BA6848FP

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. FApplications CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM FFeatures 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. FAbsolute maximum ratings (Ta = 25_C) 4) Built-in Hall bias circuit (for the BA6848FP). 5) Built-in FG output and FG composite output. 6) Built-in reverse-rotation pin. FRecommended operating conditions (Ta = 25_C) 781 Motor driver ICs FBlock diagram BA6848FP / BA6853FS 782 Motor driver ICs FPin descriptions BA6848FP BA6848FP / BA6853FS BA6853FS 783 Motor driver ICs FI / 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 FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 5V, VM1 = 12V, VM2 = 12V) 785 Motor driver ICs BA6848FP / BA6853FS FCircuit 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 (2) Torque command The RNF pin voltage with respect to the torque command (EC) is as follows: BA6848FP / BA6853FS 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 FApplication example BA6848FP / BA6853FS 789 Motor driver ICs FOperation 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. BA6848FP / BA6853FS (4) Thermal shutdown (TSD) When the junction temperature reaches 175_C (Typ.), the A1 to A3 coil outputs become open. There is an approximate 15_C (Typ.) temperature hysteresis. 790 Motor driver ICs FElectrical characteristic curves BA6848FP / BA6853FS FExternal dimensions (Units: mm) 791