Abstract: A method for data window centering a multifrequency data separator (12) based on having the frequency of a voltage-controlled oscillator (20) at least twice that of read data window frequency, and setting delay of a delay line (14) used in the data separating process so that arriving raw data pulses will be more accurately assigned to their corresponding windows. The method is realized by providing the multifrequency data separator with a phase comparator emulator (30) and a counter (28). According to another embodiment, the apparatus comprises a counter (28b) combined with a delay setting logic unit (40). The method and apparatus described above result in window centering which does not essentially depend on timing characteristics of circuitry used in the construction of the data separator.

Abstract: A current driver circuit for an inductive load, such as a motor winding, provides unidirectional, controlled current through the winding by use of two pulse width modulator switches on opposite sides of the winding or bidirectional current control by use of two pairs of pulse width modulated switches; each pair straddling the winding relative to the power supply. Each pair of switches is modulated in two different modes to control current during two different operating conditions. The first mode of modulation is used for all but rapidly decaying winding current conditions and a second mode provides control for rapidly decaying winding current. In the first mode, unidirectional current to the winding from the power supply is pulse width modulated while the companion switch of the pair is on.