Datasheet BA6832FS Datasheet (ROHM)

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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. Applications
HDD disc and mass-storage FDD Features
2) Retraction control pin.
Absolute maximum ratings (Ta = 25C)
3) Chip enabling pin.
4) Internal thermal shutdown circuit.
Recommended operating conditions
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Motor driver ICs BA6832FS
Block diagram
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Motor driver ICs BA6832FS
Pin descriptions
Input / output circuits
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Motor driver ICs BA6832FS
Electrical characteristics (unless otherwise noted, Ta = 25C and VCC = 12V)
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Motor driver ICs BA6832FS
Circuit 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 V tween pins 10 and 11 (with reference to pin 10) is con­trolled by the voltage between Vctl (pin 18) and Vref (pin
19) : V
RS=(VctlVref)1 (Typ.)
The output current I
O=(VctlVref) / Rs (Typ.)
I
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 R band width in this case is 80kHz (typical).
(2) When the RTL pin is HIGH
The V the Vrtr (pin 17) voltage (with reference to the ground) :
RS=0.1Vrtr / Rs
V
(3) RTR threshold
The RTR pin threshold voltage is 1.21.3V . The pin has a hysteresis width of about 40mV. (2) Standby mode The standby mode is activated when the CE pin is LOW; the circuit current is reduced to 0.15mA (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 becomes controllable. The pin’s threshold voltage is 1.21.3V. (3) Internal reference voltage The internal reference voltage V
reg=(VCCVF)/2
V
where V and 13) operate with reference to V
RS that develops across the resistor RS be-
O is given by :
S value. The gain
RS voltage (with reference to pin 10) is controlled by
reg is given by :
reg=5.65 when VCC=12V . The output pins (pins 10
reg.
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Motor driver ICs BA6832FS
Application example
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Motor driver ICs BA6832FS
Operation notes (1) Thermal shutdown circuit The IC has a built-in thermal shutdown circuit. The circuit turns off all the driver outputs when the chip junction tem­perature rises to about 175C (typical). There is a tem­perature difference of 20C (typical) between the tem­peratures at which the circuit is activated and deactivated. (2) Vctl, Vref, and input pins If voltage is applied to Vctl (pin 18) and V
CC voltage is outside the operating voltage, the driv-
the V
ref (pin 19) when
er outputs are turned on and a current may flow through the connected motor. The voltage of each input pin should be less than V
CC and more than the ground volt-
age.
Electrical characteristic curves
(3) Temperature dependence of quiescent circuit cur­rent (I
CC)
When the IC temperature rises with Vctl=V CE=LOW in the quiescent mode, I
CC may increase due
ref and
to the temperature dependence of the standby current that flows through the high- and low-side transistors. (4) Package power dissipation The IC power dissipation changes greatly with the supply voltage and the output current. Give full consideration to the power dissipation rating when setting the supply volt­age and the output current.
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Motor driver ICs BA6832FS
External dimensions (Units: mm)
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