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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
s
s
s
s
s
s
Back-EMF commutation provides maximum torque
for minimum “spin-up” time for spindle motors
Accurate, jitter-free phase locked motor speed
feedback output
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
* This Product Is Obsolete
** This Product Is End Of Life As Of August 1, 2000
BLOCK DIAGRAM
20
RC
C
VCO
BACK-EMF
SAMPLER
VCO
PH1
PH2
PH3
22
23
24
14
15
16
21
18
26
VCO/TACH OUT
RESET
I
RAMP
ENABLE E/A
BRAKE
DIS PWR
LOGIC
AND
CONTROL
VCC2
POWER
DRIVERS
4
P1-3
3
GATE
DRIVE
6
3
N1-3
BLDC
MOTOR
8
C
BRK
28
27
7
I
CMD
I
LIMIT
PWR FAIL
+5
VCC
LINEAR OR PWM
CURRENT CONTROL
I
SENSE
C
OS
12
PATENTED
13
6
17
19
25
POWER
FAIL
DETECT
C
OTA
GND
1
REV. 1.0 10/10/2000
ML4411/ML4411A
PIN CONFIGURATION
ML4411
28-Pin SOIC (S28W)
GND
P1
P2
VCC2
P3
C
OTA
C
BRK
DIS PWR
N1
N2
N3
I
SENSE
C
OS
C
VCO
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
I
CMD
I
LIMIT
BRAKE
VCC
PH3
PH2
PH1
I
RAMP
RC
+5V
ENABLE E/A
PWR FAIL
RESET
VCO/TACH OUT
TOP VIEW
PIN DESCRIPTION
PIN NAME
FUNCTION
PIN NAME
FUNCTION
1
2
3
4
5
6
7
GND
P1
P2
V
CC2
P3
C
OTA
C
BRK
Signal and Power Ground
Drives the external P-channel
transistor driving motor PH1
Drives the external P-channel
transistor driving motor PH2
12V power and power for the
braking function
Drives the external P-channel
transistor driving motor PH3
Compensation capacitor for linear
motor current amplifier loop
Capacitor which stores energy to
charge N-channel MOSFETs for
braking with power off.
A logic 0 on this pin turns off the N
and P outputs and causes the TACH
comparator output to appear on TACH
OUT
16
RESET
Input which holds VCO off and sets the
IC to the RESET condition
17
PWR FAIL
A “0” output indicates 5V or 12V is
under-voltage. This is an open
collector output with a 4.5kΩ pull-up
to +5V
18 ENABLE E/A A ”1” logic input enables the error
amplifier and closes the back-EMF
feedback loop
19 +5V
20 RC
21 I
RAMP
5V power supply input
VCO loop filter components
Current into this pin sets the initial
acceleration rate of the VCO during
start-up
Motor Terminal 1
Motor Terminal 2
Motor Terminal 3
12V power supply. Terminal which is
sensed for power fail
A ”0” activates the braking circuit
Sets the threshold for the PWM
comparator
Current Command for Linear Current
amplifier
8
DIS PWR
22 PH1
23 PH2
24 PH3
25 V
CC
26
BRAKE
27 I
LIMIT
28 I
CMD
9-11 N1, N2 N3 Drives the external N-channel
MOSFETs for PH1, PH2, PH3
12 I
SENSE
13 C
OS
14 C
VCO
Motor current sense input
Timing capacitor for fixed off-time
PWM current control
Timing capacitor for VCO
15 VCO/TACH Logic Output from VCO or TACH
OUT
comparator
2
REV. 1.0 10/10/2000
ML4411/ML4411A
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 (pins 2, 3, 5, 9,10,11) ................
±150mA
Logic Inputs (pins 16, 17, 18, 25) ..................... –0.3 to 7V
Junction Temperature ............................................. 150°C
Storage Temperature Range ..................... –65°C to 150°C
Lead Temperature (Soldering 10 sec.) ..................... 150°C
Thermal Resistance (θ
JA
) ...................................... 60°C/W
OPERATING CONDITIONS
Temperature Range ....................................... 0°C to 70°C
VCC Voltage +12V (pin 25) ............................ 12V
±
10%
+5V (pin 19) ................................................. 5V
±
10%
I(RAMP) current (Pin 21) ................................ 0 to 100µA
I Control Voltage Range (pins 27, 28) ................. 0V to 7V
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, T
A
= Operating Temperature Range, V
CC
= V
CC2
= 12V, R
SENSE
= 1Ω, C
OTA
= C
VCO
= 0.01µF,
C
OS
= 0.02µF
PARAMETER
Oscillator (VCO) Section
(V
PIN16
= 5V)
Frequency vs. V
PIN 20
Frequency
1V
≤
V
PIN20
≤
10V
V
VCO
= 6V
V
VCO
= 0.5V
Reset Voltage at C
VCO
Sampling Amplifier (Note 1)
V
RC
I
RC
State R
V
PIN18
= 0V, R
RAMP
= 39kΩ
V
PIN18
= 5V, State A, V
PH2
= 4V
V
PIN18
= 5V, State A, V
PH2
= 6V
V
PIN18
= 5V, State A, V
PH2
= 8V
V
PIN21
Motor Current Control Section
I
SENSE
Gain
One Shot Off Time
I
CMD
Transconductance Gain
I
CMD
, I
LIM
Bias Current
Power Fail Detection Circuit
12V Threshold
Hysteresis
5V Threshold
Hysteresis
Logic Inputs
Voltage High (V
IH
)
Voltage Low (V
IL
)
Current High (I
IH
)
Current Low (I
IL
)
V
IN
= 2.7V
V
IN
= 0.4V
–10
–500
1
–350
2
0.8
10
–200
V
V
µA
µA
3.8
9.1
9.8
150
4.25
70
4.5
10.5
V
mV
V
mV
V
IN
= 0
0
V
PIN27
= 5V, 0V
≤
V
PIN28
≤
2.5V
4.5
12
5
25
0.19
–100
–400
5.5
33
V/V
µs
mmho
nA
R
PIN21
= 39kΩ to +5V
70
30
–13
–30
1.0
125
100
50
2
–50
1.1
250
130
90
13
–90
1.20
mV
µA
µA
µA
µA
V
Mode = 0
1450
70
300
1800
140
125
2150
210
250
Hz/V
Hz
Hz
mV
CONDITIONS
MIN
TYP
MAX
UNITS
REV. 1.0 10/10/2000
3
ML4411/ML4411A
ELECTRICAL CHARACTERISTICS
(Continued)
PARAMETER
Braking Circuit
(V
PIN17
= 0V)
Brake Active Threshold
PIN 26 Bias Current
N-Channel Leakage
C
BRK
Current
Outputs
(I
CMD
= I
LIMIT
= 2.5V)
I
P
Low
V
P
= 0.8V
V
P
= 0.4V
V
P
High
P3 Comparator Threshold
V
N
High
V
N
Low
LOGIC Low (V
OL
)
VCO/TACH V
OH
POWER FAIL V
OH
Supply Currents
(N and P Outputs Open)
5V Current
V
CC
Current
V
CC2
Current
V
CC2
Current
Note 1.
For explanation of states, see Figure 5 and Table 1.
CONDITIONS
MIN
TYP
MAX
UNITS
0.8
V
PIN26
= 0V
V
CC
, V
CC2
= 0V
V
PIN17
= 0V, V
N
= 4V
V
CC
, V
CC2
= 0V, V
PIN26
= 3V
V
PIN7
= 6V
5
2
V
CC
– 0.4
V
CC2
– 1.6
V
PIN12
= 0V
I
N
= 1mA
I
OUT
= 0.4mA
I
OUT
= –100µA
I
OUT
= –10µA
2.4
V
CC2
– 3.2
0
1.2
0.3
0.06
20
1.6
1
10
85
V
µA
nA
µA
7
4
19.5
mA
mA
V
I
P
= –10µA
V
CC2
– 0.8
10
0.2
V
CC
– 1.2
0.7
0.5
V
V
V
V
V
V
PIN19
– 0.2 V
PIN19
– 0.1
3
38
V
PIN19
4
50
3
3.75
V
mA
mA
mA
mA
ML4411
ML4411A
2
2.6
4
REV. 1.0 10/10/2000
