Abstract: A control circuit, for controlling a switching converter having a primary switch, an energy storage component and a plurality of rectifiers, the control circuit having: a sample and hold circuit, configured to sample and hold a power source winding voltage provided by a power source winding of the energy storage component during when any one of the plurality of rectifiers is on, and to provide a sample&hold voltage based thereon; and a feedback circuit, configured to receive the sample&hold voltage and a power supply voltage of the control circuit, and to provide a feedback voltage based thereon; wherein the primary switch is controlled to be on and off based on the feedback voltage.

Abstract: An example method for cutting a plurality of lenticules from a donor cornea includes receiving a donor cornea, cutting a first layer of a first set of lenticules from the donor cornea, and cutting a second layer of a second set of lenticules from the donor cornea. The lenticules are cut according to a pattern that to maximizes the number of lenticules, thereby maximizing the number of implants from the single donor cornea. An example implant handling device includes a body. The body includes a flattened end configured to receive a corneal implant and keep the corneal implant from rolling or folding. The flattened end has a width and a height, the width being greater than the height. The body includes a slit opening to the flattened end, the slit opening configured to allow the corneal implant to pass into the flattened end.

Abstract: An over-current protection circuit has a current sensing circuit, an over-current comparing circuit, an isolation circuit and a control circuit. The current sensing circuit generates a current sensing signal based on a current flowing through an inductor of a voltage converter. The over-current comparing circuit receives the current sensing signal and generates a first over-current indication signal based on the current sensing signal. The isolation circuit receives the first over-current indication signal and generates a second over-current indication signal based on the first over-current indication signal. The control circuit receives the second over-current indication signal, and generates a control signal to control a switch of the voltage converter. The control circuit turns off the switch when the second over-current indication signal indicates that an over-current condition occurs.

Abstract: A controller of an isolated switching converter having a primary and secondary switch, the controller includes a valley detection circuit for providing a valley pulse signal in response to valleys of a resonant voltage, a pulse frequency modulation circuit for providing a pulse frequency modulation signal based on a feedback signal indicative of an output voltage, a primary on enable circuit for providing a primary on enable signal based on the pulse frequency modulation signal and valley pulse signal, a secondary logic circuit for generating a secondary control signal to control the secondary switch based on a primary off detection signal, a zero cross detection signal and the primary on enable signal, and a primary logic circuit for generating a primary control signal to control the primary switch based on a synchronous signal electrically isolated from the primary on enable signal.

Abstract: A power supply control circuit for controlling a charging process of a power supply capacitor to produce a power supply voltage to power a power control chip is disclosed. The power supply control circuit has a charging switch controlled by a charging control signal, and the power supply capacitor is coupled to an input voltage when the charging switch is on. The power supply control circuit further has a charging control circuit, configured to provide the charging control signal to control the charging switch based on the input voltage, the power supply voltage and a voltage threshold. Thus a high turns ratio of an auxiliary winding to a secondary winding is not necessary, high voltage devices are not needed and the power dissipation caused by the high voltage is also reduced.

Abstract: A controller of a switching converter includes an error amplifying circuit, a first comparison circuit, a valley detection circuit, a valley selection circuit and a frequency control circuit. The error amplifying circuit generates a compensation signal based on the difference between a reference signal and a feedback signal. The first comparison circuit compares the compensation signal with a modulation signal and generates a pulse frequency modulation signal. The valley detection circuit detects valleys of a resonant voltage of the switching converter and generates a valley pulse signal. The valley selection circuit generates a valley enable signal corresponding to a target valley number based on the pulse frequency modulation signal and the valley pulse signal. The frequency control circuit generates a frequency control signal to control the switching frequency of the first switch based on the valley enable signal and the valley pulse signal.

Abstract: A control circuit for a resonant circuit includes a resonant current detecting circuit, a current adjustment circuit and an on-time control circuit. The resonant current detecting circuit is configured to receive a resonant current, a first reference and a second reference, and to provide a detected current signal based on the resonant current, the first reference and the second reference. The current adjustment circuit is configured to receive the detected current signal and a charging reference, and to provide an on-time control signal based on the detected current signal and the charging reference. The on-time control circuit is configured to receive the on-time control signal and an on-time initial value, and to provide an on-time signal to control a switch of the resonant circuit based on the on-time control signal and the on-time initial value.

Abstract: A method to control a synchronous rectifier (SR) switch in a switching power supply circuit having an energy storage component coupled to the SR switch, the method is: generating a turning-ON control signal by comparing a drain-source sensing voltage of the SR switch with a turn ON threshold voltage; limiting an ON-time of the SR switch at least not less than a minimum on-time when the turning-ON control signal is asserted and an indicium signal having a first level indicating a fast mode; and removing the minimum on-time limitation to the SR switch and turning OFF the SR switch responsive to the drain-source sensing voltage of the SR switch exceeding a turn OFF threshold voltage when the turning-ON control signal is asserted and the indicium signal having a second level indicating a slow mode.

Abstract: A control circuit and control method for an interleaved switching converter having a first and second interleaved voltage regulating circuit. The control method is: controlling a first switch of the first voltage regulating circuit operating in quasi-resonant mode, turning ON a second switch of the second voltage regulating circuit after the first switch is turned ON for a half switching period, generating a current sensing signal by detecting a current flowing through the second switch, generating a peak signal, wherein the peak signal is adjusted when a voltage across the second switch is higher than a voltage reference at the time the second switch is turned ON, and turning OFF the second switch when the current sensing signal increases to the peak signal.

Abstract: A multi-converter switching power supply includes a first switching converter with a first output capacitor, a second switching converter with a second output capacitor, a bypass switch coupled across the second output capacitor, and a bypass control circuit for controlling the bypass switch. Input terminals of the first and switching converters are coupled in parallel, while output terminals of the first and switching converters are coupled in series to provide a total output voltage to a load. When detecting that the second output voltage approaches a negative voltage, the bypass control circuit turns on the bypass switch, so as to protect the second output capacitor from being damaged by a reverse DC voltage.

Abstract: An isolated switching regulator with adjustable power supplies is discussed. The isolated switching regulator includes a control circuit having a loop controller and a driver, which are powered by different power source based on different output voltage conditions.

Abstract: A switching mode power supply with improved power balance is discussed. It has a transformer, a primary circuit having a primary power switch coupled to a primary side of the transformer, and a plurality of secondary circuits coupled in parallel with each other at a secondary side of the transformer. A plurality of output voltages are provided at each of the secondary circuits; and each of the secondary circuits has a secondary power switch. If any of the output voltage deviates from a reference voltage, an ON time length of the corresponding secondary power switch is extended.

Abstract: A method for controlling a switching mode power supply is disclosed. An auxiliary winding feedback voltage of the switching mode power supply is sampled and held to obtain an auxiliary winding sample hold voltage. The auxiliary winding feedback voltage is sampled and held at an inflection point time to obtain an auxiliary winding inflection point voltage when the switching mode power supply operates in DCM or CRM. A secondary rectifier forward voltage signal is generated based on the auxiliary winding sample hold voltage and the auxiliary winding inflection point voltage before the switching mode power supply operates in CCM. A correction voltage is provided based on the secondary rectifier forward voltage signal when the switching power supply operates in CCM. An error amplifier signal is generated based on the correction voltage. The output power of the switching mode power supply is adjusted based on the error amplifier signal.

Abstract: An example method for cutting a plurality of lenticules from a donor cornea includes receiving a donor cornea, cutting a first layer of a first set of lenticules from the donor cornea, and cutting a second layer of a second set of lenticules from the donor cornea. The lenticules are cut according to a pattern that to maximizes the number of lenticules, thereby maximizing the number of implants from the single donor cornea. An example implant handling device includes a body. The body includes a flattened end configured to receive a corneal implant and keep the corneal implant from rolling or folding. The flattened end has a width and a height, the width being greater than the height. The body includes a slit opening to the flattened end, the slit opening configured to allow the corneal implant to pass into the flattened end.

Abstract: An isolated switching converter has a primary switch and a control circuit. The control circuit has a first sampling circuit, a second sampling circuit, a compensation circuit and a feedback control circuit. The first sampling circuit is coupled to an auxiliary winding of a transformer to receive a voltage on the auxiliary winding and is configured to generate a first feedback signal having an alternating current signal indicative of an output voltage. The second sampling circuit is coupled to the auxiliary winding through a first rectifier and is configured to generate a second feedback signal having a direct current signal indicative of the output voltage. The compensation circuit is configured to generate a compensation signal based on the first feedback signal, the second feedback signal and a reference threshold. The feedback control circuit is configured to generate a primary control signal of the primary switch based on the compensation signal.

Abstract: A control circuit of a zero current controlled dimming circuit having a high side power switch, a low side power switch and an inductor, having: an error circuit, providing a compensation signal based on a reference signal and a current sense signal indicative of an output current; a compensation circuit, providing a compensation off time signal based on the compensation signal and a peak value sample and hold signal indicative of a peak value of an inductor current; and a control signal generating circuit, providing a low side switch control signal to control the low side power switch based on the compensation off time signal, wherein after the inductor current decreases to zero, the low side power switch maintains on for a compensation off time period determined by the compensation off time signal.

Abstract: A power converter includes a first and a second transformers having different auxiliary winding voltage levels. A bias voltage supply circuit generates a bias supply voltage of an integrated circuit used to control the power converter, and includes a first and a second bias supply branches jointly coupled to a supply capacitor to provide the bias supply voltage. When the bias supply voltage is higher than a threshold voltage, the first bias supply branch to receive the one with lower level of the two auxiliary winding voltages is switched from a deactivation state to an activation state to provide the bias supply voltage, when the bias supply voltage is less than the threshold voltage, the second bias supply branch to receive the one with larger level of the two auxiliary winding voltages is switched from the deactivation state to the activation state to provide the bias supply voltage.

Abstract: A controller of an isolated switching converter having a primary and secondary switch, the controller includes a valley detection circuit for providing a valley pulse signal in response to valleys of a resonant voltage, a pulse frequency modulation circuit for providing a pulse frequency modulation signal based on a feedback signal indicative of an output voltage, a primary on enable circuit for providing a primary on enable signal based on the pulse frequency modulation signal and valley pulse signal, a secondary logic circuit for generating a secondary control signal to control the secondary switch based on a primary off detection signal, a zero cross detection signal and the primary on enable signal, and a primary logic circuit for generating a primary control signal to control the primary switch based on a synchronous signal electrically isolated from the primary on enable signal.

Abstract: A controller of a switching converter includes an error amplifying circuit, a first comparison circuit, a valley detection circuit, a valley selection circuit and a frequency control circuit. The error amplifying circuit generates a compensation signal based on the difference between a reference signal and a feedback signal. The first comparison circuit compares the compensation signal with a modulation signal and generates a pulse frequency modulation signal. The valley detection circuit detects valleys of a resonant voltage of the switching converter and generates a valley pulse signal. The valley selection circuit generates a valley enable signal corresponding to a target valley number based on the pulse frequency modulation signal and the valley pulse signal. The frequency control circuit generates a frequency control signal to control the switching frequency of the first switch based on the valley enable signal and the valley pulse signal.

Abstract: A control circuit, for controlling a switching converter having a primary switch, an energy storage component and a plurality of rectifiers, the control circuit having: a sample and hold circuit, configured to sample and hold a power source winding voltage provided by a power source winding of the energy storage component during when any one of the plurality of rectifiers is on, and to provide a sample&hold voltage based thereon; and a feedback circuit, configured to receive the sample&hold voltage and a power supply voltage of the control circuit, and to provide a feedback voltage based thereon; wherein the primary switch is controlled to be on and off based on the feedback voltage.