1. MC3479P Stepper Motor and Stepper Motor IC
Dantai Vilairoj
November 18th, 2002

2. Pin Description Vd: Clamp Diode Voltage
Pins 2, 3, 14, 15: Driver Outputs
L1 & L2 are connected to one coil
L3 & L4 are connected to the other coil
Vm: Power Supply
Bias/Set: used for three functions
determining max output sink current
setting internal logic to known state
reducing power consumption
Vd – Zener diode is used to protect the outputs where large voltage spikes
may occur as the motor coils are switched.
OIC (Output Impedance Control) – only relevant in half step mode
Phase A – when low, driver outputs are in Phase A conditions which means
L1 = L3 = Vohd, L2 = L4 = Vold. (Vohd = Vm – 2.0 & Vold = 0.8

3. Circuit Diagram 470k Ω SIP DIP MC3479P R1-R8: 1k Ω resistors
Q1-Q4: MJE3055T (NPN Transistors)
Q5-Q8: MJE2955T (PNP Transistors)
Transistors

4. Stepper Motor Characteristics
Number of phases: 2
Step Angle: 3.6 degrees
Drive System: bipolar (4 leads)
Holding torque: 600 g-cm
Weight: 0.55 lbs
Motor height: 1.31 in.
Motor diameter: 1.66 in.
Shaft diameter: in.
Shaft length: 0.43 in.
Maximum speed: 7.41 rad/s (Full Step - clk is 4Mhz)
Maximum speed: 3.80 rad/s (Half Step – clk is 4Mhz)

5. Internal Organization
A stepper motor’s shaft has permanent magnets attached to it, together called the rotor. Around the body of the motor, there is a series of coils that create a magnetic field that interact with the permanent magnets. When these coils are turned on and off the magnetic fields causes the rotor to move.
To make a stepper motor rotate, you must constantly turn on and off the coils. If you simply energize one coil the motor will just jump to that position and stay there resisting change. At standstill, steppers generate heat.

6. Bipolar Full Step

7. Bipolar Half Step

8. Applications Data Sheets Automation Robotic Control
Precision Mechanical Control
Data Sheets
(used for different parts: MC3479, , MJE2955T, and MJE3055T)