Abstract: The present invention relates to a charge status indicator and a charger. The charger comprises a charging power supply and a charge status indicator, wherein, the charge status indicator comprises a detecting chip for monitoring charge status connected between the primary winding of transformer and ground, and a display module used for displaying the charge status, wherein, said detecting chip for monitoring charge status comprising: a detecting module for detecting the charging state of the charge power supply; a comparing module for determining the current charge status based on the detected charging state. By employing the charger or the charge status indicator for a charger, a primary-side feedback control Flyback SMPS may be employed, just a simple and reliable circuit is needed, and higher efficient can be achieved.

Abstract: The present invention relates to a frequency jittering device and method, and a switching power supply employing such frequency jittering device. Said method comprises: S1 generating a variable logic number; S2 generating a delay signal; S3 generating a PWM control signal according to the variable logic number and the delay signal; S4 generating an output signal according to the PWM control signal; and S5 generating a clock signal with variable frequency according to the output signal; wherein, the clock signal is fed back to update the variable logic number, and a jittering clock signal modified in each clock cycle is produced. The benefit of the present invention is not only can apply small low cost EMI filter but also can keep the noise floor level low enough at light load condition.

Abstract: A controller for reducing the harmonics contents in the AC-to-DC converter that is capable of minimizing THD due to crossover distortion. The controller can approximate the shape of the current running through boost inductor to the sinusoidal waveform of the rectified line input voltage and in the meantime to keep the valley of rectified sinusoidal waveform line voltage close to local ground value. The controller can be used in a transition mode power factor correction device suitable for a wide range of AC line input voltage and output loading application.

Abstract: The present invention relates to clamp protection circuit and a PFC control circuit employing such clamp protection circuit. Said clamp protection circuit comprises a high voltage isolation module used for receiving power from a high voltage power supply; a voltage clamp module used for receiving an output low voltage from the high voltage isolation module and realizing a clamp protection; and a low voltage bias module used for providing bias voltage to the high voltage isolation module and the voltage clamp module. By employing the clamp protection circuit, the precision of the clamp voltage is improved, the design is simplified and the silicon area is reduced. Meanwhile, the transient response is enhanced.

Abstract: The present invention relates to a charge status indicator and a charger. The charger comprises a charging power supply and a charge status indicator, wherein, the charge status indicator comprises a detecting chip for monitoring charge status connected between the primary winding of transformer and ground, and a display module used for displaying the charge status, wherein, said detecting chip for monitoring charge status comprising: a detecting module for detecting the charging state of the charge power supply; a comparing module for determining the current charge status based on the detected charging state. By employing the charger or the charge status indicator for a charger, a primary-side feedback control Flyback SMPS may be employed, just a simple and reliable circuit is needed, and higher efficient can be achieved.

Abstract: The present invention relates to a frequency jittering device and method, and a switching power supply employing such frequency jittering device. Said method comprises: S1 generating a variable logic number; S2 generating a delay signal; S3 generating a PWM control signal according to the variable logic number and the delay signal; S4 generating an output signal according to the PWM control signal; and S5 generating a clock signal with variable frequency according to the output signal; wherein, the clock signal is fed back to update the variable logic number, and a jittering clock signal modified in each clock cycle is produced. The benefit of the present invention is not only can apply small low cost EMI filter but also can keep the noise floor level low enough at light load condition.

Abstract: The present invention relates to clamp protection circuit and a PFC control circuit employing such clamp protection circuit. Said clamp protection circuit comprises a high voltage isolation module used for receiving power from a high voltage power supply; a voltage clamp module used for receiving an output low voltage from the high voltage isolation module and realizing a clamp protection; and a low voltage bias module used for providing bias voltage to the high voltage isolation module and the voltage clamp module. By employing the clamp protection circuit, the precision of the clamp voltage is improved, the design is simplified and the silicon area is reduced. Meanwhile, the transient response is enhanced.

Abstract: The present invention relates to controller for reducing the harmonics contents in the AC-to-DC converter.