# US 2019/0356229 A1 · Cable compensation circuit and power supply including the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0356229 A1 - Document ID: US20190356229A1 - Status: Published application - Kind: A1 - Application number: 16/530,686 - Filed: 2019-08-02 - Published: 2019-11-21 - Earliest claimed: 2012-11-27 - Assignees: Semiconductor Components Industries, LLC - Applicants: Semiconductor Components Industries, LLC - Inventors: Gwanbon KOO; Taesung KIM - Web page: https://patentgrep.com/patent/US20190356229A1 ## CPC - H02M 3/33523: {with galvanic isolation between input and output of both the power stage and the feedback loop} - H02M 1/0025: {Arrangements for modifying reference values, feedback values or error values in the control loop of a converter} - 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 cable compensation circuit compensates a voltage drop in a cable coupled between a power supply and a load. The cable compensation circuit includes: a node where a voltage that depends on an input voltage of the power supply during a turn-on period of a power switch of the power supply and depends on an output voltage of the power supply during a turn-off period of the power switch is generated; a sensing RC filter generating a sense voltage that depends on a diode current by filtering the voltage of the node; and an averaging RC filter generating an average voltage by averaging the sense voltage. ## Claims ### Claim 1 A compensation circuit for compensating for a voltage drop in a cable coupled between a power supply and a load, the compensation circuit comprising: a sensing resistive-capacitive (RC) filter including a first capacitor and configured to receive a voltage from an auxiliary winding of the power supply and generate a sense voltage by RC filtering the received voltage; and an averaging filter including a second capacitor and configured to generate an average voltage by averaging the sense voltage, wherein the power supply comprises a transformer including a primary winding, a secondary winding, and the auxiliary winding, a power switch coupled through the primary winding to an input voltage, and a rectifying diode coupled between the secondary winding and the output voltage, wherein the compensation circuit provides the average voltage to a feedback circuit of the power supply, and wherein the power supply uses the average voltage to control the power switch. ### Claim 2 (depends on 1) The compensation circuit of claim 1, wherein the sensing RC filter comprises: a first resistor coupled between the auxiliary winding and a first end of the first capacitor, wherein the sense voltage is generated at the first end of the first capacitor. ### Claim 3 (depends on 2) The compensation circuit of claim 2, wherein the sensing RC filter further comprises a clamping diode coupled in parallel with the first capacitor to clamp the sense voltage to a forward voltage of the clamping diode. ### Claim 4 (depends on 1) The compensation circuit of claim 1, wherein switching of the power switch causes a slope of the sense voltage to change. ### Claim 5 (depends on 4) The compensation circuit of claim 4, wherein the voltage received by the sensing RC filter is proportional to the input voltage during a turn-on period of the power switch, and is proportional to the output voltage during the turn-off period of the power switch. ### Claim 6 (depends on 1) The compensation circuit of claim 1, wherein the averaging filter comprises: a second resistor coupled between the sense voltage and a first end of the second capacitor, wherein the average voltage is generated at the first end of the second capacitor. ### Claim 7 (depends on 1) The compensation circuit of claim 1, wherein a magnitude of the average voltage corresponds to a magnitude of a load current supplied by the power supply to the load. ### Claim 8 (depends on 1) The compensation circuit of claim 1, wherein in response to an increase in the magnitude of the average voltage, the power supply circuit increases a magnitude of the output voltage. ### Claim 9 A power supply comprising: a transformer including a primary winding, a secondary winding, and an auxiliary winding; a power switch coupled through the primary winding to an input voltage; a rectifying diode coupled between the secondary winging and an output voltage for supplying to a load; a gate driver configured to control a switching operation of the power switch based on a feedback signal; a cable compensation circuit configured to: receive an auxiliary voltage from the auxiliary winding, generate, on a first capacitor, a sense voltage by resistive-capacitive (RC) filtering of the auxiliary voltage, generate, on a second capacitor, and average voltage by averaging the sense voltage; and a feedback circuit configured to generate a feedback signal based on the output voltage and the average voltage. ### Claim 10 (depends on 9) The power supply of claim 9, wherein the cable compensation circuit further comprises a first resistor coupled between the first capacitor and the auxiliary winding. ### Claim 11 (depends on 10) The power supply of claim 10, wherein the cable compensation circuit further comprises a clamping diode coupled in parallel with the first capacitor to clamp the sense voltage to a forward voltage of the clamping diode. ### Claim 12 (depends on 9) The power supply of claim 9, wherein switching of the power switch causes a slope of the sense voltage to change. ### Claim 13 (depends on 9) The power supply of claim 9, wherein the auxiliary voltage is proportional to the input voltage during a turn-on period of the power switch and is proportional to the output voltage during a turn-off period of the power switch. ### Claim 14 (depends on 9) The power supply of claim 9, wherein the cable compensation circuit further comprises a second resistor coupled between the second capacitor and the sense voltage. ### Claim 15 (depends on 9) The power supply of claim 9, wherein a magnitude of the average voltage is proportional to a magnitude of a load current supplied by the power supply to the load. ### Claim 16 (depends on 9) The power supply of claim 9, wherein in response to an increase in the magnitude of the average voltage, the power supply circuit increases a magnitude of the output voltage. ### Claim 17 (depends on 9) The power supply of claim 9, wherein the feedback circuit comprises a shunt regulator configured to control a sink current according to a voltage of a reference end, a third resistor coupled between the reference end and the output voltage, and a fourth resistor coupled between the reference end and ground, and wherein the cable compensation circuit further comprises a fifth resistor coupled between the reference end and the average voltage. ### Claim 18 A method of compensating for a voltage drop in a cable coupled between a power supply and a load, the method comprising: generating, on an auxiliary winding of a transformer, an auxiliary voltage that is proportional to an input voltage of the power supply during a turn-on period of a power switch and is proportional to an output voltage of the power supply during a turn-off period of the power switch, wherein the output voltage is coupled through a rectifying diode to a secondary winding of the transformer, and wherein the input voltage is coupled through a primary winding of the transformer to the power switch; generating, using a sensing resistive-capacitive (RC) filter including a first capacitor, a sense voltage by RC filtering of the auxiliary voltage; and generating, using an averaging filter including a second capacitor, an average voltage by averaging a voltage value of the sense voltage, and controlling the power switch to increase a magnitude of the output voltage in response to an increase in the magnitude of the average voltage. ### Claim 19 (depends on 18) The method of claim 18, wherein a magnitude of the average voltage corresponds to a magnitude of a load current supplied by the power supply to the load. ### Claim 20 (depends on 18) The method of claim 18, further comprising clamping, using a clamping diode coupled in parallel with the first capacitor, the sense voltage to a forward voltage of the clamping diode.