ML4428 Datasheet, PDF (1/16 Pages) Micro Linear Corporation – Sensorless Smart-Start™ BLDC PWM Motor Controller

April 1997
PRELIMINARY
ML4428*
Sensorless Smart-Start™ BLDC PWM Motor Controller
GENERAL DESCRIPTION
FEATURES
The ML4428 motor controller provides all of the functions
necessary for starting and controlling the speed of delta or
wye-wound Brushless DC (BLDC) Motors without the need
for Hall Effect sensors.
Back-EMF voltage is sensed from the motor windings to
determine the proper commutation phase sequence using
PLL techniques. The patented back-EMF sensing technique
used will commutate virtually any 3-phase BLDC motor that
has at least a 30% variation in inductance during rotation
and is insensitive to PWM noise and motor snubbing
circuitry.
The ML4428 also utilizes a patented start-up technique
which samples the rotor position and applies the proper
drive to accelerate the motor. This ensures no reverse
rotation at start-up and reduces total start-up time.
s Stand-alone operation with forward and reverse
s On-board start sequence: Sense Position Æ Drive Æ
Accelerate Æ Set Speed
s No backward movement at start-up
s Patented back-EMF commutation technique
s Simple variable speed control with on-board reference
s Single external resistor sets all critical currents
s PWM control for maximum efficiency or linear control
for minimum noise
s 12V operation provides direct FET drive for 12V motors
s Drives high voltage motors with high side FET drivers
s Guaranteed no shoot-through when driving external
FET gates directly
* Some Packages Are End Of Life
BLOCK DIAGRAM/TYPICAL APPLICATION
CSC
5
CPWM
6
CISC
21
RREF
27
VREF
7
VSPEED
8
19
RINIT
16
15
RVCO
CVCO
VCO
PWM
SPEED
CONTROL
+
6V
REF
–
RUN
20
RCVCO
0.6V
F/R
12
BRAKE
25
START-UP
AND
COMMUTATION
LOGIC
CSNS
17
PWM CURRENT
CONTROL
AND ONE SHOT
CIOS
26
ISNS
1
14
VCC
9V POWER FAIL
BACK-EMF
SAMPLER
HIGH SIDE
GATE DRIVE
LOW SIDE
GATE DRIVE
GND
28
V_FLT
18
VCO
13
PHI1
22
PHI2
23
PHI3
24
P1
2
P2
3
P3
4
N1
9
N2
10
N3
11
1