Abstract: The present invention discloses a safety capacitor discharging method for AC-to-DC converters, wherein the AC-to-DC converters have a safety capacitor connected between two line voltages, the method comprising the steps of: detecting at least one line voltage to generate a line-off signal, wherein the line-off signal is at a first state when the peak voltage of the at least one line voltage is above a reference voltage, and the line-off signal is at a second state when the peak voltage of the at least one line voltage is below the reference voltage; and performing discharge of the safety capacitor by generating a conduction path between two plates of the safety capacitor when the line-off signal is at the second state. The present invention also provides a safety capacitor discharging apparatus for AC-to-DC converters.

Abstract: A low-pin count fan speed control system and a method thereof include primarily an activation unit to drive a fan to operate. When the fan starts completely, the fan slows down to a pre-determined rotation speed through an idle speed regulation unit. After achieving a pre-determined temperature through a temperature transition unit, the fan speed beings to increase from the idle speed. When the fan is operating, the rotation speed is properly increased in proportion to the temperature, using a positive temperature regulation slope unit. Therefore, through this method, the rotation speed will not be decreased by foreign objects when the fan is operating and a computer host can be provided with proper heat dissipation.

Abstract: The present invention discloses a single chip ballast controller, capable of providing brightness levels overview and brightness setting of a fluorescent lamp during power-on period, having: a switching detection circuit, used to generate a set signal, which changes from an inactive state to an active state when a supply voltage falls below a threshold voltage; a time-varying reference voltage generator, used to generate a time-varying reference voltage varying between a first level and a second level during a power-on period, wherein the time-varying reference voltage can be fixed at a level by the active state of the set signal during the power-on period; and a gating signal generator, used to generate a high side driving signal and a low side driving signal according to an error voltage between the time-varying reference voltage and a current sensing voltage.

Abstract: The present invention relates a single chip ballast controller for step-dimming of a fluorescent lamp, comprising: a counting circuit, used to generate a switching count by counting the instances where the supply voltage falls below a threshold voltage; a reference voltage generator, used to generate a reference voltage proportional to the switching count; and a gating signal generator, used to generate a high side driving signal and a low side driving signal according to an error voltage between the reference voltage and a current sensing voltage to regulate the current sensing voltage at the reference voltage, wherein the current sensing voltage is proportional to a lamp current flowing through the fluorescent lamp.

Abstract: A single-pin multifunctional device and method for input and output in controlling a direct-current fan use a control chip to control an operation of the fan, thereby protecting issues generated by too high a temperature. The control chip uses a value of a temperature induction unit to determine a range of protection and maintains the fan at an idle speed operation through an idle speed regulation unit. Meanwhile, the temperature induction unit notifies an over-temperature protection unit to switch from the idle speed regulation unit to the over-temperature protection unit. Therefore, the fan is controlled through a single pin to input and output simultaneously.

Abstract: The present invention discloses a safety capacitor discharging method for AC-to-DC converters, wherein the AC-to-DC converters have a safety capacitor connected between two line voltages, the method comprising the steps of: detecting at least one line voltage to generate a line-off signal, wherein the line-off signal is at a first state when the peak voltage of the at least one line voltage is above a reference voltage, and the line-off signal is at a second state when the peak voltage of the at least one line voltage is below the reference voltage; and performing discharge of the safety capacitor by generating a conduction path between two plates of the safety capacitor when the line-off signal is at the second state. The present invention also provides a safety capacitor discharging apparatus for AC-to-DC converters.

Abstract: The present invention discloses a standby power reduction method and apparatus for switching power applications, the method comprising the steps of: performing a hysteresis comparison on a supply voltage to generate a selecting signal having a first state and a second state, wherein the hysteresis comparison has a high threshold voltage compared to the supply voltage when the selecting signal is at the first state, and the hysteresis comparison has a low threshold voltage compared to the supply voltage when the selecting signal is at the second state; and determining a UVLO_ON voltage according to the selecting signal, wherein the UVLO_ON voltage is equal to a first level when the selecting signal is at the first state, and the UVLO_ON voltage is equal to a second level when the selecting signal is at the second state.

Abstract: The present invention discloses a control circuit for a variable frequency DC motor, the control circuit comprising: a controller, having a voltage sensing input end and a control output end, wherein the control output end is used to deliver an output signal according to the difference between a threshold voltage and the voltage at the voltage sensing input end; a transistor, having a first terminal, a second terminal and a third terminal, wherein the first terminal is coupled to the voltage sensing input end, and the second terminal is coupled to the variable frequency DC motor, and the third terminal is coupled to a reference ground; and a voltage divider, coupled between the second terminal and the third terminal, used to generate a feedback voltage for the voltage sensing input end; wherein the voltage at the second terminal is regulated according to the threshold voltage.

Abstract: A low-pin count fan speed control system and a method thereof include primarily an activation unit to drive a fan to operate. When the fan starts completely, the fan slows down to a pre-determined rotation speed through an idle speed regulation unit. After achieving a pre-determined temperature through a temperature transition unit, the fan speed beings to increase from the idle speed. When the fan is operating, the rotation speed is properly increased in proportion to the temperature, using a positive temperature regulation slope unit. Therefore, through this method, the rotation speed will not be decreased by foreign objects when the fan is operating and a computer host can be provided with proper heat dissipation.

Abstract: The present invention discloses a standby power saving method for power module applications, comprising the steps of: generating a mode signal according to voltage comparison of a feedback signal and a threshold voltage, wherein the mode signal has a normal mode state and a standby mode state; generating a pulse signal according to the mode signal, wherein the pulse signal has a normal PWM mode responsive to the normal mode state of the mode signal, and a VCC mode responsive to the standby mode state of the mode signal; and generating a gating signal according to the pulse signal for driving a primary side power switch. The present invention also provides a standby power saving apparatus for power module applications.