BA6832FS

Motor driver ICs Voice coil motor driver BA6832FS 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. FRecommended operating conditions 509 Motor driver ICs FBlock diagram BA6832FS 510 Motor driver ICs FPin descriptions BA6832FS FInput / output circuits 511 Motor driver ICs FElectrical characteristics (unless otherwise noted, Ta = 25_C and VCC = 12V) BA6832FS 512 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 80kHz (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) ...