Datasheet BA6813F, BA6811F Datasheet (ROHM)

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 = 25C)
4) Alarm output pin. (BA6811F)
5) Hall signal output pin. (BA6813F)
6) Built-in reverse current protection diode.
Recommended operating conditions (Ta = 25C)
712
Motor driver ICs BA6811F / BA6813F
Block diagram
Pin descriptions
Hall input / output truth table
713
Motor driver ICs BA6811F / BA6813F
Input / output equivalent circuits
Electrical characteristics (unless otherwise noted, Ta = 25C, V
CC = 12V)
714
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 (V
TON (Charge time)=
TOFF (Discharge time)=
LDCLVLDCP)
I
LDC
LDCLVLDCP)
C S (V
ILDD
where V
LDCL is the LD-pin clamp voltage (1.93V), LDCP is the LD-pin comparator voltage (0.76V),
V
LDC is the LD-pin charge current (2.9µA),
I
LDD is the LD-pin discharge current (0.52µA),
I 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.
(Typical value)
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 175C (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 :
P
C=PC1)PC2)PC3
C1 is power consumed by the circuit current.
P
C1=VCC ICC
P
PC2 is the output current consumption.
P
C2=VOL IO
VOL is the LOW level output voltage of output pins 1 and 2, and I
C3 is power consumed by the AL and HO pins.
P
C3=VALL IAL)VHOL IHO /2
P
O is the sink current of pins 1 and 2.
where V
ALL is the AL-pin LOW level voltage,
AL is the AL-pin sink current,
I
HOL is the HO-pin LOW level voltage,
V
HO is the HO-pin sink current.
I Make sure that your application does not exceed the al­lowable power dissipation of the IC.
Motor driver ICs BA6811F / BA6813F
(3)Hall amplifier input voltage
The R1 and R2 resistances must be set so as to maintain the Hall amplifier input bias voltage within the range of 0V
CC*2.8V) including the signal amplitude.
to (V 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.
Hall current is given by :
where RH is the Hall device impedance.
VCC
R1)R2)RH
External dimensions (Units: mm)
717
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