MC33033 View Datasheet(PDF) - ON Semiconductor
Part Name
Description
Manufacturer
MC33033 Datasheet PDF : 27 Pages
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MC33033, NCV33033
Brush Motor Control
Though the MC33033 was designed to control brushless dc
motors, it may also be used to control dc brush−type motors.
Figure 45 shows an application of the MC33033 driving a
H−bridge affording minimal parts count to operate a
brush−type motor. Key to the operation is the input sensor
code [100] which produces a top−left (Q1) and a bottom−right
(Q3) drive when the controller’s Forward/Reverse pin is at
logic [1]; top−right (Q4), bottom−left (Q2) drive is realized
when the Forward/Reverse pin is at logic [0]. This code
supports the requirements necessary for H−bridge drive
accomplishing both direction and speed control.
The controller functions in a normal manner with a pulse
width modulated frequency of approximately 25 kHz.
Motor speed is controlled by adjusting the voltage presented
to the noninverting input of the Error Amplifier establishing
the PWM′s slice or reference level. Cycle−by−cycle current
limiting of the motor current is accomplished by sensing the
voltage (100 mV threshold) across the RS resistor to ground
of the H−bridge motor current. The over current sense circuit
makes it possible to reverse the direction of the motor, on the
fly, using the normal Forward/Reverse switch, and not have
to completely stop before reversing.
LAYOUT CONSIDERATIONS
Do not attempt to construct any of the motor control
circuits on wire−wrap or plug−in prototype boards. High
frequency printed circuit layout techniques are imperative to
prevent pulse jitter. This is usually caused by excessive noise
pick−up imposed on the current sense or error amp inputs.
The printed circuit layout should contain a ground plane
with low current signal and high drive and output buffer
grounds returning on separate paths back to the power
supply input filter capacitor VM. Ceramic bypass capacitors
(0.01 μF) connected close to the integrated circuit at VCC,
Vref and error amplifier noninverting input may be required
depending upon circuit layout. This provides a low
impedance path for filtering any high frequency noise. All
high current loops should be kept as short as possible using
heavy copper runs to minimize radiated EMI.
4
5
6
FWR/REV
Enable
+12 V
0.1
3
18
19
14
Reference
Regulator
7
Rotor
Position
Decoder
Undervoltage
Lockout
10 k
Faster
10 k
9 Error Amp
10
PWM
11
Thermal
Shutdown
R
Q
S
0.005
8
Oscillator
S
Q
ILimit
R
2
+12 V
1.0 k
1
Q1* 1.0 k
20
Q4*
DC Brush
Motor
17
22
16
M
Q2*
15
12
1.0 k
0.001
Q3*
22
RS
13 Gnd
Figure 45. H−Bridge Brush−Type Controller
http://onsemi.com
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