A4941 Datasheet, PDF (1/9 Pages) Allegro MicroSystems – The A4941 three-phase motor driver incorporates BEMF sensing to eliminate the requirement for Hall sensors in fan applications.

A4941
Three-Phase Sensorless Fan Driver
Features and Benefits
• Sensorless (no Hall sensors required)
• Soft switching for reduced audible noise
• Minimal external components
• PWM speed input
• FG speed output
• Low power standby mode
• Lock detection
• Optional overcurrent protection
• Variant A automotive qualified to AEC-Q100 Grade 2
Package: 16-pin TSSOP with exposed
thermal pad (suffix LP)
Description
The A4941 three-phase motor driver incorporates BEMF
sensing to eliminate the requirement for Hall sensors in fan
applications.
A pulse wave modulated (PWM) input is provided to control
motor speed, allowing system cost savings by eliminating
external variable power supply. PWM input can also be used
as an on/off switch to disable motor operation and place the
IC into a low power standby mode.
The A4941 is provided in a 16-pin TSSOP package (suffix LP)
with an exposed thermal pad. It is lead (Pb) free, with 100%
matte tin leadframe plating.
Not to scale
Functional Block Diagram
12 V
VCP
0.1 μF
CP1
0.1 μF
CP2
10 μF
VBB
SLEW
PWM
25 kHz
V_BB
FC
O/C
TEST
10 kΩ
FG
+V_INT
Soft
Switch
Control
Logic
OSC
Timers
Startup
OSC
Sequencer
(Direction)
CDCOM
Adaptive
Commutation
Delay
FCOM
Charge
Pump
3-Phase
Half Bridges
OCP
OUTA
OUTB
M
OUTC
SENSE
0.167 Ω
GND
OUTA
CTAP
OUTB
OUTC
GND
BEMF Comparator
A4941-DS, Rev. 4