Rohm BA6811F Fan motor driver ic Datasheet

Motor driver ICs
Fan motor driver IC
BA6811F / BA6813F
The BA6811F and BA6813F are 2-phase, half-wave motor drivers suited for 12V fan motors. Built-in lock detection and
automatic restart mechanisms protect motors. Compact SOP8 (BA6811F / BA6813F) packages reduce the number of
external components required.
Applications
2-phase fan motors
Features
1) Built-in power transistors.
2) Lock detection and automatic restart mechanisms.
3) Built-in thermal shutdown circuit.
Absolute maximum ratings (Ta = 25C)
Recommended operating conditions (Ta = 25C)
712
4) Alarm output pin. (BA6811F)
5) Hall signal output pin. (BA6813F)
6) Built-in reverse current protection diode.
Motor driver ICs
BA6811F / BA6813F
Block diagram
Pin descriptions
Hall input / output truth table
713
Motor driver ICs
Input / output equivalent circuits
Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 12V)
714
BA6811F / BA6813F
Motor driver ICs
BA6811F / BA6813F
FCircuit operation
The BA6811F and BA6813F have motor lock detection
and automatic restart circuits. The timing of lock detection and automatic restart is determined by the external
capacitor connected to the LD pin. The charge time of the
external capacitor is given by :
C S (VLDCLVLDCP)
TON (Charge time)=
ILDC
TOFF (Discharge time)=
C S (VLDCLVLDCP)
ILDD
(Typical value)
where
VLDCL is the LD-pin clamp voltage
(1.93V),
(0.76V),
VLDCP is the LD-pin comparator voltage
(2.9µA),
ILDC is the LD-pin charge current
(0.52µA),
ILDD is the LD-pin discharge current
C is the capacitance of the LD-pin external capacitor.
For C=1µF, for example, the charge (output ON) and discharge (output OFF) times are 0.40s and 2.25s, respectively.
The timing chart for an occasion of motor locking is
shown in Fig. 1.
715
Motor driver ICs
BA6811F / BA6813F
Application example
Operation notes
(1) Thermal shutdown circuit
The IC has a built-in thermal shutdown circuit. The is a
temperature difference of 25C (typical) between the
temperatures at which the circuit is activated and deactivated.
The circuit is activated at the temperature of about 175C
(typical), so that all outputs are turned OFF. Normal operation resumes when the circuit is deactivated.
716
(2) Power consumption
Power consumed in the IC can be calculated from the following equation :
PC=PC1)PC2)PC3
PC1 is power consumed by the circuit current.
PC1=VCC ICC
PC2 is the output current consumption.
PC2=VOL IO
VOL is the LOW level output voltage of output pins
1 and 2, and IO is the sink current of pins 1 and 2.
PC3 is power consumed by the AL and HO pins.
PC3=VALL IAL)VHOL IHO / 2
where
VALL is the AL-pin LOW level voltage,
IAL is the AL-pin sink current,
VHOL is the HO-pin LOW level voltage,
IHO is the HO-pin sink current.
Make sure that your application does not exceed the allowable power dissipation of the IC.
Motor driver ICs
(3)Hall amplifier input voltage
BA6811F / BA6813F
Hall current is given by :
VCC
R1)R2)RH
where RH is the Hall device impedance.
The R1 and R2 resistances must be set so as to maintain
the Hall amplifier input bias voltage within the range of 0V
to (VCC*2.8V) including the signal amplitude.
The Hall device may be affected by power supply noise
due to the PCB conductor pattern. If you have this problem, insert a capacitor C1 as shown in Fig. 5.
If the conductor lines from the Hall device output terminals to the Hall inputs of the IC are particularly long, noise
can be picked up and fed into the inputs. If you have this
problem, insert a capacitor C2 as shown in Fig. 5. Note
that the Hall inputs have no hysteresis in this IC.
External dimensions (Units: mm)
717
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