MC3479 Motorola, MC3479 Datasheet - Page 4

• Manufacturer Part Number: MC3479
• Description: STEPPER MOTOR DRIVER
• Manufacturer: Motorola

General
stepper positioning motor in applications such as disk drives
and robotics. The outputs can provide up to 350 mA to each
of two coils of a two–phase motor. The outputs change state
with each low–to–high transition of the clock input, with the
new output state depending on the previous state, as well as
the input conditions at the logic controls.
14, 15, 16, 17
CW / CCW
4
The MC3479 integrated circuit is designed to drive a
4, 5, 6, 7,
Bias/Set
20–Pin
18, 19
F / HS
2, 3,
20
11
12
10
13
OIC
1
8
9
Clk
Pin No.
Figure 2. AC Test Circuit
56 k
16–Pin
12, 13
14, 15
4, 5,
2, 3,
16
10
11
1
6
7
9
8
+ 12 V
6
7
8
9
10
4
MC3479P
V M
5
16
12 13
Power Supply
Ground
Clamp Diode
Voltage
Driver Outputs
Bias/Set
Clock
Full/Half Step
Clockwise/
Counterclockwise
Output Impedance
Control
Phase A
14
15
2
3
Function
0.1 F
11
L2
L1
L4
L3
4.0 k
1.0 k
1.0 k
1.0 k
1.0 k
1.0 k
1.0 k
+ 12 V
Phase A
APPLICATION INFORMATION
PIN FUNCTION DESCRIPTION
CW/CCW
Symbol
L1, L2
L3, L4
F/HS
Ph A
Gnd
OIC
B/S
V M
Clk
V D
MC3479
Power supply pin for both the logic circuit and the motor coil current.
Voltage range is + 7.2 to + 16.5 volts.
Ground pins for the logic circuit and the motor coil current. The
physical configuration of the pins aids in dissipating heat from within
the IC package.
This pin is used to protect the outputs where large voltage spikes may
occur as the motor coils are switched. Typically a diode is connected
between this pin and Pin 16. See Figure 11.
High current outputs for the motor coils. L1 and L2 are connected to
one coil, and L3 and L4 to the other coil.
This pin is typically 0.7 volts below V M . The current out of this pin
(through a resistor to ground) determines the maximum output sink
current. If the pin is opened (I BS < 5.0 A) the outputs assume a high
impedance condition, while the internal logic presets to a Phase A
condition.
The positive edge of the clock input switches the outputs to the next
position. This input has no effect if Pin 6 is open.
When low (Logic “0”), each clock input pulse will cause the motor to
rotate one full step. When high, each clock pulse will cause the motor
to rotate one–half step. See Figure 7 for sequence.
This input allows reversing the rotation of the motor. See Figure 7 for
sequence.
This input is relevant only in the half step mode (Pin 9 > 2.0 V). When
low (Logic “0”), the two driver outputs of the non–energized coil will be
in a high impedance condition. When high the same driver outputs will
be at a low impedance referenced to V M . See Figure 7.
This open–collector output indicates (when low) that the driver outputs
are in the Phase A condition (L1 = L3 = V OHD , L2 = L4 = V OLD ).
Bias/Set
Input
L1 – L4
Outputs
Outputs
Figure 5), which when connected to a two–phase motor,
provide two full–bridge configurations (L3 and L4 are not
shown in Figure 5). The polarities applied to the motor coils
depend on which transistor (Q H or Q L ) of each output is on,
which in turn depends on the inputs and the decoding
circuitry.
The outputs (L1–L4) are high current outputs (see
0
V M
Figure 3. Bias/Set Timing
Note: t r , t f (10% to 90%) for
input signals are
V M – 1.0
MOTOROLA ANALOG IC DEVICE DATA
(Refer to Figure 2)
Description
t PBSD
PW BS
(High Impedance)
p
25 ns.
V M – 1.0
t PBSD