BA6832FS Datasheet | ROHM

Motor driver ICs Voice coil motor driver The BA6832FS is a voice coil motor driver used for moving the heads of hard disc and mass-storage floppy disc drives. FApplications HDD disc and mass-storage FDD FFeatures 1) Output current is controlled by the Vctl-Vref voltage. 2) Retraction control pin. FAbsolute maximum ratings (Ta = 25_C) 3) Chip enabling pin. 4) Internal thermal shutdown circuit. FRemended operating conditions Motor driver ICs FBlock diagram Motor driver ICs FPin descriptions FInput / output circuits Motor driver ICs FElectrical characteristics (unless otherwise noted, Ta = 25_C and VCC = 12V) Motor driver ICs FCircuit operation (1) Output current control The method of output current control depends on whether the RTL pin is HIGH or LOW. (1) When the RTL pin is LOW The voltage VRS that develops across the resistor RS between pins 10 and 11 (with reference to pin 10) is controlled by the voltage between Vctl (pin 18) and Vref (pin 19) : VRS=(Vctl- Vref) 1 (Typ.) The output current IO is given by : IO=(Vctl- Vref) / Rs (Typ.) where the positive direction is from pin 13 to pin 10. Therefore, the voltage-current conversion gain for the control input is determined by the RS value. The gain band width in this case is 80k Hz (typical). (2) When the RTL pin is HIGH The VRS voltage (with reference to pin 10) is controlled by the Vrtr (pin 17) voltage (with reference to the ground) : VRS=- 0.1 Vrtr / Rs (3) RTR threshold The RTR pin threshold voltage is 1.2X1.3V. The pin has a hysteresis width of about 40m V. (2) Standby mode The standby mode is activated when the CE pin is LOW; the circuit current is reduced to 0.15m A (typical), and the output pins are put to the high impedance state. The operation mode is activated when the CE pin is HIGH, and the output current bees controllable. The pin’s threshold voltage is 1.2X1.3V. (3) Internal reference voltage The internal reference voltage Vreg is given by...