# US 10,312,818 B2 · Control circuit and method for programming an output voltage of a power converter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,312,818 B2 - Document ID: US10312818B2 - Status: Granted - Kind: B2 - Application number: 16/012,247 - Filed: 2018-06-19 - Published: 2018-10-18 - Granted: 2019-06-04 - Earliest claimed: 2015-01-22 - Assignees: Richtek Technology Corporation - Applicants: Richtek Technology Corporation - Inventors: Isaac Y. Chen - Web page: https://patentgrep.com/patent/US10312818B2 ## CPC - H02M 3/33523: {with galvanic isolation between input and output of both the power stage and the feedback loop} - H02M 3/33515: {with digital control} - 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 power converter determines a feedback signal according to a voltage signal related to an output voltage of the power converter and a reference voltage, thereby regulating the output voltage. A control circuit and method for programming the output voltage of the power converter utilize an offset current generator to inject a current or sink a current for changing the voltage signal or the reference signal, thereby adjusting the output voltage. As a result, it gets rid of complicated circuitry but provides more steps adjustment, which reduces related costs. ## Claims ### Claim 1 A control circuit for programming an output voltage of a power converter including a feedback loop configured to operably provide a feedback signal related to the output voltage so as to regulate the output voltage, the control circuit comprising: a voltage divider configured to operably divide the output voltage to generate a first voltage signal; an offset resistor having a first terminal and a second terminal; wherein, the first terminal of the offset resistor is coupled to the voltage divider for receiving the first voltage signal and the second terminal of the offset resistor is configured to operably output a second voltage signal for controlling the feedback signal; and an offset current generator coupled to the second terminal of the offset resistor and configured to operably inject a first current to the offset resistor or sink a second current from the offset resistor so as to offset the first voltage signal to generate the second voltage signal; wherein, the offset current generator adjusts the first current or the second current so as to adjust the second voltage signal, thereby changing the feedback signal and adjusting the output voltage. ### Claim 2 (depends on 1) The control circuit of claim 1, wherein the voltage divider comprises a pair of resistors that are in a serial connection configured to operably divide the output voltage to generate the first voltage signal. ### Claim 3 (depends on 1) The control circuit of claim 1, wherein the offset current generator comprises: a decoder configured to operably decode a first digital signal; and a first digital to analog converter, coupled to the decoder and the second terminal of the offset resistor, configured to operably inject the first current to the offset resistor or sink the second current from the offset resistor according to outputs of the decoder. ### Claim 4 (depends on 3) The control circuit of claim 3, the outputs of the decoder includes a first control signal, a second control signal, a first switch signal, and a second switch signal. ### Claim 5 (depends on 4) The control circuit of claim 4, wherein the first digital to analog converter comprises: a first variable current source configured to operably adjust the first current according to the first control signal; a first switch coupled between the first variable current source and the second terminal of the offset resistor; wherein, the first switch will be turned on or turned off according to the first switch signal; a second variable current source configured to operably adjust the second current according to the second control signal; and a second switch coupled between the second variable current source and the second terminal of the offset resistor; wherein, the second switch will be turned on or turned off according to the second switch signal. ### Claim 6 (depends on 3) The control circuit of claim 3 further comprising: a transistor coupled to the feedback loop; wherein, a current that is passing through the transistor determines the feedback signal; a second digital to analog converter having a first output terminal to provide a reference voltage; and an error amplifier having a first input terminal coupled to the second terminal of the offset resistor and the first digital to analog converter, a second input terminal coupled to the second digital to analog converter, and an output terminal coupled to a control terminal of the transistor; wherein, the error amplifier controls the current that is passing through the transistor according to a difference between the second voltage signal and the reference voltage so as to determine the feedback signal. ### Claim 7 (depends on 6) The control circuit of claim 6, wherein a resolution of the first digital to analog converter is lower than a resolution of the second digital to analog converter. ### Claim 8 (depends on 6) The control circuit of claim 6, further comprising a microcontroller coupled to the second digital to analog converter and the decoder. ### Claim 9 (depends on 8) The control circuit of claim 8, wherein the microcontroller comprises a program memory and a data memory and generates the first digital signal to the decoder and the second digital signal to the second digital to analog converter to determine the reference voltage according to information saved in the program memory and the data memory. ### Claim 10 (depends on 6) The control circuit of claim 6, wherein the second digital to analog converter further includes a second output terminal configured to operably provide a threshold. ### Claim 11 (depends on 10) The control circuit of claim 10, further comprising a comparator, coupled to the second terminal of the offset resistor and the second output terminal of the second digital to analog converter, configured to operably compare the second voltage signal with the threshold and generate a protecting signal when the second voltage signal is higher than the threshold so as to turn off the power converter to achieve an overvoltage protection. ### Claim 12 (depends on 9) The control circuit of claim 9, further comprising a comparator, coupled to the second terminal of the offset resistor and the second output terminal of the second digital to analog converter, configured to operably compare the second voltage signal with the threshold and generate a protecting signal when the second voltage signal is lower than the threshold so as to turn off the power converter to achieve an under voltage protection. ### Claim 13 A control method for programming an output voltage of a power converter including a feedback loop configured to operably provide a feedback signal related to the output voltage so as to regulate the output voltage, the control method comprising the steps of: dividing the output voltage to generate a first voltage signal to a first terminal of an offset resistor; injecting a first current to a second terminal of the offset resistor or sinking a second current from the second terminal of the offset resistor, thereby offsetting the first voltage signal to generate a second voltage signal to control the feedback signal; and adjusting the first current or the second current so as to adjust the second voltage signal, thereby changing the feedback signal and adjusting the output voltage. ### Claim 14 (depends on 13) The method of claim 13, further comprising a step of controlling the feedback signal according to a difference of the second voltage signal and a reference voltage. ### Claim 15 (depends on 13) The method of claim 13, further comprising a step of generating a protecting signal when the second voltage signal is higher than a threshold to turn off the power converter so as to achieve an overvoltage protection. ### Claim 16 (depends on 13) The method of claim 13, further comprising a step of generating a protecting signal when the second voltage signal is lower than a threshold to turn off the power converter so as to achieve an under voltage protection.