Patent ID: 7750596
Filing Date: 2010-07-06
Classification: H02P

Abstract:
1. A semiconductor device which generates N-phase pulse width modulation signals which control an inverter circuit that drives an N-phase motor, said semiconductor device comprising: a first register which holds N values for determining a period in which each of the N-phase pulse width modulation signals becomes active, the N values respectively corresponding to each of the pulse width modulation signals; a correction buffer which holds N correction values for correcting the period in which each of the pulse width modulation signal becomes active, the N correction values respectively corresponding to each of the N-phase pulse width modulation signals; a first counter which, in each count cycle, counts up from a first count value to a second count value at predetermined time intervals, and counts down from the second count value to the first count value at predetermined time intervals after the count up; N second counters, each of which respectively corresponds to each of the N-phase pulse width modulation signals and counts a value obtained by temporally advancing or delaying a count value of said first counter by a corresponding correction value; N selectors, each of which selects a count value of the first counter in a case where correction is not performed on a period in which a corresponding N-phase pulse width modulation signal becomes active, and selects a count value of the corresponding second counter in the case where correction is performed on the period in which the corresponding N-phase pulse width modulation signal becomes active; N comparison units, each of which is operable to judge whether or not the count value of the first counter or second counter selected by each of said selectors matches the corresponding value held by said first register; and a pulse width modulation control unit operable to generate each of the N-phase pulse width modulation signals, logical values of which are switched at a timing when said comparison unit judges that the count value matches the held value.