ML4411 Datasheet, PDF (1/14 Pages) Micro Linear Corporation – Sensorless Spindle Motor Controller

May 1997
ML4411*/ML4411A**
Sensorless Spindle Motor Controller
GENERAL DESCRIPTION
The ML4411 provides complete commutation for delta or
wye wound Brushless DC (BLDC) motors without the need
for signals from Hall Effect Sensors. This IC senses the
back EMF of the three motor windings (no neutral
required) to determine the proper commutation phase
angle using Phase Lock Loop techniques. This technique
will commutate virtually any 3-phase BLDC motor and is
insensitive to PWM noise and motor snubbing. The
ML4411 is architecturally similar to the ML4410 but with
improved braking and brown-out recovery circuitry.
Included in the ML4411 is the circuitry necessary for a
Hard Disk Drive microcontroller driven control loop.
The ML4411 controls motor current with either a constant
off-time PWM or linear current control driven by the
microcontroller. Braking and Power Fail are also included
in the ML4411.
The timing of the start-up sequencing is determined by the
micro, allowing the system to be optimized for a wide
range of motors and inertial loads.
The ML4411 modulates the gates of external N-Channel
power MOSFETs to regulate the motor current. The IC
drives P-Channel MOSFETs directly.
The ML4411A includes a comparator on the P3 output to
prevent cross-conduction.
FEATURES
s Back-EMF commutation provides maximum torque
for minimum “spin-up” time for spindle motors
s Accurate, jitter-free phase locked motor speed
feedback output
s Linear or PWM motor current control
s Easy microcontroller interface for optimized start-up
sequencing and speed control
s Power fail detect circuit with delayed braking
s Drives external N-channel FETs and P-channel FETs
s Back-EMF comparator detects motor rotation after
power fail for fast re-lock after brownout
* This Product Is Obsolete
** This Product Is End Of Life As Of August 1, 2000
BLOCK DIAGRAM
RC
20
14 ^CVCO
VCO
BACK-EMF
SAMPLER
PH1 ₂₂
PH2 ₂₃
PH3
24
15 ^{VCO/TACH OUT}
16 ^RESET
21 ^IRAMP
ENABLE E/A
18
26 ^BRAKE
DIS PWR
8
LOGIC
AND
CONTROL
6
GATE
DRIVE
28 ^ICMD
27 ^ILIMIT
PWR FAIL
17
19 ⁺⁵
25 ^VCC
LINEAR OR PWM
CURRENT CONTROL
POWER
FAIL
DETECT
VCC2 ₄
P1-3
3
N1-3
3
C_{BRK 7}
ISENSE ₁₂
C_{OS 13}
C_{OTA 6}
GND ₁
POWER
DRIVERS
BLDC
MOTOR
PATENTED
1