PBL3717 bipolar stepper motor driver

A very simple motor stepper driver electronic project can be designed using the PBL3717 motor driver , designed by ST Microelectronics .
The PBL3717A is a monolithic IC which controls and drives one phase of a bipolar stepper motor with chopper control of the phase current. Current levels may be selected in three steps by means of two logic inputs which select one of three current comparators. When both of these inputs are high the device is disabled. A separate logic input controls the direction of current flow.
A monostable, programmed by an external RC network, sets the current decay time.
As you can see in the circuit diagram , this two phase motor stepper driver circuit require two PBL3717 ICs and some other external electronic components .

The output current for this project is up to 1A from 10 up to 46 volt motor supply .
The logic inputs I0 and I1 set at three different levels the amplitude of the current flowing in the motor winding . A high level on the "PHASE" logic input sets the direction of that current from output A to output B and a low level from output B to output A.
It is recommended that unused inputs are tied to pin 6 (Vss) or pin 4 (GND) as appropriate to avoid noise problem.

The current levels can be varied continuously by changing the ref. voltage on pin 11.
The stepper motor can rotate in either directions according to the sequence of the input signals. It is possible to obtain a full step, a half step and a quarter step operation.
In this bipolar stepper motor driver project , the Vss is the logic power and must be around 5 volt and VS is the motor power and must be between 10 and 46 volts .