ML4426
PIN DESCRIPTION
PIN
NAME
(Pin number in parenthesis is for TQFP package)
PIN
NAME
FUNCTION
FUNCTION
1(30)
I
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
Active low output driver for the
phase A high-side switch
Active low output driver for the
phase B high-side switch
Active low output driver for the
phase C high-side switch
17(17) C
AT
A capacitor to GND sets the time
that the controller stays in the
align mode
This output goes low when V
DD
drops below the UVLO threshold,
and indicates that all output
drivers have been disabled
A capacitor to GND sets the time
that the controller stays in the
ramp mode
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
A capacitor to between C
RR
and
SPEED FB sets the ramp rate
(acceleration) of the motor when
the controller is in ramp mode
The motor feedback voltage from
phase A is monitored through a
resistor divider for back-EMF
sensing at this pin
The motor feedback voltage from
phase B is monitored through a
resistor divider for back-EMF
sensing at this pin
The motor feedback voltage from
phase C is monitored through a
resistor divider for back-EMF
sensing at this pin
A logic low input activates motor
braking by shutting off the high-
side output drivers and turning on
the low-side output drivers
A capacitor to GND sets the time
that the low-side output drivers
remain off after I
SENSE
exceeds its
threshold
An 137kW resistor to GND sets a
current proportional to V
REF
that is
used to set all the internal bias
currents except for the VCO
Signal and power ground
18(18)
UV FAULT
2(31)
3(32)
4(1)
5(3)
HA
HB
HC
19(19) C
RT
20(20) SPEED FB
SPEED COMP Speed control loop compensation is
set by a series resistor and capacitor
from SPEED COMP to GND
C
T
V
REF
SPEED SET
A capacitor from C
T
to GND sets
the PWM oscillator frequency
6.9V reference voltage output
Speed loop input which ranges
from 0 (stopped) to V
REF
(maximum speed)
Active high output driver for the
phase A low-side switch
Active high output driver for the
phase B low-side switch
Active high output driver for the
phase C low-side switch
24(24) FB C
This TTL level input selects the
direction of the motor by changing
the sequence of the commutation
state machine
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
12V power supply input
A capacitor to GND sets the
voltage-to-frequency ratio of the
VCO
An resistor to GND sets up a
current proportional to the input
voltage of the VCO
27(27) R
REF
23(23) FB B
21(21) C
RR
6(4)
7(5)
8(6)
22(22) FB A
9(7)
10(8)
11(9)
LA
LB
LC
12(10) F/R
25(25)
BRAKE
13(11) VCO/TACH
26(26) C
IOS
14(12) V
DD
15(15) C
VCO
16(16) R
VCO
28(28) GND
3
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
