ML4411CS Microsemi Corporation, ML4411CS Datasheet

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ML4411CS

Manufacturer Part Number
ML4411CS
Description
Manufacturer
Microsemi Corporation
Datasheet

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ML4411CS
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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.
BLOCK DIAGRAM
20
14
15
16
21
18
26
28
27
17
19
25
8
RC
VCO/TACH OUT
C
RESET
I
ENABLE E/A
BRAKE
DIS PWR
I
I
PWR FAIL
+5
VCC
RAMP
CMD
LIMIT
VCO
POWER
DETECT
FAIL
VCO
CONTROL
CURRENT CONTROL
LOGIC
LINEAR OR PWM
AND
Sensorless Spindle Motor Controller
6
BACK-EMF
SAMPLER
DRIVE
GATE
3
3
The ML4411A includes a comparator on the P3 output to
prevent cross-conduction.
FEATURES
* This Product Is Obsolete
** This Product Is End Of Life As Of August 1, 2000
VCC2
I
C
SENSE
GND
N1-3
C
P1-3
PH1
PH2
PH3
C
OTA
BRK
OS
Back-EMF commutation provides maximum torque
for minimum “spin-up” time for spindle motors
Accurate, jitter-free phase locked motor speed
Linear or PWM motor current control
Easy microcontroller interface for optimized start-up
sequencing and speed control
Power fail detect circuit with delayed braking
Drives external N-channel FETs and P-channel FETs
Back-EMF comparator detects motor rotation after
power fail for fast re-lock after brownout
22
23
24
12
13
4
7
6
1
feedback output
ML4411*/ML4411A**
DRIVERS
POWER
PATENTED
MOTOR
BLDC
May 1997
1

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ML4411CS Summary of contents

Page 1

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 ...

Page 2

ML4411/ML4411A PIN CONFIGURATION PIN DESCRIPTION PIN NAME FUNCTION 1 GND Signal and Power Ground 2 P1 Drives the external P-channel transistor driving motor PH1 3 P2 Drives the external P-channel transistor driving motor PH2 4 V 12V power and power ...

Page 3

ABSOLUTE MAXIMUM RATINGS Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. Supply Voltage (pins 4, 25) ........................................ 14V Output Current ...

Page 4

ML4411/ML4411A ELECTRICAL CHARACTERISTICS PARAMETER Braking Circuit (V = 0V) PIN17 Brake Active Threshold PIN 26 Bias Current N-Channel Leakage C Current BRK Outputs ( 2.5V) CMD LIMIT I Low P V High P P3 Comparator Threshold V ...

Page 5

FUNCTIONAL DESCRIPTION The ML4411 provides closed-loop commutation for 3-phase brushless motors. To accomplish this task, a VCO, integrating Back-EMF Sampling error amplifier and sequencer form a phase-locked loop, locking the VCO to the back-EMF of the motor. The IC also ...

Page 6

Minute. ML4411/ML4411A The minimum VCO gain derived from the specification table (using the minimum Fvco at V VCO . VCO MIN ( ) C VCO Assuming that the V = 9.5V, then VCO(MAX ...

Page 7

STATE OFF ON A OFF OFF B OFF OFF C ON OFF D ON OFF E OFF ON F OFF ON RESET 4 VCO 2.3 V VCO OUT R 0 STATE Step 1a: ...

Page 8

ML4411/ML4411A The motor will start more consistently and tolerate a wider variation in open loop step rate if there is some damping on the motor (such as head drag) during the open loop modes. The tolerance of the open loop ...

Page 9

BRAKING As shown in figure 9, the braking circuit pulls the N- Channel MOSFET gates high when BRAKE falls below a 1.4V threshold. After a power failure, C slowly through R providing a delay for retract to occur DLY before ...

Page 10

ML4411/ML4411A APPLICATIONS Figure 10 shows a typical application of the ML4411 in a hard disk drive spindle control. Although the timing necessary to start the motor in most applications would be generated by a microcontroller, Fig. 11 shows a simple ...

Page 11

R1 ML4411 1/6 PIN 17 IC1 Figure 11. Analog Start-up Circuit – ML4411 + PIN +12V – SYMBOL VALUE SYMBOL A1 LM358 R4 IC1 74HC14 ...

Page 12

ML4411/ML4411A 10K 10K 10K +V +V 1.2K 0.01 0.5 In unipolar operation, the motor‘s windings must be allowed to drive freely to (MAX) SUPPLY (MAX) Therefore, there can be no diodes to clamp the inductive ...

Page 13

HIGHER VOLTAGE MOTOR DRIVE To drive a higher voltage motor, the same precautions regarding ML4411 voltage limitations as were outlined for Unipolar drive above should be followed. Figures 14–16 provide several methods of translating the ML4411‘s P outputs to drive ...

Page 14

... ORDERING INFORMATION PART NUMBER ML4411CS (Obsolete) ML4411ACS (End Of Life) © Micro Linear 1997 is a registered trademark of Micro Linear Corporation Products described in this document may be covered by one or more of the following patents, U.S.: 4,897,611; 4,964,026; 5,027,116; 5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; ...

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