A5941 is a sensorless three-phase motor driver chip for medium-power fan applications. This chip integrates sine wave signal output drive, so it can minimize the operating noise and vibration of the fan. During startup, a sine wave voltage signal is output to the motor coil, which starts slowly and gradually accelerates the motor to the required speed, thus realizing the so-called soft start. The default output voltage can drive the motor to work in a wide range of characteristics.

    In addition, the A5941 chip is also integrated with an EEPROM memory unit (see the next issue for details). According to the application needs, you can customize the start of the motor by changing the configuration instructions stored in the EEPROM. The speed regulation of the motor is realized by controlling the duty cycle of the PWM input signal, and the allowable frequency range of the PWM signal is very wide. According to requirements, EEPROM can also be configured to adjust the motor speed through analog voltage input. A5941 chip can detect the rotor position of three-phase motor without external Hall sensor. The advantages of this technology can not only eliminate the maintenance problems caused by the damage of the Hall sensor, improve the reliability of the fan motor, expand the application range, and reduce the production cost, but also eliminate the detection error caused by the sensor inconsistency. The A5941 chip adopts a 10-pin SOIC package.

    The A5941 three-phase motor driver integrates the sine signal drive function to minimize the audible noise and vibration of the medium power fan.

    180 ° sine signal drive - low audible noise and vibration

    The motor position is obtained according to Allegro‘s sensorless algorithm without external Hall sensor