Abstract: Input AC voltage sensing for a flyback circuit. The flyback circuit is configured as “primary-high”, namely a primary switch of the flyback circuit is positioned “high” to receive an input AC voltage through a first rectifying circuit. A primary winding of the flyback circuit is coupled to a primary ground reference. A voltage sensing circuit has a processing circuit and a first sensing resistor. The processing circuit has a first terminal coupled to the input AC source through a second rectifying circuit, a second terminal coupled to the primary ground reference and an output terminal. The processing circuit subtracts a voltage at the second terminal from a voltage at the first terminal to obtain a differential voltage, which is then sampled and held as an input AC voltage sensing signal.

Abstract: A switching converter with quasi-resonant control having a switch and an energy storage component, comprising a peak current regulating circuit configured to provide a peak current regulating signal to regulate a peak current signal or a current sense signal, wherein the peak current regulating signal is adjusted when non-CCM (Current Continuous Mode) and non-valley-switching are detected.

Abstract: A switching power supply circuit with synchronous rectifier has an energy storage component, a rectifier switch coupled to a secondary side of the energy storage component, and a secondary side control circuit. The secondary side control circuit provides a driving signal to control the rectifier switch. When the drain-source voltage across the rectifier switch is less than a first threshold value, the secondary side control circuit controls the driving signal to be a maximum voltage to control the rectifier switch being fully on for a predetermined duration. After a predetermined duration, the secondary side control circuit adjusts the voltage of the driving signal based on the drain-source voltage across the rectifier switch and a second threshold value.

Abstract: In some embodiments, the present invention provides tissue compositions including a first silk scaffold comprising a plurality of epithelial cells, a second silk scaffold comprising a plurality of stromal cells, and a plurality of neurons. In some embodiments, provided compositions can function as physiologically relevant corneal model systems for, inter alia, testing of therapeutics for corneal disease and/or injury and production of functional corneal tissue (e.g., for transplant, etc). The present invention also provides methods for making and using provided compositions.

Abstract: A synchronous switching converter with an energy storage component and a synchronous rectifier coupled to the energy storage component, having: a secondary control circuit configured to receive a slew rate threshold adjusting signal and a voltage across the synchronous rectifier, and to provide a secondary control signal; wherein the secondary control circuit detects a slew rate of the voltage across the synchronous rectifier, and maintains the synchronous rectifier being off when the slew rate of the voltage across the synchronous rectifier is lower than a slew rate threshold.

Abstract: A switching converter with quasi-resonant control having a switch and an energy storage component, comprising a peak current regulating circuit configured to provide a peak current regulating signal to regulate a peak current signal or a current sense signal, wherein the peak current regulating signal is adjusted when non-CCM (Current Continuous Mode) and non-valley-switching are detected.

Abstract: A control method of frequency jittering with a switching mode power supply, comprising: turning on and off a power switch of the switching mode power supply alternatively; updating a peak current signal of the switching mode power supply at a beginning of an on time of the power switch according to a length of a switching period before the beginning of the on time of the power switch, wherein the peak current signal varies as the length of the switching period changes.

Abstract: A control method of frequency jittering with a switching mode power supply, comprising: turning on and off a power switch of the switching mode power supply alternatively; updating a peak current signal of the switching mode power supply at a beginning of an on time of the power switch according to a length of a switching period before the beginning of the on time of the power switch, wherein the peak current signal varies as the length of the switching period changes.

Abstract: An isolated switching mode power supply, having: an input terminal; an output terminal; a transformer having a primary winding and a secondary winding; a primary power switch coupled to the primary winding; a secondary power switch coupled between the secondary winding and the output terminal of the power supply; a secondary controller configured to generate a frequency modulation signal based on the output voltage and the first feedback signal; a coupled device configured to provide a frequency control signal based on the output voltage and the frequency modulation signal; and a primary controller configured to provide a switching signal to control the primary power switch based on the current sense signal and the frequency control signal.

Abstract: A peak sample circuit for AC voltage, including: a rectifier coupled to receive an AC voltage and to rectify the AC voltage to generate a rectified signal; a delay circuit coupled to receive the rectified signal and to delay the rectified signal to generate a delayed rectified signal; a comparison circuit coupled to receive the delayed rectified signal and to generate a square signal based on the comparison of the rectified signal and the delayed rectified signal; and a sample output circuit coupled to receive the rectified signal, wherein the sample output circuit samples the rectified signal under the control of the square signal and provides a peak sample signal representative of the peak value of the AC voltage.

Abstract: A controller of an isolated switching converter includes an error amplifying circuit, a modulation signal generator, a first comparison circuit, a primary off detection circuit, a secondary logic circuit, an isolation circuit and a primary logic 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 generated by the modulation signal generator and generates a first comparison signal. The primary off detection circuit detects whether the primary switch is off and generates a primary off detection signal. The secondary logic circuit generates a secondary control signal to control the secondary switch based on the first comparison signal and the primary off detection signal. The isolation circuit receives the first comparison signal and generates a synchronous signal electrically isolated from the first comparison signal.

Abstract: A switching mode power supply (SMPS) includes a transformer having a primary winding, a secondary winding for providing an output voltage and an auxiliary winding, a primary switch coupled to the primary winding, a secondary rectifying diode coupled to the secondary winding and a secondary switch connected in parallel with the secondary rectifying diode. A control method used in the SMPS includes: comparing a voltage across the secondary switch with a first secondary threshold and a second secondary threshold and generating a hysteresis comparison signal; timing based on the hysteresis comparison signal; comparing the voltage across the secondary switch with a third secondary threshold when the timing period reaches a first predetermined time; turning ON the secondary switch when the voltage across the secondary switch is less than a third secondary threshold; and turning on the primary switch when the conduction of the secondary switch is detected.

Abstract: An AC signal detector having: a rectify circuit having a first input terminal and a second input terminal configured to receive an AC signal, and an output terminal configured to provide a rectified signal based on the AC signal; a detecting circuit having an input terminal coupled to the output terminal of the rectify circuit to receive the rectified signal, and an output terminal configured to provide a square signal based on the rectified signal; and an unplug indicate circuit having an input terminal coupled to the detecting circuit to receive the square signal, and an output terminal configured to provide an unplug indicate signal based on the square signal.

Abstract: A switching mode power supply, having: an input port; an output port; an energy storage component and a pair of power switches coupled between input port and the output port; an error amplifier configured to generate an amplified error signal based on the feedback signal and the reference signal; an error comparator configured to generate a frequency control signal based on the amplified error signal and the first sawtooth signal; a peak current generator configured to generate a peak current signal based on the frequency control signal; a peak current comparator configured to generate a current limit signal based on the peak current signal and the current sense signal; and a logic circuit configured to generate a switching signal to control the power switches based on the frequency control signal and the current limit signal.

Abstract: A switching mode power supply (SMPS) includes a transformer having a primary winding, a secondary winding for providing an output voltage and an auxiliary winding, a primary switch coupled to the primary winding, a secondary rectifying diode coupled to the secondary winding and a secondary switch connected in parallel with the secondary rectifying diode. A control method used in the SMPS includes: comparing a voltage across the secondary switch with a first secondary threshold and a second secondary threshold and generating a hysteresis comparison signal; timing based on the hysteresis comparison signal; comparing the voltage across the secondary switch with a third secondary threshold when the timing period reaches a first predetermined time; turning ON the secondary switch when the voltage across the secondary switch is less than a third secondary threshold; and turning on the primary switch when the conduction of the secondary switch is detected.

Abstract: An isolated switching mode power supply, having: a transformer having a primary winding, a secondary winding and a third winding; a current limit comparator configured to provide a current limit signal based on the current sense signal and the peak current signal; a logic circuit configured to provide a logic control signal based on the frequency control signal and the current limit signal; a startup control circuit configured to generate a startup control signal based on the current sense signal; a load detecting circuit configured to provide a load detecting signal based on the second feedback signal and the switching signal; and a selector configured to provide the logic control signal or the startup control signal based on the load detecting signal.

Abstract: A controller of an isolated switching converter includes an error amplifying circuit, a modulation signal generator, a first comparison circuit, a primary off detection circuit, a secondary logic circuit, an isolation circuit and a primary logic 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 generated by the modulation signal generator and generates a first comparison signal. The primary off detection circuit detects whether the primary switch is off and generates a primary off detection signal. The secondary logic circuit generates a secondary control signal to control the secondary switch based on the first comparison signal and the primary off detection signal. The isolation circuit receives the first comparison signal and generates a synchronous signal electrically isolated from the first comparison signal.

Abstract: A peak sample circuit for AC voltage, including: a rectifier coupled to receive an AC voltage and to rectify the AC voltage to generate a rectified signal; a delay circuit coupled to receive the rectified signal and to delay the rectified signal to generate a delayed rectified signal; a comparison circuit coupled to receive the delayed rectified signal and to generate a square signal based on the comparison of the rectified signal and the delayed rectified signal; and a sample output circuit coupled to receive the rectified signal, wherein the sample output circuit samples the rectified signal under the control of the square signal and provides a peak sample signal representative of the peak value of the AC voltage.

Abstract: A switching mode power supply with improved peak current control is disclosed. A varying reference signal is adopted to limit the peak current in the energy storage component. The varying reference signal is an exponential function of a time period when a power switch is ON, wherein the power switch is coupled to the energy storage component. The varying reference signal may be generated by a circuit comprising a RC circuit and one or several voltage sources.

Abstract: An AC signal detector having: a rectify circuit having a first input terminal and a second input terminal configured to receive an AC signal, and an output terminal configured to provide a rectified signal based on the AC signal; a detecting circuit having an input terminal coupled to the output terminal of the rectify circuit to receive the rectified signal, and an output terminal configured to provide a square signal based on the rectified signal; and an unplug indicate circuit having an input terminal coupled to the detecting circuit to receive the square signal, and an output terminal configured to provide an unplug indicate signal based on the square signal.