ML4423 Datasheet, PDF (1/10 Pages) Micro Linear Corporation – 1, 2, or 3-Phase Variable Speed AC Motor Controller

July 2000
ML4423*
1, 2, or 3-Phase Variable Speed AC Motor Controller
GENERAL DESCRIPTION
The ML4423 provides the PWM sinewave drive signals
necessary for controlling three phase AC induction motors as
well as single and two phase split capacitor AC induction
motors.
A constant voltage/frequency ratio can be maintained
over a frequency range of greater than 10:1, providing
15Hz to 150Hz control. The output variable frequency AC
voltages are sensed and fed back to the controller to track the
sinewave frequency and amplitude set at the speed control
input. Direction, on two and three phase motors, is controlled
by changing the relative phase difference between the motor
windings: 90× for two phase motors and 120× and 240× for three
phase motors.
To protect the motor, power devices, high voltage drivers
and control circuitry, the ML4423 includes fixed period,
pulse by pulse variable duty cycle current limit, deadtime
circuitry, and undervoltage lockout. The ML4423 has
selectable output voltage swing of 5V or 12V for
interfacing to different high side drivers and power devices.
FEATURES
s Drives single, two, and three phase AC motors
s Greater than 10:1 variable speed control range
s Constant V/F ratio with programmable end points
s Reverse capability for two and three phase motors
s Low distortion PWM sinewave drive
s Eliminates run capacitors in PSC motors
s Coast function for quick power disable
s Low cost interface for various gate drivers
s PWM current limit, undervoltage lockout, and
programmable deadtime
s 12V ±20% operation with onboard 8V reference
BLOCK DIAGRAM
(* Indicates Part Is End Of Life As Of July 1, 2000)
FB A
1
+
–
FB C
2
FB B
3
+
–
27
SINE A-C
+
–
28
SINE B-C
13
CT
PWM
OSCILLATOR
+
–
CO
12
VSPEED
5
VMIN
4
RSPEED
6
SPEED
CONTROL
SINE A
GENERATOR
SINE C
GENERATOR
SINE B
GENERATOR
15
18
F/R
3PH/2PH
PWM
SINE
WAVE
CONTROL
UVLO
COAST
14
RDT
9
5V/12 SELECT
25
GATING
LOGIC
&
OUTPUT
DRIVERS
COMP
HA
24
HB
22
HC
23
LA
21
LB
19
LC
20
ISENSE
16
0.5V
VDD
26
REFERENCE
GND
RREF
VREF
17
8
7
1