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ML4425CSX

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
www.fairchildsemi.com
REV. 1.0.2 7/2/01
Features
• Stand-alone operation
• Motor starts and stops with power to IC
• On-board start sequence: Align
♦
Ramp
♦
Set Speed
• Patented Back-EMF commutation technique provides
jitterless torque for minimum “spin-up” time
• Onboard speed control loop
• PLL used for commutation provides noise immunity from
PWM spikes, compared to noise sensitive zero crossing
technique
• PWM control for maximum efficiency
• Direct FET drive for 12V motors; drives high voltage
motors with IC buffers
General Description
The ML4425 PWM motor controller provides all of the
functions necessary for starting and controlling the speed of
delta or wye wound Brushless DC (BLDC) motors without
Hall Effect sensors. Back EMF voltage is sensed from the
motor windings to determine the proper commutation phase
sequence using a PLL. This patented sensing technique will
commutate a wide range of 3-Phase BLDC motors and is
insensitive to PWM noise and motor snubbing circuitry.
The ML4425 limits the motor current using a constant off-
time PWM control loop. The velocity loop is controlled with
an onboard amplifier. The ML4425 has circuitry to ensure
that there is no shoot-through in directly driven external
power MOSFETs.
The timing of the start-up sequence is determined by the
selection of three timing capacitors. This allows optimization
for a wide range of motors and loads.
Block Diagram
C
AT
17
FB A
22
FB B
23
FB C
24
BACK
EMF
SAMPLER
C
RT
19
–
+
–
+
1.5V
750nA
–
+
1.5V
750nA
V
DD
V
DD
C
RR
21
500nA
V
DD
SPEED
FB
20
C
VCO
15 16
R
VCO
VOLTAGE
CONTROLLED
OSCILLATOR
VCO/TACH
13
2
4
3
9
10
HA
HB
HC
LA
LB
GATING
LOGIC
&
OUTPUT
DRIVERS
+
–
SPEED SET
8
5
SPEED COMP
3.9V
1.7V
20kHz
6
C
T
–
+
1.4V
1
I
SENSE
× 5
UVLO
12
I
LIMIT
–
+
1.7V
V
REF
26
C
IOS
16kΩ
8kΩ
I
LIMIT
1-SHOT
25
BRAKE
V
DD
4kΩ
14
V
DD
28
GND
27
R
REF
11
LC
REFERENCE
VCO
OUT
VCO
OUT
18
UV FAULT
7
V
REF
A
B
C
D
E
F
R
COMMUTATION
STATE MACHINE
ML4425
Sensorless BLDC Motor Controller
ML4425 PRODUCT SPECIFICATION
2
REV. 1.0.2 7/2/01
Pin Description
Pin Name Function
1I
SENSE
Motor current sense input. When I
SENSE
exceeds 0.2
↔
I
LIMIT,
the output drivers LA,
LB, and LC are shut off for a fixed time determined by C
IOS
.
2HA
Active low output driver for the phase A high-side switch.
3HBActive low output driver for the phase B high-side switch.
4HCActive low output driver for the phase C high-side switch.
5 SPEED
COMP
Speed control loop compensation is set by a series resistor and capacitor from
SPEED COMP to GND.
6C
T
A capacitor from C
T
to GND sets the PWM oscillator frequency.
V
REF
6.9V reference voltage output.
8 SPEED SET Speed loop input which ranges from 0 (stopped) to V
REF
(maximum speed).
9 LA Active high output driver for the phase A low-side switch.
10 LB Active high output driver for the phase B low-side switch.
11 LC Active high output driver for the phase C low-side switch.
12 I
LIMIT
Voltage on this pin sets the I
SENSE
threshold voltage at 0.2
↔
I
LIMIT
, leaving this pin
unconnected selects an internally set threshold.
13 VCO/TACH This TTL level output corresponds to the signal used to clock the commutation state
machine. The output frequency is proportional to the motor speed when the back-
EMF sensing loop is locked onto the rotor position.
14 V
DD
12V power supply input.
15 C
VCO
A capacitor to GND sets the voltage-to-frequency ratio of the VCO.
Pin Configuration
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
SENSE
HA
HB
HC
SPEED COMP
C
T
V
REF
SPEED SET
LA
LB
LC
I
LIMIT
VCO/TACH
V
DD
GND
R
REF
C
IOS
BRAKE
FB C
FB B
FB A
C
RR
SPEED FB
C
RT
UV FAULT
C
AT
R
VCO
C
VCO
TOP VIEW
ML4425
28-Pin Narrow PDIP (P28N)
28-Pin SOIC (S28)
PRODUCT SPECIFICATION ML4425
REV. 1.0.2 7/2/01
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.
Operating Conditions
16 R
VCO
An resistor to GND sets up a current proportional to the input voltage of the VCO.
17 C
AT
A capacitor to GND sets the time that the controller stays in the align mode.
18 UV
FAULT This output goes low when V
DD
drops below the UVLO threshold, and indicates that
all output drivers have been disabled.
19 C
RT
A capacitor to GND sets the time that the controller stays in the ramp mode.
20 SPEED FB Output of the back-EMF sampling circuit and input to the VCO. An RC network
connected to SPEED FB sets the compensation for the PLL loop formed by the
back-EMF sampling circuit, the VCO, and the commutation state machine.
21 C
RR
A capacitor to between C
RR
and SPEED FB sets the ramp rate (acceleration) of the
motor when the controller is in ramp mode.
22 FB A The motor feedback voltage from phase A is monitored through a resistor divider for
back-EMF sensing at this pin.
23 FB B The motor feedback voltage from phase B is monitored through a resistor divider for
back-EMF sensing at this pin.
24 FB C The motor feedback voltage from phase C is monitored through a resistor divider for
back-EMF sensing at this pin.
25 BRAKE A logic low input activates motor braking by shutting off the high-side output drivers
and turning on the low-side output drivers.
26 C
IOS
A capacitor to GND sets the time that the low-side output drivers remain off after
I
SENSE
exceeds its threshold .
27 R
REF
An 137k
Ω
resistor to GND sets a current proportional to V
REF
that is used to set all
the internal bias currents except for the VCO.
28 GND Signal and power ground.
Parameter Min. Max. Units
V
DD
14 V
Logic Inputs (SPEED FB, BRAKE) GND – 0.3 7 V
All Other Inputs and Outputs GND – 0.3 V
DD
+ 0.3 V
Output Current (LA, LB, LC, HA
, HB, HC
)
±50 mA
Junction Temperature 150 °C
Storage Temperature Range -65 150 °C
Lead Temperature (Soldering 10 sec.) 260 °C
Thermal Resistance (
θ
JA
)
28-Pin Narrow PDIP
28-Pin SOIC
48
75
°C/W
°C/W
Parameter Min. Max. Units
Temperature Range
ML4425CX
ML4425IX
0
–40
70
85
°C
°C
V
DD
10.8 13.2 V
Pin Description
(continued)
Pin Name Function
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

ML4425CSX

Mfr. #:
Buy ML4425CSX
Manufacturer:
ON Semiconductor / Fairchild
Description:
Motor / Motion / Ignition Controllers & Drivers SENSORLESS BLDC PWM MOTOR CONTROLLER
Lifecycle:
New from this manufacturer.
Delivery:
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