View ba6477fs datasheet:

Motor driver ICs FDD spindle motor driver BA6477FS The BA6477FS is a one-chip IC designed for driving 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 com- pactly packaged IC reduces the number of external components required. FApplications Floppy disk drivers FFeatures 1) 3-phase, full-wave soft switching drive system. 4) Hall power supply switch. 2) Digital servo circuit. 5) Motor speed changeable. 3) Power save circuit. 6) Index amplifier. FAbsolute maximum ratings (Ta = 25_C) FRecommended operating conditions (Ta = 25_C) 532 Motor driver ICs BA6477FS FBlock diagram 533 Motor driver ICs BA6477FS FPin descriptions 534 Motor driver I