Motor driver ICs 3-phase motor driver for CD-ROMs BA6848FP / BA6853FS The BA6848FP and BA6853FS are single-chip ICs developed for CD-ROM spindle motor drives. These ICs are 3phase, full-wave, pseudo-linear drives with FG output, FG composite output, and reverse-rotation pins built-in for high functionality and high performance. Applications CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM Features 1) Three-phase, full wave, pseudo-linear drive system. 2) Built-in PS pin for power save mode when ON. 3) Built-in thermal shutdown and current limiter circuits. 4) Built-in Hall bias circuit (for the BA6848FP). 5) Built-in FG output and FG composite output. 6) Built-in reverse-rotation pin. Absolute maximum ratings (Ta = 25C) Recommended operating conditions (Ta = 25C) 781 Motor driver ICs Block diagram 782 BA6848FP / BA6853FS Motor driver ICs Pin descriptions BA6848FP BA6848FP / BA6853FS BA6853FS 783 Motor driver ICs I / O circuit diagrams (1) Power save(PS) BA6848FP / BA6853FS (4) Coil output (A1, A2, A3) (2) Reverse (REV) (5) Hall input (H1, H1, H2, H2, H3, and H3) (3) Torque command input (6) Hall bias Note: Resistances are typical values. 784 Motor driver ICs BA6848FP / BA6853FS Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 5V, VM1 = 12V, VM2 = 12V) 785 Motor driver ICs BA6848FP / BA6853FS Circuit operation (1) Hall input and output The phase relationship between the Hall input signals and the output current and voltage is shown below in Fig.7. The input three-phase Hall signal is sent to the matrix section for waveform synthesis. This signal is input to the output driver and supplies the drive current to the motor coil. 786 Motor driver ICs BA6848FP / BA6853FS (2) Torque command The RNF pin voltage with respect to the torque command (EC) is as follows: The I / O gain GEC from EC pin to RNF pin (output current) is determined by the RNF detector resistance. GEC = 0.255 / RNF [A / V] The torque limit current ITL is: ITL = 0.35 / RNF [A] 787 Motor driver ICs BA6848FP / BA6853FS (3) FG signal output waveform From the Hall input signal, a pulse signal (FG signal) is output proportional to the motor speed of rotation. This timing is shown in Fig.9 below. (4) Other For the PS pins, the circuits turn on at 3.5 V or greater, and enter the power save mode at 1.5 V or less. For the REV pin, it enters the reverse mode at 4.0 V or greater, and enters the normal mode at 1.5 V or less. 788 Motor driver ICs BA6848FP / BA6853FS Application example 789 Motor driver ICs Operation notes (1) Power save The power save input is an input / output circuit as shown in Fig.1. The power save pins have a thermal derating characteristic of 8mV / C. The resistance also has a fluctuation of ±30%, so be careful of the input voltage range. (2) Reverse The reverse input is an input / output circuit as shown in Fig.2. The reverse pins have a thermal derating characteristic of 7mV / C. The resistance also has a fluctuation of ±30%, so be careful of the input voltage range. (3) Hall input The Hall input is an input circuit as shown in Fig.5. The Hall elements can be connected in series or in parallel. (4) Thermal shutdown (TSD) When the junction temperature reaches 175C (Typ.), the A1 to A3 coil outputs become open. There is an approximate 15C (Typ.) temperature hysteresis. 790 BA6848FP / BA6853FS Motor driver ICs BA6848FP / BA6853FS Electrical characteristic curves External dimensions (Units: mm) 791