A3977SED Application Field and Working Principle

The A3977SE is a three phase brushless dc (BLDC) motor controller and driver. It is designed to drive a BLDC motor withHall sensors, usually through pulse width modulation (PWM) of the outputs.

The A3977SE contains an insertable power stage featuring three integrated N-channel power MOSFETs that can deliver4A of continuous output current per phase; an internal charge pump for gate drive; comparator, independent dead-timegeneration; and pulse-by-pulse current limiting as protection features. It also contains a three-phase derating descentinverse Park transform and a synchronous rectifier for improved efficiency.

Application Field

The A3977SE device is ideal for the small size BLDC motors used in many applications like Haier home appliances， suchlike air-conditioners, refrigerators, and inverter motors. It is also used in industrial applications suchlike drones, 3D printers etc.

Working Principle

The A3977SE drives a BLDC motor using sinusoidal commutation with Hall sensors and/or zero crossing detection.The A3977SE starts up in a “6-step mode” and once in operation, adapts off-time modulation based on the load of the motor toachieve the best efficiency for the motor. When leaving the 6-step mode, the A3977SE device transitions to sinusoidal modebased on a simple algorithm.

The A3977SE offers true sinusoidal control of PMSM motors with current and voltage drive capabilities; Operation in Voltagemode, as well as current mode, enables highest speed performance, as well as temperature stability and acousticmeasurement.The A3977SE is also capable of detecting a stall condition and entering a low power ride-modes to monitor thetemperature of motor

In addition, the A3977SE utilizes internal dead-time, pulse-by-pulse current limiting, and pulse-by-pulse full-bridgeshort-circuit protection, which help to provide protection against driving excessive currents and maintaining the A3977SEdevice under temperature stability.