltage into an output voltage, comprising:

a transformer, comprising a primary coil and a secondary coil, wherein the primary coil is coupled between a switch node and a resonant node;
a resonant capacitor, coupled between the resonant node and a ground;
a high-side transistor, providing the input voltage to the switch node based on a high-side driving signal;
a low-side transistor, coupling the switch node to the ground based on a low-side driving signal;
and
a control circuit, generating the high-side driving signal and the low-side driving signal in each switching period based on a resonant current flowing through the resonant capacitor and the output voltage;
wherein each switching period comprises the following periods:
in a first driving period, the control circuit turns on the high-side transistor and turns off the low-side transistor;
in a second driving period after the first driving period, the control circuit turns off the high-side transistor and turns on the low-side transistor;
in a third driving period after the second driving period, the control circuit turns on the high-side transistor and turns off the low-side transistor;
in a fourth driving period after the third driving period, the control circuit turns off the high-side transistor and turns on the low-side transistor;
and
in a fifth driving period after the fourth driving period, the control circuit turns off both the high-side transistor and the low-side transistor;
wherein in response to the resonant current dropping to zero in the second driving period and a predetermined period having elapsed, the control circuit turns off the low-side transistor.

11 more elements

A resonant power conversion circuit for converting an input voltage to an output voltage, comprising:

a transformer, comprising a primary coil and a secondary coil, wherein the primary coil is coupled between a switch node and a resonant node;
a resonant capacitor, coupled between the resonant node and a ground;
a high-side transistor, providing the input voltage to the switch node based on a high-side driving signal;
a low-side transistor, coupling the switch node to the ground based on a low-side driving signal;
and
a control circuit, generating the high-side driving signal and the low-side driving signal in each switching period based on a resonant current flowing through the resonant capacitor and the output voltage;
wherein each switching period comprises the following periods:
in a first driving period, the control circuit turns off the high-side transistor and turns on the low-side transistor;
in a second driving period after the first driving period, the control circuit turns on the high-side transistor and turns off the low-side transistor;
and
in a third driving period after the second driving period, the control circuit turns off the high-side transistor and turns on the low-side transistor;
wherein a length of the first driving period is a fixed value, so that the high-side transistor is turned on under zero-voltage switching during the second driving period to reduce a frequency for driving the resonant power conversion circuit.

9 more elements

A resonant power conversion circuit for converting an input voltage to an output voltage, comprising:

a transformer, comprising a primary coil and a secondary coil, wherein the primary coil is coupled between a switch node and a resonant node;
a resonant capacitor, coupled between the resonant node and a ground;
a high-side transistor, providing the input voltage to the switch node based on a high-side driving signal;
a low-side transistor, coupling the switch node to the ground based on a low-side driving signal;
and
a control circuit, generating the high-side driving signal and the low-side driving signal in each switching period based on a resonant current flowing through the resonant capacitor and the output voltage;
wherein each switching period comprises the following periods:
in a first driving period, the control circuit turns off the high-side transistor and turns on the low-side transistor;
in a second driving period after the first driving period, the control circuit turns on the high-side transistor and turns off the low-side transistor;
in a third driving period after the second driving period, the control circuit turns off the high-side transistor and turns on the low-side transistor;
in a fourth driving period after the third driving period, the control circuit turns on the high-side transistor and turns off the low-side transistor;
and
in a fifth driving period after the fourth driving period, the control circuit turns off both the high-side transistor and the low-side transistor;
wherein a length of the first driving period is a first fixed value;
wherein the first fixed value is less than one-half of a resonant period;
wherein the resonant period is determined by the resonant capacitor.

13 more elements

Dependencies are inferred from the claim text.

Facts

Application: 19/276,276Filed 22 Jul 2025
Priority: TW 11412382725 Jun 2025
Published: 12 Mar 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H02M 3/01
Conversion of DC power input into DC power output: resonant DC/DC converters
H02M 3/33592
Having at least one active switching element at the secondary side of an isolation transformer: having a synchronous rectifier circuit or a…
H02M 1/0058
Transistor switching losses: by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current…
H02M 3/33571
Having several active switching elements: half-bridge at primary side of an isolation transformer

Family

Application63/691,397Us provisional application · filed 6 Sep 2024
US 2026/0074616 A1This patent

From the US filing history. Foreign family members aren’t listed.

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