Abstract: A standby method for a switching power supply may be applied to a switching power supply provided with an optical coupler circuit. The method includes: upon detecting a mode control signal indicating that a load device power supply demand is greater than a preset value, entering a first mode, and controlling output voltage of the switching power supply by means of an optical coupler circuit; and upon detecting a mode control signal indicating that the load device power supply demand is less than or equal to the preset value, entering a second mode, turning off a bias current of the optical coupler circuit, and controlling the output of the switching power supply by means of a driving pulse signal, so as to reduce bias currents of a primary side and a secondary side of the switching power supply, and reduce standby power consumption of the switching power supply.

Abstract: Aa switching power supply is provided. The switching power supply may include: a protocol circuit disposed on a secondary side of the switching power supply and configured to detect a power supply demand of a load device connected to the protocol circuit; a synchronous rectifier circuit disposed on the secondary side of the switching power supply and configured to control a rectifier power tube; and a signal transmission circuit disposed between the protocol circuit and the synchronous rectifier circuit and configured to transmit a signal between the protocol circuit and the synchronous rectifier circuit.

Abstract: A circuit for supplying power to a switching power supply control circuit based on an auxiliary winding includes: an auxiliary winding, a switching transistor, a low dropout voltage regulator (LDO), a first diode, a second diode, a forward energy storage capacitor, and a flyback energy storage capacitor, where the auxiliary winding, the flyback energy storage capacitor, and the switching transistor form a flyback energy storage loop to charge the flyback energy storage capacitor, and the auxiliary winding, the flyback energy storage capacitor, and the switching transistor form a flyback energy storage loop to charge the flyback energy storage capacitor. In a forward state, if the voltage of the forward energy storage capacitor is less than the voltage at an output terminal of the LDO, the flyback energy storage capacitor supplies power, or if the voltage of the forward energy storage capacitor is greater, the forward energy storage capacitor supplies power.

Abstract: An overtemperature protection circuit used for a switching power supply having a power switch includes a control circuit coupled to the power switch and configured to control, by a control terminal, on and off of the power switch, the control circuit having a sampling terminal for sampling a demagnetization signal of the switching power supply; and a temperature measurement circuit coupled between the control terminal and the sampling terminal. While the power switch is on, the control circuit clamps voltages at the control terminal and the sampling terminal to form a potential difference, thereby performing overtemperature protection of the switching power supply by a change in a current flowing through the temperature measurement circuit. While the power switch is off, a direction of a current flowing through the temperature measurement circuit is unidirectional from the control terminal to the sampling terminal.

Abstract: A system for controlling a skip mode of a switching power supply and a PWM controller are provided. The system includes a feedback signal detection circuit configured to detect an output voltage of the switching power supply and generate a feedback signal related to the output voltage; a primary winding sampling circuit coupled with a primary winding of the switching power supply and configured to sample a sampling voltage of the primary winding; a skip mode soft control circuit configured to receive the feedback signal and output an electrical signal; and a comparison circuit configured to determine a threshold for the sampling voltage, where the skip mode is activated when the feedback signal is greater than a soft activation voltage threshold, and the skip mode is pre-exited when the feedback signal is less than a predetermined voltage threshold and greater than a soft exit voltage threshold.

Abstract: A system for controlling a skip mode of a switching power supply and a PWM controller are provided. The system includes a feedback signal detection circuit configured to detect an output voltage of the switching power supply and generate a feedback signal related to the output voltage; a primary winding sampling circuit coupled with a primary winding of the switching power supply and configured to sample a sampling voltage of the primary winding; a skip mode soft control circuit configured to receive the feedback signal and output an electrical signal; and a comparison circuit configured to determine a threshold for the sampling voltage, where the skip mode is activated when the feedback signal is greater than a soft activation voltage threshold, and the skip mode is pre exited when the feedback signal is less than a predetermined voltage threshold and greater than a soft exit voltage threshold.

Abstract: A circuit for Flyback switching power supply includes a transformer having a primary winding, a secondary winding and an auxiliary winding, a power switch coupled to a dotted terminal of the primary winding, and a switch. A first terminal of the switch is connected to a non-dotted terminal of the auxiliary winding through a capacitor, a second terminal of the switch and a dotted terminal of the auxiliary winding are connected, respectively, to a ground. A common node of the capacitor and the auxiliary winding is configured to connect to a non-dotted terminal of the primary winding. A control circuit is configured to generate, based on a voltage at the common node of the capacitor and the auxiliary winding, a control signal to control the switch in order to achieve zero voltage switch (ZVS) of the power switch.

Abstract: A display apparatus is provided. The display apparatus includes: a display panel, a non-volatile memory, and a controller. The controller is configured to adjust first gain values of the display panel, and obtain two-dimensional color coordinates in a first predetermined color space of the white screen displayed by the display apparatus as white-color coordinates. The controller further adjusts colors displayed by the display apparatus to fit a second predetermined color space, calculates second gain values in the second predetermined color space according to the white-color coordinates, and stores the second gain values in a color-calibration setting in a non-volatile memory of the display apparatus. In response to a selection signal from the display apparatus, the controller reads the color-calibration setting corresponding to the selection signal from the non-volatile memory for execution to perform color calibration on the display apparatus.

Abstract: A display apparatus is provided. The display apparatus includes: a display panel, a non-volatile memory, and a controller. The controller is configured to adjust first gain values of the display panel, and obtain two-dimensional color coordinates in a first predetermined color space of the white screen displayed by the display apparatus as white-color coordinates. The controller further adjusts colors displayed by the display apparatus to fit a second predetermined color space, calculates second gain values in the second predetermined color space according to the white-color coordinates, and stores the second gain values in a color-calibration setting in a non-volatile memory of the display apparatus. In response to a selection signal from the display apparatus, the controller reads the color-calibration setting corresponding to the selection signal from the non-volatile memory for execution to perform color calibration on the display apparatus.

Abstract: A discharging circuit for a power supply includes a rectifying circuit for coupling to an input filter capacitor coupled to an AC input voltage for providing a rectified AC voltage. A discharge resistor is coupled to the rectifying circuit, and a power switch and a discharging current source are coupled in series with the discharging resistor. A discharge control circuit is coupled to the discharge resistor for providing a discharge signal to cause the power switch to turn on for discharging the capacitor using the discharging current source. The discharging control circuit includes an AC voltage sampling circuit for providing a sampled rectified voltage, a signal-shaping circuit for providing a time-varying signal derived from the sampled rectified voltage, a comparator circuit for comparing the sampled rectified voltage and the time-varying signal, and a counter circuit for providing the discharge signal in response to an output of the comparator circuit.

Abstract: A discharging circuit for a power supply includes a rectifying circuit for coupling to an input filter capacitor coupled to an AC input voltage for providing a rectified AC voltage. A discharge resistor is coupled to the rectifying circuit, and a power switch and a discharging current source are coupled in series with the discharging resistor. A discharge control circuit is coupled to the discharge resistor for providing a discharge signal to cause the power switch to turn on for discharging the capacitor using the discharging current source. The discharging control circuit includes an AC voltage sampling circuit for providing a sampled rectified voltage, a signal-shaping circuit for providing a time-varying signal derived from the sampled rectified voltage, a comparator circuit for comparing the sampled rectified voltage and the time-varying signal, and a counter circuit for providing the discharge signal in response to an output of the comparator circuit.

Abstract: A method for programming extended display identification data (EDID) adapted to a display device is provided. The display device has at least one EDID chip, a microcontroller unit chip, and a flash memory chip. in the method, a first EDID corresponding to the EDID chip is written into a firmware stored in the flash memory chip. The display device is powered on. The first EDID in the firmware is automatically written into the corresponding EDID chip as a second EDID by the microcontroller unit chip.

Abstract: Method and apparatus for adding jitter to an oscillator for reducing EMI are disclosed An oscillator circuit includes an oscillator configured to generate a first clock having a first frequency and a frequency jitter circuit including a charge pump configured to charge and discharge first and second capacitors repeatedly for obtaining a time-varying voltage having a second frequency. The time-varying voltage is coupled to the oscillator to vary the first frequency within a frequency range. The charge pump includes a first switch for coupling the first capacitor to a voltage source and a second switch for coupling the first capacitor to the second capacitor. A charge transfer between the first and second capacitors is configured to provide the time-varying voltage.

Abstract: A controller for a switching mode power supply includes two semiconductor chips. The first semiconductor chip has a high-voltage startup transistor coupled to a high voltage supply input terminal and configured to provide a charging current in a startup phase or protection mode of a switching mode power supply (SMPS) and to provide substantially no current in a normal operation phase of the SMPS. The second semiconductor chip has a control circuit for controlling the switching mode power supply. The second semiconductor chip also has first and second on-chip high-voltage resistors coupled to the high-voltage supply input terminal and the high-voltage startup transistor in the first semiconductor chip. The first and the second on-chip high-voltage resistors are configured to provide a voltage and a current related to a voltage at the high-voltage supply input terminal.

Abstract: A controller for a switching mode power supply includes two semiconductor chips. The first semiconductor chip has a high-voltage startup transistor coupled to a high-voltage supply input terminal and configured to provide a charging current in a startup phase or protection mode of a switching mode power supply (SMPS) and to provide substantially no current in a normal operation phase of the SMPS. The second semiconductor chip has a control circuit for controlling the switching mode power supply. The second semiconductor chip also has first and second on-chip high-voltage resistors coupled to the high-voltage supply input terminal and the high-voltage startup transistor in the first semiconductor chip. The first and the second on-chip high-voltage resistors are configured to provide a voltage and a current related to a voltage at the high-voltage supply input terminal.

Abstract: Method and apparatus for adding jitter to an oscillator for reducing EMI are disclosed An oscillator circuit includes an oscillator configured to generate a first clock having a first frequency and a frequency jitter circuit including a charge pump configured to charge and discharge first and second capacitors repeatedly for obtaining a time-varying voltage having a second frequency. The time-varying voltage is coupled to the oscillator to vary the first frequency within a frequency range. The charge pump includes a first switch for coupling the first capacitor to a voltage source and a second switch for coupling the first capacitor to the second capacitor. A charge transfer between the first and second capacitors is configured to provide the time-varying voltage.

Abstract: A PWM controller has a line voltage input that allows using a start-up resistor for both start-up and power-limit compensations so that it can save the power consumption, ease the PCB layout, and shrink the power supply size. In the integrated circuit, a current switch used for both start-up and line voltage sensing is composed of a diode and a switch transistor. A current multiplier is used to improve the precise by canceling the impact of the integrated resistor's absolute value, which is composed of a transistor loop, a constant current and a reference current. Thus, by properly selecting the value of the start-up resistor, an identical output power limit for low line and high line voltage input can be achieved.