A4936 Datasheet, PDF (1/9 Pages) Allegro MicroSystems – 3-Phase Brushless DC Motor Pre-Driver

A4936
3-Phase Brushless DC Motor Pre-Driver
Features and Benefits
• 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
Package: 32-contact QFN (suffix ET)
Not to scale
Description
TheA4936 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.
Continued on the next page…
Typical Application Diagram
V+
System
Control
Logic
A4936
BLDC
Motor
A4936-DS