The present work discusses the development and experimental test of a step motor driver operating in microstepping mode. The work explores two different technologies for the power switching tecnhique. The increassing ability of fast and precise curent switching, brought to the market high performance step motors drivers operating in microstepping resolution. The main advantage of working with microstepping in a smooth operation with very low vibration level when compared with traditional full step of half step driving mode. This fact, made possible to specify step motors to many automatic and robotic systems where only servomotors could be used up to a very short past. In conventional chopper driving, it is necessary to sense the phase current, in order to chop the voltage when the level exceeded. This is done using very small resistor in series with the motor phases. The problem is that the low voltage across the resistor is easily affected by electromagnetic noise giving a false information to the chopper. The present research has explored the possibility of voltage chopping based on fixed timing with the elimination of the whole sensing circuitry. The first results are very encouraging.