A4936: 3-Phase Brushless DC Motor Pre-Driver


This device is no longer in production. The device should not be purchased for new design applications. Samples are no longer available. Date of status change: March 6, 2017

The A4936 is a complete 3-phase brushless DC motor pre-driver, supplying up to 28 V output for direct, high-current gate drive of an all N-channel power MOSFET 3-phase bridge. The device has three Hall-element inputs, a sequencer for commutation control, fixed off-time pulse width modulation (PWM) current control, and locked-rotor detection.

Output current is scaled by the capability of the external MOSFETs. Locked rotor detection delay is set by an external capacitor on the CLD terminal. The PWM, DIR, and BRAKE and STOP inputs can be used to control motor speed, position, and torque. Motor speed can be determined using the FG output from an FG coil amplifier and comparator.

The external MOSFETS can be PWMed using an external signal on the PWM input, or using the internal PWM current regulator. In either case, the A4936 synchronous rectification feature reduces power dissipation by turning-on the appropriate MOSFETs during current decay.

The Hall elements can be inexpensive types, when used with noise filtering to prevent false commutation signals. The A4936 provides a regulated 7.5 V supply to power the three Hall elements.

Internal circuit protection includes thermal shutdown with hysteresis, undervoltage lockout, and dead time protection. Special power-up sequencing is not required. Operating temperature range is –20°C to 105°C.

Top Features

  • Drives 6 N-channel MOSFETs
  • Synchronous rectification for low power dissipation
  • Internal UVLO and thermal shutdown circuitry
  • Hall element inputs
  • PWM current limiting
  • Dead time protection
  • FG outputs
  • Standby mode
  • Lock detect protection
  • Overvoltage protection

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
A4936MET-T 32-lead QFN -20°C to 105°C Yes View Data Discontinued Contact your
local sales rep
Distributor Stock
A4936METTR-T 32-lead QFN -20°C to 105°C Yes View Data Discontinued Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.


The device package (suffix ET) is a 32-contact, 5 mm × 5 mm, 0.90 mm nominal overall height QFN, with exposed pad for enhanced thermal dissipation. This small-footprint package is lead (Pb) free, with 100% matte tin leadframe plating. 
ET-QFN with exposed pad 32 contact