Abstract: A multiphase motor driving circuit includes: a power stage circuit; and a control circuit. In a motor braking mode, when a holding voltage is less than the first voltage threshold, a first sub-mode is entered, in which the control circuit controls at least a portion of switches in the power stage circuit with a pulse width modulation (PWM) signal to switch periodically, thereby converting a back electromotive force (EMF) of a multiphase motor into the holding voltage to supply power to the control circuit. In the motor braking mode, when the holding voltage is greater than the second voltage threshold, a second sub-mode is entered, in which the control circuit controls at least a portion of switches in the power stage circuit with the PWM signal to keep them continuously conductive, thereby consuming the back EMF of the multiphase motor to reduce a speed of the multiphase motor.

Abstract: A method for predicting failure of a cooling fan includes driving a motor of the cooling fan based on a control speed, generating a first speed according to an average speed of the motor, generating a first current according to an average current of the motor, retrieving a system coefficient from a memory, generating a current threshold according to the first speed and the system coefficient, and triggering an alarm signal if the first current exceeds the current threshold by a threshold amount.

Abstract: A BLDC motor driver circuit includes: a driving power stage circuit configured to provide a start-up test signal in a start-up mode to excite a BLDC motor, to drive a rotor of the BLDC motor to rotate for a test; a current unidirectional circuit coupled to the BLDC motor at a reverse end for detecting a BEMF, to generate a detection signal at a forward end of the current unidirectional circuit, wherein when a voltage at the reverse end exceeds a voltage at the forward end, the current unidirectional circuit limits the voltage at the forward end not to be higher than a clamp voltage; a biasing circuit for biasing the current unidirectional circuit in a forward operation state and for providing the clamp voltage; and a sensor circuit for generating a sensing signal according to the detection signal to indicate a test rotation state of the BLDC motor.

Abstract: A BLDC motor driver circuit includes: a driving power stage circuit configured to provide a start-up test signal in a start-up mode to excite a BLDC motor, to drive a rotor of the BLDC motor to rotate for a test; a current unidirectional circuit coupled to the BLDC motor at a reverse end for detecting a BEMF, to generate a detection signal at a forward end of the current unidirectional circuit, wherein when a voltage at the reverse end exceeds a voltage at the forward end, the current unidirectional circuit limits the voltage at the forward end not to be higher than a clamp voltage; a biasing circuit for biasing the current unidirectional circuit in a forward operation state and for providing the clamp voltage; and a sensor circuit for generating a sensing signal according to the detection signal to indicate a test rotation state of the BLDC motor.

Abstract: A gain controlling system, a sound playback system, and a gain controlling method thereof are disclosed. The gain controlling system includes a main gain control unit, a sub gain control unit, and a logic control unit. The main gain control unit has a first step-by-step adjusting magnitude; the sub gain control unit has a second step-by-step adjusting magnitude; wherein the second step-by-step adjusting magnitude is smaller than the first step-by-step adjusting magnitude. The logic control unit is used for controlling the main and the sub gain control unit to transform an analog signal into a converted signal according to an adjustment command signal and further determining whether an adjusting magnitude required by the adjustment command signal is larger than a maximum gain range of the sub gain control unit. If yes, the logic control unit controls the main control unit and the sub gain control unit repeatedly.

Abstract: A gain controlling system, a sound playback system, and a gain controlling method thereof are disclosed. The gain controlling system includes a main gain control unit, a sub gain control unit, and a logic control unit. The main gain control unit has a first step-by-step adjusting magnitude; the sub gain control unit has a second step-by-step adjusting magnitude; wherein the second step-by-step adjusting magnitude is smaller than the first step-by-step adjusting magnitude. The logic control unit is used for controlling the main and the sub gain control unit to transform an analog signal into a converted signal according to an adjustment command signal and further determining whether an adjusting magnitude required by the adjustment command signal is larger than a maximum gain range of the sub gain control unit. If yes, the logic control unit controls the main control unit and the sub gain control unit repeatedly.