# US 10,374,515 B2 · Switched mode power supply with dynamic frequency foldback > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,374,515 B2 - Document ID: US10374515B2 - Status: Granted - Kind: B2 - Application number: 16/177,723 - Filed: 2018-11-01 - Published: 2019-03-07 - Granted: 2019-08-06 - Earliest claimed: 2016-10-07 - Assignees: Semiconductor Components Industries, LLC - Applicants: Semiconductor Components Industries, LLC - Inventors: Ajay Karthik Hari; Bryan Wayne McCoy; Thomas Ciccone - Web page: https://patentgrep.com/patent/US10374515B2 ## CPC - H02M 3/158: including plural semiconductor devices as final control devices for a single load - H02J 7/00: Circuit arrangements for charging or discharging batteries or for supplying loads from batteries - H02M 1/126: {using passive filters} - H02M 1/44: Circuits or arrangements for compensating for electromagnetic interference in converters or inverters - H02M 3/33523: {with galvanic isolation between input and output of both the power stage and the feedback loop} - H02M 1/0032: {Control circuits allowing low power mode operation, e.g. in standby mode} - H02M 1/0054: {Transistor switching losses (periodically suspending operation of switching converter in low power mode H02M1/0035)} - H02M 1/344: {Active dissipative snubbers} - Y02B 40/00: Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers - Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes - 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) - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract In one form, a switched mode power supply controller with frequency foldback includes a pulse width modulator responsive to a clock signal to generate a drive signal having a pulse width that varies in response to a feedback signal, and a variable frequency oscillator having a first input for receiving the feedback signal, a control input for receiving a control signal defining a foldback starting frequency, a foldback ending frequency, a foldback starting voltage, and a foldback ending voltage, and an output for providing the clock signal having a variable frequency that varies over a range between the foldback starting frequency and the foldback ending frequency as the feedback signal varies between the foldback starting voltage and the foldback ending voltage, respectively. The control signal is user programmable for at least one of the foldback starting frequency, the foldback ending frequency, the foldback starting voltage, and the foldback ending voltage. ## Claims ### Claim 1 A switched mode power supply controller with frequency foldback, comprising: a pulse width modulator responsive to a clock signal to generate a drive signal having a pulse width that varies in response to a feedback signal; and a variable frequency oscillator having a first input for receiving said feedback signal, a control input for receiving a control signal defining a foldback starting frequency, a foldback ending frequency, a foldback starting voltage, and a foldback ending voltage, and an output for providing said clock signal having a variable frequency that varies over a range between said foldback starting frequency and said foldback ending frequency as said feedback signal varies between said foldback starting voltage and said foldback ending voltage, respectively, wherein said control signal is user programmable for at least one of said foldback starting frequency, said foldback ending frequency, said foldback starting voltage, and said foldback ending voltage. ### Claim 2 (depends on 1) The switched mode power supply controller of claim 1, wherein said control signal is user programmable for said foldback ending voltage and said foldback ending frequency. ### Claim 3 (depends on 2) The switched mode power supply controller of claim 2, wherein said control signal is set internally for said foldback starting frequency. ### Claim 4 (depends on 3) The switched mode power supply controller of claim 3, wherein said foldback starting frequency is set internally above a human audible frequency. ### Claim 5 (depends on 4) The switched mode power supply controller of claim 4, wherein said foldback starting frequency is set internally to 25 kilohertz (kHz). ### Claim 6 (depends on 3) The switched mode power supply controller of claim 3, wherein said control signal is further set internally for said foldback starting voltage. ### Claim 7 (depends on 6) The switched mode power supply controller of claim 6, further comprising a reference level generator having an output for defining said foldback starting frequency, wherein said control input of said variable frequency oscillator is further coupled to said output of said reference level generator. ### Claim 8 (depends on 2) The switched mode power supply controller of claim 2, wherein said pulse width modulator and said variable frequency oscillator are combined in an integrated circuit comprising a plurality of terminals, said plurality of terminals comprising: a first programmable input terminal for receiving a first input signal defining said foldback ending frequency; and a second programmable input terminal for receiving a second input signal defining said foldback ending voltage, wherein said control input of said variable frequency oscillator is coupled to said first programmable input terminal and to said second programmable input terminal. ### Claim 9 (depends on 1) The switched mode power supply controller of claim 1, wherein when said feedback signal is less than said foldback starting voltage, the switched mode power supply controller operates in a skip mode. ### Claim 10 (depends on 1) The switched mode power supply controller of claim 1, wherein when said feedback signal is greater than said foldback ending voltage, the switched mode power supply controller operates in a fixed frequency mode in which said pulse width modulator switches at said foldback ending frequency. ### Claim 11 (depends on 1) The switched mode power supply controller of claim 1, wherein when said feedback signal is greater than said foldback ending voltage, the switched mode power supply controller operates in a variable frequency mode in which said pulse width modulator switches at a frequency that depends on another condition. ### Claim 12 (depends on 1) The switched mode power supply controller of claim 1, wherein said control signal is user programmable for a plurality of said foldback starting frequency, said foldback ending frequency, said foldback starting voltage, and said foldback ending voltage. ### Claim 13 A switched mode power converter with frequency foldback, comprising: an inductive element having an input for receiving an input voltage, and an output for providing an output voltage; a switch having a first current electrode coupled to a terminal of said inductive element, a second current electrode coupled to a power supply terminal, and a control electrode for receiving a drive signal; a feedback circuit having an input coupled to said output of said inductive element, and an output for providing a feedback signal; and a switched mode power supply controller, comprising: a pulse width modulator responsive to a clock signal having an output coupled to said control electrode of said switch, wherein said pulse width modulator generates said drive signal with a pulse width that varies in response to said feedback signal; and a variable frequency oscillator having a first input for receiving said feedback signal, a control input for receiving a control signal defining a foldback starting frequency, a foldback ending frequency, a foldback starting voltage, and a foldback ending voltage, and an output for providing said clock signal having a variable frequency that varies over a range between said foldback starting frequency and said foldback ending frequency as said feedback signal varies between said foldback starting voltage and said foldback ending voltage, respectively, wherein said switched mode power converter programs at least one of said foldback starting frequency, said foldback ending frequency, said foldback starting voltage, and said foldback ending voltage through at least one terminal of said switched mode power supply controller. ### Claim 14 (depends on 13) The switched mode power converter of claim 13, wherein the switched mode power converter programs said foldback ending voltage and said foldback ending frequency. ### Claim 15 (depends on 14) The switched mode power converter of claim 14, wherein said switched mode power supply controller internally sets said foldback starting frequency. ### Claim 16 (depends on 15) The switched mode power converter of claim 15, wherein said switched mode power supply controller internally sets said foldback starting frequency above a human audible frequency. ### Claim 17 (depends on 16) The switched mode power converter of claim 16, wherein said switched mode power supply controller internally sets said foldback starting frequency to 25 kilohertz (kHz). ### Claim 18 (depends on 15) The switched mode power converter of claim 15, wherein said switched mode power supply controller further internally sets said control signal for said foldback starting voltage. ### Claim 19 (depends on 18) The switched mode power converter of claim 18, further comprising a reference level generator having an output for defining said foldback starting frequency, wherein said control input of said variable frequency oscillator is further coupled to said output of said reference level generator. ### Claim 20 (depends on 14) The switched mode power converter of claim 14, wherein said switched mode power supply controller is an integrated circuit comprising a plurality of terminals, said plurality of terminals comprising: a first programmable input terminal for receiving a first input signal defining said foldback ending frequency; and a second programmable input terminal for receiving a second input signal defining said foldback ending voltage, wherein said control input of said variable frequency oscillator is coupled to said first programmable input terminal and to said second programmable input terminal. ### Claim 21 (depends on 20) The switched mode power converter of claim 20, further comprising: a first resistor coupled to said first programmable input terminal for defining said foldback ending frequency; and a second resistor coupled to said second programmable input terminal for defining said foldback ending voltage. ### Claim 22 (depends on 13) The switched mode power converter of claim 13, wherein when said feedback signal is less than said foldback starting voltage, the switched mode power supply controller operates in a skip mode. ### Claim 23 (depends on 13) The switched mode power converter of claim 13, wherein when said feedback signal is greater than said foldback ending voltage, the switched mode power supply controller operates in a fixed frequency mode in which said pulse width modulator switches at said foldback ending frequency. ### Claim 24 (depends on 13) The switched mode power converter of claim 13, wherein said control signal is programmable for a plurality of said foldback starting frequency, said foldback ending frequency, said foldback starting voltage, and said foldback ending voltage. ### Claim 25 (depends on 13) The switched mode power converter of claim 13, wherein when said feedback signal is greater than said foldback ending voltage, said switched mode power supply controller operates in a variable frequency mode in which said pulse width modulator switches at a frequency that depends on another condition. ### Claim 26 (depends on 25) The switched mode power converter of claim 25, wherein the switched mode power converter is an active clamp flyback (ACF) converter. ### Claim 27 (depends on 26) The switched mode power converter of claim 26, wherein said frequency depends on a magnetization condition of a primary winding of a transformer, and an on time of said drive signal varies with an amount of output current provided to a load. ### Claim 28 A method for generating a drive signal for a switch in a switched mode power supply comprising: receiving a feedback signal that is representative of an output voltage; and generating a pulse width modulated signal in response to a clock signal and said feedback signal; receiving a programmable control signal for determining a foldback starting frequency, a foldback ending frequency, a foldback starting voltage, and a foldback ending voltage, said receiving comprising receiving at least one of said foldback starting frequency, said foldback ending frequency, said foldback starting voltage, and said foldback ending voltage from a user; and varying a frequency of said clock signal over a range between said foldback starting frequency and said foldback ending frequency as said feedback signal varies between said foldback starting voltage and said foldback ending voltage, respectively. ### Claim 29 (depends on 28) The method of claim 28 wherein said receiving further comprises: receiving a plurality of said foldback starting frequency, said foldback ending frequency, said foldback starting voltage, and said foldback ending voltage from the user. ### Claim 30 (depends on 29) The method of claim 29, wherein said receiving further comprises: receiving said foldback ending voltage and said foldback ending frequency from the user. ### Claim 31 (depends on 29) The method of claim 29, wherein said receiving further comprises: setting said foldback starting frequency to a fixed frequency. ### Claim 32 (depends on 31) The method of claim 31, wherein said setting said foldback starting frequency to said fixed frequency further comprises: setting said foldback starting frequency to a frequency above a human audible frequency. ### Claim 33 (depends on 32) The method of claim 32, wherein said setting said foldback starting frequency to said frequency above said human audible frequency comprises setting said foldback starting voltage to 25 kilohertz (kHz). ### Claim 34 (depends on 31) The method of claim 31, wherein said receiving further comprises: setting said foldback starting voltage to a fixed voltage. ### Claim 35 (depends on 29) The method of claim 29, further comprising generating said pulse width modulated signal in a skip mode when said feedback signal is less than said foldback starting voltage. ### Claim 36 (depends on 29) The method of claim 29, further comprising generating said pulse width modulated signal in a fixed frequency mode when said feedback signal is greater than said foldback ending voltage.