Abstract: A jittering frequency control circuit and method for a switching mode power supply enlarge the uttering frequency range of the switching frequency of the switching mode power supply when the switching mode power supplier enters a frequency reduction mode, to improve the electro-magnetic interference of the switching mode power supply operating with the frequency reduction mode.

Abstract: A state cycling apparatus uses a capacitor instead of complicated and expensive microcontroller to fulfill a state cycling function of a system. The state cycling apparatus includes an internal circuit in the system connected to the capacitor. In a first embodiment, the internal circuit reads the voltage level on the capacitor at power on to determine a current state for the system, and writes the voltage level corresponding to a next state of the system to the capacitor. In a second embodiment, the system reads the state data stored in the internal circuit to determine a current state for the system at power on, the capacitor is charged during the system is under power on, and the capacitor provides power for the internal circuit to store a state data after the system is powered off.

Abstract: A state cycling apparatus uses a capacitor instead of complicated and expensive microcontroller to fulfill a state cycling function of a system. The state cycling apparatus includes an internal circuit in the system connected to the capacitor. In a first embodiment, the internal circuit reads the voltage level on the capacitor at power on to determine a current state for the system, and writes the voltage level corresponding to a next state of the system to the capacitor. In a second embodiment, the system reads the state data stored in the internal circuit to determine a current state for the system at power on, the capacitor is charged during the system is under power on, and the capacitor provides power for the internal circuit to store a state data after the system is powered off.

Abstract: A dimming circuit and method for a LED provide a first driving voltage or a second driving voltage according to a dimming signal provided by a functional IC to enable or disable the LED. The values of the first and second driving voltages are controlled so that overstressing of the LED is avoided while the functional IC is capable of working even when the LED is off. The LED's life time is thus prolonged.

Abstract: An apparatus and method for a flyback power converter reduce the standby output voltage of the flyback power converter by switching the reference voltage provided by a shunt regulator of the flyback power converter or the ratio of voltage divider resistors of the shunt regulator, to reduce the standby power consumption by an output feedback circuit of the flyback power converter, the shunt regulator, and the voltage divider resistors, and thereby improve the power loss of the flyback power converter in standby mode.

Abstract: A state cycling apparatus uses a capacitor instead of complicated and expensive microcontroller to fulfill a state cycling function of a system. The state cycling apparatus includes an internal circuit in the system connected to the capacitor. In a first embodiment, the internal circuit reads the voltage level on the capacitor at power on to determine a current state for the system, and writes the voltage level corresponding to a next state of the system to the capacitor. In a second embodiment, the system reads the state data stored in the internal circuit to determine a current state for the system at power on, the capacitor is charged during the system is under power on, and the capacitor provides power for the internal circuit to store a state data after the system is powered off.

Abstract: The present invention discloses a power supply input voltage detection circuit. The power supply converts an input voltage to an output voltage by a transformer which includes a primary winding and a secondary winding. The primary winding is coupled to a power switch, which receives a switching signal to adjust the output voltage. The power switch is coupled to a sensing circuit; when the power switch turns ON, the sensing circuit generates a current sense signal according to current through the primary winding. The input voltage detection circuit includes: a rising time detection circuit, which detects a period, of time during which the current sense signal rises from a low reference level to a high reference level to generate a timing signal; and a determination circuit, which generates a determination signal according to the timing signal for determining whether the input signal is a high voltage or a low voltage.

Abstract: A circuit and method are provided for a power converter to select one from a plurality of current limit signals as a final current limit signal according to the present duty ratio of a power switch for the pulse width modulation of the next cycle, so that the duty ratio of the power switch in the next cycle is prevented from acute variation to eliminate sub-harmonic which otherwise may happen.

Abstract: A pulse width modulation controller and method for output ripple reduction of a jittering frequency switching power supply detect the current of a power switch of the switching power supply to generate a current sense signal, and adjust the gain or the level of the current sense signal according to the switching frequency of the power switch to adjust the on time of the power switch, to reduce the output ripple of the switching power supply caused by the jittering frequency of the switching power supply.

Abstract: A dimming circuit and method for a LED provide a first driving voltage or a second driving voltage according to a dimming signal provided by a functional IC to enable or disable the LED. The values of the first and second driving voltages are controlled so that overstressing of the LED is avoided while the functional IC is capable of working even when the LED is off. The LED's life time is thus prolonged.

Abstract: The present invention discloses a power stage control circuit including: a driver circuit for controlling a power stage according to an error amplified signal; an error amplifier circuit for comparing a feedback voltage at a feedback terminal with a reference signal to generate the error amplified signal; a current generator circuit coupled to the feedback terminal for generating a fault detection current flowing to the feedback terminal; and a feedback terminal short detection circuit for generating a fault signal to stop the operation of the power stage when the feedback voltage is smaller than a short-circuit threshold voltage or when the fault detection current is larger than a short-circuit threshold current.

Abstract: A switch embedded integrated circuit for battery protection includes a first pin to be connected with one terminal of a battery, a second pin to be connected with a load or charger, a third pin to be connected with another terminal of the battery, a MOSFET having a body diode thereof and connected between the first and second pins, a control logic circuit and a detection circuit. The detection circuit monitors the voltage between the first pin and the third pin to determine a detection signal for the control logic circuit to turn on or off the MOSFET and switch the direction of the body diode, thereby providing an over charging and an over discharging protection functions.

Abstract: A display includes a power supply system using a power controller to switch a power switch to control power delivery, and an image scalar receiving a supply voltage and a supply current from the power supply system. An apparatus and method are proposed to determine a control signal in a standby mode by monitoring the supply voltage or the supply current, to wake up or turn off the power controller to reduce the switching times of the power switch in the standby mode, thereby reducing the switching loss of the power switch and the standby power consumption of the display.

Abstract: A voltage detector includes a zener diode having a cathode connected to a detect terminal of the voltage detector, a junction field effect transistor having an input terminal connected to an anode of the zener diode, and a resistor connected between an output terminal and a control terminal of the junction field effect transistor. When the voltage on the detect terminal is higher than the breakdown voltage of the zener diode, the junction field effect transistor produces a current flowing through the resistor, and thereby a detection signal can be obtained from the voltage across the resistor.

Abstract: A dimming circuit and method for a LED provide a first driving voltage or a second driving voltage according to a dimming signal provided by a functional IC to enable or disable the LED. The values of the first and second driving voltages are controlled so that overstressing of the LED is avoided while the functional IC is capable of working even when the LED is off. The LED's life time is thus prolonged.

Abstract: A control circuit and method for a LED driver accurately control the output current of the LED driver by adjusting a reference voltage or a feedback voltage according to the input voltage of the LED driver such that the output current decreases with the decrease of the input voltage. Therefore, it enhances the efficiency of the LED driver and maximizes the battery use time of a battery powered system.

Abstract: An isolated type power supply includes a transformer, and a power switch and a current sense resistor serially connected to a primary coil of the transformer, and a protection apparatus and method monitor a control signal which is used to switch the power switch in normal operation, and trigger a signal to stop the power from switching when the control signal becomes greater than a threshold. This protection apparatus and method can more quickly detect short circuit of the current sense resistor, and prevent the isolated type power supply from overcurrent impact.

Abstract: A state cycling apparatus uses a capacitor instead of complicated and expensive microcontroller to fulfill a state cycling function of a system. The state cycling apparatus includes an internal circuit in the system connected to the capacitor. In a first embodiment, the internal circuit reads the voltage level on the capacitor at power on to determine a current state for the system, and writes the voltage level corresponding to a next state of the system to the capacitor. In a second embodiment, the system reads the state data stored in the internal circuit to determine a current state for the system at power on, the capacitor is charged during the system is under power on, and the capacitor provides power for the internal circuit to store a state data after the system is powered off.

Abstract: A state cycling apparatus uses a capacitor instead of complicated and expensive microcontroller to fulfill a state cycling function of a system. The state cycling apparatus includes an internal circuit in the system connected to the capacitor. In a first embodiment, the internal circuit reads the voltage level on the capacitor at power on to determine a current state for the system, and writes the voltage level corresponding to a next state of the system to the capacitor. In a second embodiment, the system reads the state data stored in the internal circuit to determine a current state for the system at power on, the capacitor is charged during the system is under power on, and the capacitor provides power for the internal circuit to store a state data after the system is powered off.

Abstract: Disclosed are methods of detection for output short circuit of a flyback power supply, which detect the current sense signal provided by a current sense resistor serially connected to a power switch of the flyback power supply, and thus quickly identify whether or not the flyback power supply suffers output short circuit.