Abstract: A power converter having a mechanism of dynamically controlling a minimum off time is provided. A high-side overcurrent protecting circuit determines whether or not a current flows from a high-side switch through a node between a second terminal of the high-side switch and a first terminal of a low-side switch toward an inductor, and determines whether or not the current is larger than a threshold to output a high-side overcurrent detected signal and a high-side overcurrent protecting signal. An off time adjusting circuit outputs a minimum off time signal to a driver circuit according to the high-side overcurrent protecting signal. The driver circuit determines that an overcurrent event occurs when the high-side switch is turned on according to the high-side overcurrent detected signal, and accordingly the driver circuit at least continually turns on the low-side switch during a longer minimum off time of the minimum off time signal.

Abstract: A sensor is provided. A first terminal of a first current source and a first terminal of a first transistor are connected to a cathode of the photodiode. A control terminal of a second transistor is connected to an output terminal of a first operational amplifier. A first terminal of the second transistor is connected to a second terminal of the first transistor through a first current mirror circuit. A second terminal of the second transistor is connected to a second current source, a second input terminal of a second operational amplifier and a first terminal of a third transistor. A first input terminal of the second operational amplifier is connected to the first terminal of the first transistor. A control terminal of the third transistor is connected to an output terminal of the second operational amplifier.

Abstract: A motor current protecting circuit is provided. A voltage calculating circuit determines whether or not each of low-side switches is fully turned on and then determines whether or not a voltage difference between a first terminal and a second terminal of each of the low-side switches being fully turned on is larger than or equal to a zero value. The voltage calculating circuit adds up the voltage differences each of which is larger than or equal to the zero value to output a voltage signal. A control circuit controls a driver circuit to switch the low-side switches and high-side switches according to the voltage signal.

Abstract: A motor controller circuit having a rotational speed locking mechanism is provided. Each time when a motor commutates, a first signal generating circuit resets a first waveform signal and a second signal generating circuit resets a second waveform signal. An output signal generating circuit outputs a waveform output signal according to the first waveform signal and the second waveform signal. A motor controller circuit outputs an on-time signal according to the waveform output signal. A motor driving circuit outputs a driving signal to the motor to drive the motor to rotate according to the on-time signal.

Abstract: A closed-loop inductor current emulating circuit is provided. An emulation controller circuit generates an emulating signal according to a current flowing through a first terminal of a low-side switch of a power converter. When the emulation controller circuit outputs the emulating signal to a charging and discharging circuit, the charging and discharging circuit outputs a charging and discharging signal to a first terminal of a capacitor according to the emulating signal. When the emulation controller circuit outputs the emulating signal to a control terminal of the capacitor to adjust a capacitance of the capacitor, the charging and discharging circuit outputs a charging and discharging signal to the first terminal of the capacitor according to one or both of an input voltage and an output voltage of the power converter.

Abstract: A motor driver having an automatic phase switching mechanism is provided. After a three-phase motor is started up, a back electromotive force detecting circuit starts detecting a back electromotive force signal of each of three phases of the three-phase motor. A driving waveform generating circuit extracts parts of a plurality of first wave segment patterns from a first wave segment pattern signal as a plurality of first wave segments of a first waveform signal according to the back electromotive force signal. A motor controlling circuit controls the motor driving circuit to drive the three-phase motor to rotate normally according to the first waveform signal.

Abstract: A power managing system and method are provided. When an under voltage lockout circuit determines that a common voltage of the power managing system is lower than a first lockout voltage, the under voltage lockout circuit outputs a first under voltage lockout signal for controlling one of a plurality of power converters that supplies a highest output voltage to rapidly reduce its output voltage to a zero value. Then, the under voltage lockout circuit outputs a second under voltage lockout signal for controlling another one of the power converters that supplies a lowest output voltage to gradually reduce its output voltage to the zero value.

Abstract: An overvoltage protecting system and method of a motor pre-driver are provided. An overvoltage protecting circuit compares a first reference voltage with a common voltage inputted to a single phase motor to output a first comparison signal. When a controller circuit determines that the common voltage is higher than the first reference voltage according to the first comparison signal, the controller circuit turns off a first high-side switch and a second high-side switch, and turns on the first low-side switch and the second low-side switch, during a phase time of a phase transition signal of the single phase motor. After the phase time ends, the controller circuit alternately turns on the first low-side switch and the second low-side switch according to a level of the phase transition signal.

Abstract: A multiphase power converter having a daisy chain control circuit and a method for controlling the same are provided. A main control circuit outputs an initial pulse width modulation signal having a plurality of initial pulses. One of a plurality of slave control circuits is connected to an output terminal of the main control circuit, and outputs a pulse width modulation signal according to the received initial pulse width modulation signal. Each of the rest of the plurality of slave control circuits outputs the next pulse width modulation signal to the next slave control circuit or the main control circuit according to the pulse width modulation signal received from the previous slave control circuit. The main control circuit automatically counts a quantity of the control circuits according to the received pulse width modulation signal and outputted initial pulse width modulation signal.

Abstract: A rotation locking system of a motor of a fan is provided. A closed-loop control circuit outputs an initial duty cycle signal according to a current rotational speed and a target rotational speed. A driver circuit outputs a driving signal to the motor to drive the motor to rotate according to the initial duty cycle signal. A lookup table arithmetic circuit looks up, from a lookup table, two reference duty cycles correspond to two reference rotational speeds that are respectively equal to the current rotational speed and the target rotational speed. The lookup table arithmetic circuit calculates a difference between the two reference duty cycles. A speed feedback control circuit compensates the initial duty cycle signal according to the difference to output a final duty cycle signal to the driver circuit. The driver circuit drives the motor to rotate according to the final duty cycle signal.

Abstract: A power saving system of a battery charger is provided. A control terminal of a first transistor receives a wake-up signal. A counter is connected to a first terminal of the first transistor. The counter determines whether or not a working period of the wake-up signal from the first transistor is larger than a time threshold to output a counting signal. When the counting signal indicates that the working period of the wake-up signal is not larger than the time threshold, the counter and electronic components of an electronic device are turned off, thereby saving power of a battery. When the counting signal indicates that the working period of the wake-up signal is larger than the time threshold, the electronic device is switched from a power saving mode to a normal operation mode. In the normal operation mode, the battery can supply power to the electronic device.

Abstract: A motor controller circuit having a stable speed controlling mechanism is provided. A duty cycle determining circuit determines duty cycles of the plurality of waveforms respectively of the first waveform signals within each of a plurality of time intervals to output a duty cycle instructing signal, according to a target working period corresponding to a target rotational speed. A signal generating circuit outputs the plurality of first waveform signals according to the duty cycle instructing signal, and outputs a second waveform signal. A motor control circuit outputs a plurality of on-time signals according to the plurality of first waveform signals and the second waveform signal. A motor driving circuit is controlled to operate and drive a motor to rotate according to the plurality of on-time signals.

Abstract: A light sensor having a control complexity reducing mechanism is provided. When light is emitted to a photodiode by both of an ambient light source and a light-emitting component, a first coarse count value is counted by a counter and then is sampled and held by a first sample and hold circuit. When light is emitted to the photodiode by only the ambient light source, a second coarse count value is counted by the counter and then is sampled and held by a second sample and hold circuit. After the coarse count values are held, the counter performs a fine counting operation on light intensity of the light emitted by both of the ambient light source and the light-emitting component to generate a first fine count value, and on light intensity of the light emitted by only the ambient light source to generate a second fine count value.

Abstract: A brake control system of a motor is provided. When a control circuit intends to brake the motor, the control circuit controls a driver circuit to turn off a first high-side switch and a second high-side switch, and to fully turn on the first low-side switch and the second low-side switch, for a period of time. Then, the control circuit controls the driver circuit to turn off one of the first low-side switch and the second low-side switch, and to continually turn on the other one of the first low-side switch and the second low-side switch, for a period of time. Then, the control circuit controls the driver circuit to turn off the other one of the first low-side switch and the second low-side switch, and to turn on the one of the first low-side switch and the second low-side switch, for a period of time.

Abstract: A power converter for providing a negative voltage is provided. A coupling controller circuit receives a digital control signal and provides a control signal. A reverse voltage converter circuit receives the control signal and provides a reverse voltage. The reverse voltage converter circuit includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a seventh switch, an eighth switch, a coupling control signal triggering circuit and a pulse width modulation circuit. A first reverse logic circuit is connected to a second reverse logic circuit. The second reverse logic circuit is connected to the pulse width modulation circuit and is configured to provide a trigger signal to the pulse width modulation circuit. The pulse width modulation circuit turns on or off the reverse voltage converter circuit according to the trigger signal.

Abstract: A power converter having a slew rate controlling mechanism is provided. A first terminal of a high-side switch is coupled to an input voltage. A first terminal of a low-side switch is connected to a second terminal of the high-side switch. A second terminal of a first capacitor is connected to a node between the second terminal of the high-side switch and the first terminal of the low-side switch. A first terminal of an inductor is connected to the second terminal of the first capacitor and to the node. A first terminal of a second capacitor is connected to a second terminal of the inductor. A second terminal of the second capacitor is grounded. An input terminal of a current controlling device is connected to a power output terminal of a high-side buffer. An output terminal of the current controlling device is connected to the node.

Abstract: A current limit protecting system and method of a motor pre-driver are provided. A current limiting circuit detects a current of a resistor that is connected to a motor, and then compares the current of the resistor with a current threshold to output a current comparing signal. When a controller circuit determines that the current of the resistor is larger than the current threshold according to the current comparing signal, and a working period of a first signal of a first node or a working period of a second signal of a second node of the motor reaches a preset value, a first high-side switch and a second high-side switch are turned off, and a first low-side switch and a second low-side switch are alternately turned on. As a result, a temperature of the motor generally reduces.

Abstract: A sensor is provided. A first terminal of a first current source and a first terminal of a first transistor are connected to a cathode of the photodiode. A control terminal of a second transistor is connected to an output terminal of a first operational amplifier. A first terminal of the second transistor is connected to a second terminal of the first transistor through a first current mirror circuit. A second terminal of the second transistor is connected to a second current source, a second input terminal of a second operational amplifier and a first terminal of a third transistor. A first input terminal of the second operational amplifier is connected to the first terminal of the first transistor. A control terminal of the third transistor is connected to an output terminal of the second operational amplifier.

Abstract: A system and a method for automatically correcting a rotational speed of a motor of a fan are provided. After the fan is moved from an open space to a closed space, a sample and hold circuit samples and holds working periods of a driving signal by which the motor is driven to rotate at a first rotational speed as a first sampled working period, and a working period of a driving signal by which the motor is driven to rotate at a second rotational speed. An arithmetic circuit calculates a difference between the first sampled working period and a first reference working period, and a difference between the second sampled working period and a second reference working period. The arithmetic circuit calculates other working periods of driving signals by which the motor is driven to rotate at other rotational speeds based on the differences.

Abstract: A rapid sensing value estimation circuit and a method thereof are provided. The circuit includes a first sensing unit, an integration sensing circuit and a rapid estimation circuit. The rapid estimation circuit includes a clock generator, a second counter, a first digital comparator, an arithmetic module and a remainder calculation module. The clock generator generates a clock signal with a first frequency. The second counter counts the clock signal within the integration time to generate a second count value. The first digital comparator determines whether the second count value exceeds a first predetermined count value when the first count value increases. The arithmetic module calculates an estimated count value result and a remainder, and the remainder calculation module can further calculate and estimate values of decimal places of this signal based on the remainder.