BA6486FS

Motor driver ICs FDD spindle motor driver BA6486FS The BA6486FS is a one-chip IC designed for driving 12V FDD spindle motors. This high-performance IC employs a 3-phase, full-wave soft switching drive system, and contains a digital servo, an index amplifier, and a power save circuit. The compactly packaged IC reduces the number of external components required. FApplications Floppy disk drivers FFeatures 1) 12V supply voltage. 2) 3-phase, full-wave soft switching drive system. 3) Digital servo circuit. 4) Power save circuit. FAbsolute maximum ratings (Ta = 25_C) 5) Hall power supply switch. 6) Motor speed changeable. 7) Index amplifier. FRecommended operating conditions (Ta = 25_C) 544 Motor driver ICs FBlock diagram BA6486FS 545 Motor driver ICs FPin descriptions BA6486FS FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 12V) 546 Motor driver ICs BA6486FS FCircuit operation (1) Motor drive circuit The motor driver is based on a 3-phase, full-wave soft switching, current drive system in which the position of rotor is sensed by Hall elements. The total drive current of motor is sensed by a small resistor (RNF) and regulated through a voltage comparison. The IC consists of Hall amplifiers, an amplitude control circuit, a driver, an error amplifier, and current feedback ampifier (Fig. 1). The waveforms of different steps along the signal path from the Hall elements to the motor driver output are shown in Fig. 2. The Hall amplifiers receive the Ha...