# US 12,603,576 B2 · Switching power converter controller for digital control of constant-power mode > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,603,576 B2 - Document ID: US12603576B2 - Status: Granted - Kind: B2 - Application number: 18/331,078 - Filed: 2023-06-07 - Published: 2024-12-12 - Granted: 2026-04-14 - Earliest claimed: 2023-06-07 - Assignees: Renesas Design North America Inc. - Applicants: Renesas Design North America Inc. - Inventors: Tao Li; Yimin Chen; Juyoung Yoon - Web page: https://patentgrep.com/patent/US12603576B2 ## CPC - H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)} - H02M 3/33523: {with galvanic isolation between input and output of both the power stage and the feedback loop} - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) ## Abstract A switching power converter is provided with digital control of a constant-power mode. During the constant-power mode, the switching power converter may approximate an analog constant-power mode by incrementing or decrementing the output voltage by discrete voltage steps. At each discrete voltage step, the output current may vary within a range while the output voltage is kept constant. Alternatively, the switching power converter may approximate an analog constant-power mode by incrementing or decrementing the output current by discrete current steps. At each discrete current step, the output voltage may vary within a range while the output current is kept constant. ## Claims ### Claim 1 A switching power converter, comprising: a transformer having a primary winding and a secondary winding, wherein the secondary winding is coupled to an output node for an output voltage; a power switch in series with the primary winding; and a controller configured to: control a cycling of the power switch to regulate the output voltage to equal a maximum voltage during a constant-voltage mode; transition from the constant-voltage mode to a constant-power mode in response to an output current of the switching power converter being greater than a maximum current of the constant-voltage mode; control the cycling of the power switch to regulate the output voltage to equal a first constant voltage while the output current of the switching power converter is within a first current range, wherein the first constant voltage is less than the maximum voltage by a discrete voltage step, and calculate a first constant-power reference current by a division of a constant power of the constant-power mode by the first constant voltage, wherein the first current range includes the first constant-power reference current. ### Claim 2 (depends on 1) The switching power converter of claim 1, wherein the controller is a secondary-side controller coupled to the output node. ### Claim 3 (depends on 1) The switching power converter of claim 1, wherein the controller is a primary-side controller coupled to the power switch. ### Claim 4 (depends on 1) The switching power converter of claim 1, wherein the controller is further configured to: decrement the first constant voltage by the discrete voltage step responsive to the output current of the switching power converter being greater than a maximum current of the first current range to provide a second constant voltage; determine a second constant-power reference current by a division of the constant power by the second constant voltage; and control the cycling of the power switch to regulate the output voltage to equal the second constant voltage while the output current of the switching power converter is within a second current range including the second constant-power reference current. ### Claim 5 (depends on 4) The switching power converter of claim 4, wherein the controller is further configured to: decrement the second constant voltage by the discrete voltage step responsive to the output current of the switching power converter being greater than a maximum current of the second current range to provide a third constant voltage; determine a third constant-power reference current by a division of the constant power by the third constant voltage; and control the cycling of the power switch to regulate the output voltage to equal the third constant voltage while the output current of the switching power converter is within a third current range including the third constant-power reference current. ### Claim 6 (depends on 4) The switching power converter of claim 4, wherein the controller is further configured to: increment the second constant voltage by the discrete voltage step responsive to the output current of the switching power converter being less than a minimum current of the second current range to provide a third constant voltage; determine a third constant-power reference current by a division of the constant power by the third constant voltage; and control the cycling of the power switch to regulate the output voltage to equal the third constant voltage while the output current of the switching power converter is within a third current range including the third constant-power reference current. ### Claim 7 (depends on 1) The switching power converter of claim 1, wherein the controller is further configured to: transition to a constant-current mode in response to the output current of the switching power converter exceeding a reference current of the constant-current mode; and control the cycling of the power switch to regulate the output current of the switching power converter to equal the reference current of the constant-current mode during the constant-current mode. ### Claim 8 A switching power converter, comprising: a transformer having a primary winding and a secondary winding, wherein the secondary winding is coupled to an output node for an output voltage; a power switch in series with the primary winding; a controller configured to control a cycling of the power switch so that an output current of the switching power converter equals a constant current during a constant-current mode; transition from the constant-current mode to a constant-power mode in response to the output voltage being greater than a maximum voltage of the constant-current mode; control the cycling of the power switch to regulate the output voltage to equal a first constant voltage while an output current of the switching power converter is within a first current range, wherein the first constant voltage is greater than the maximum voltage by a discrete voltage step, and calculate a first constant-power reference current by a division of a constant power of the constant-power mode by the first constant voltage, wherein the first current range includes the first constant-power reference current. ### Claim 9 (depends on 8) The switching power converter of claim 8, wherein the controller is a secondary-side controller coupled to the output node. ### Claim 10 (depends on 8) The switching power converter of claim 8, wherein the controller is a primary-side controller coupled to the power switch. ### Claim 11 (depends on 8) The switching power converter of claim 8, wherein the controller is further configured to: increment the first constant voltage by the discrete voltage step responsive to the output current of the switching power converter being less than a minimum current of the first current range to provide a second constant voltage; determine a second constant-power reference current by a division of the constant power by the second constant voltage; and control the cycling of the power switch to regulate the output voltage to equal the second constant voltage while the output current of the switching power converter is within a second current range including the second constant-power reference current. ### Claim 12 (depends on 11) The switching power converter of claim 11, wherein the controller is further configured to: increment the second constant voltage by the discrete voltage step responsive to the output current of the switching power converter being less than a minimum current of the second current range to provide a third constant voltage; determine a third constant-power reference current by a division of the constant power by the third constant voltage; and control the cycling of the power switch to regulate the output voltage to equal the third constant voltage while the output current of the switching power converter is within a third current range including the third constant-power reference current. ### Claim 13 (depends on 11) The switching power converter of claim 11, wherein the controller is further configured to: decrement the second constant voltage by the discrete voltage step responsive to the output current of the switching power converter being greater than a maximum current of the second current range to provide a third constant voltage; determine a third constant-power reference current by a division of the constant power by the third constant voltage; and control the cycling of the power switch to regulate the output voltage to equal the third constant voltage while the output current of the switching power converter is within a third current range including the third constant-power reference current. ### Claim 14 (depends on 8) The switching power converter of claim 8, wherein the controller is further configured to: transition to a constant-voltage mode in response to the output voltage exceeding a reference voltage of the constant-voltage mode; and control the cycling of the power switch to regulate the output voltage to equal the reference voltage of the constant-voltage mode during the constant-voltage mode. ### Claim 15 A switching power converter, comprising: a transformer having a primary winding and a secondary winding, wherein the secondary winding is coupled to an output node for an output voltage; a power switch in series with the primary winding; a controller configured to control a cycling of the power switch to regulate the output voltage to equal a maximum voltage during a constant-voltage mode, wherein the controller is further configured to: transition from the constant-voltage mode to a constant-power mode in response to an output current of the switching power converter being greater than a maximum current of the constant-voltage mode; control the cycling of the power switch to regulate the output current of the switching power converter to equal a first constant current while the output voltage of the switching power converter is within a first voltage range, wherein the first constant current is greater than the maximum current by a discrete current step, and calculate a first constant-power reference voltage by a division of a constant power of the constant-power mode by the first constant current, wherein the first voltage range includes the first constant-power reference voltage. ### Claim 16 (depends on 15) The switching power converter of claim 15, wherein the controller is further configured to: increment the first constant current by the discrete current step responsive to the output voltage being less than a minimum voltage of the first voltage range to provide a second constant current; determine a second constant-power reference voltage by a division of the constant power by the second constant current; and control the cycling of the power switch to regulate the output current of the switching power converter to equal the second constant current while the output voltage is within a second voltage range including the second constant-power reference voltage. ### Claim 17 (depends on 15) The switching power converter of claim 15, wherein the controller is further configured to: transition to a constant-current mode in response to the output current of the switching power converter being greater than a maximum constant current; and regulate the output current of the switching power converter to equal the maximum constant current during the constant-current mode. ### Claim 18 A switching power converter, comprising: a transformer having a primary winding and a secondary winding, wherein the secondary winding is coupled to an output node for an output voltage; a power switch in series with the primary winding; and a controller configured to: control a cycling of the power switch to regulate an output current of the switching power converter to equal a maximum constant current during a constant-current mode; transition from the constant-current mode to a constant-power mode in response to the output voltage being greater than a maximum voltage of the constant-current mode; control the cycling of the power switch to regulate the output current to equal a first constant current while the output voltage of the switching power converter is within a first voltage range, wherein the first constant current is less than the maximum constant current by a discrete current step, and calculate a first constant-power reference voltage by a division of a constant power of the constant-power mode by the first constant current, wherein the first voltage range includes the first constant-power reference voltage. ### Claim 19 (depends on 18) The switching power converter of claim 18, wherein the controller is further configured to: decrement the first constant current by the discrete current step responsive to the output voltage being greater than a maximum voltage of the first voltage range to provide a second constant current; determine a second constant-power reference voltage by a division of the constant power by the second constant current; and while the output voltage is within a second voltage range including the second constant-power reference voltage, control the cycling of the power switch to regulate the output current of the switching power converter to equal the second constant current. ### Claim 20 (depends on 18) The switching power converter of claim 18, wherein the controller is further configured to: transition to a constant-voltage mode in response to the output voltage being greater than a maximum constant voltage; and regulate the output voltage of the switching power converter to equal the maximum constant voltage during the constant-voltage mode.