Description
The A4931 is a complete 3-phase brushless DC motor pre-driver.
The device is capable of driving a wide range of N-channel
power MOSFETs and can support motor supply voltages up to
30 V. Commutation logic is determined by three Hall-element
inputs spaced at 120°.
Other features include fixed off-time pulse width modulation
(PWM) current control for limiting inrush current, locked-rotor
protection with adjustable delay, thermal shutdown, overvoltage
monitor, and synchronous rectification. Internal synchronous
rectification reduces power dissipation by turning on the
appropriate MOSFETs during current decay, thus shorting
the body diode with the low R
DS(on)
MOSFET. Overvoltage
protection disables synchronous rectification when the motor
pumps the supply voltage beyond the overvoltage threshold
during current recirculation.
The A4931 offers enable, direction, and brake inputs that can
control current using either phase or enable chopping. Logic
outputs FG1 and FG2 can be used to accurately measure motor
rotation. Output signals toggle state during Hall transitions,
providing an accurate speed output to a microcontroller or
speed control circuit.
Operating temperature range is –20°C to 105°C. The A4931
is supplied in a 5 mm × 5 mm, 28-terminal QFN package with
exposed thermal pad. This small footprint package is lead (Pb)
free with 100% matte tin leadframe plating.
4931-DS, Rev. 6
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
3-Phase Brushless DC Motor Pre-Driver
Package: 28-contact QFN (ET package)
Typical Application
A4931
Approximate Scale 1:1
M
VBB
0.1 μF
0.1 μF
0.1 μF
0.1 μF
2 kΩ
V
IN
V
IN
FG1
System
Control
Logic
FG2
A4931
HBIAS
DIR
GND
BRAKEZ
ENABLE
CP1CLD CP2 VCP
GLA
SA
GHA
GLB
SB
GHB
GLC
SC
GHC
SENSE
HA+ HA– HB+ HB– HC+ HC–
