Datasheet BA6402F Datasheet (ROHM)

Motor driver ICs

2-phase half-wave motor predriver

BA6402F

The BA6402F is a 2-phase, half-wave motor predriver suitable for fan motors.
Features

1) Lock detection and rotational speed sensing mecha­nisms are built in.

2) Hall constant current source is built in.

Block diagram and application example

3) Compact 8-pin SOP package reduces the number of
external components required.

Absolute maximum ratings (Ta = 25C)

Recommended operating conditions

689

Motor driver ICs BA6402F

FElectrical characteristics (unless otherwise noted, Ta = 25_C and VCC = 12V)

FRotational speed sensing and lock detection (6 pin)

The circuit around pin 6 is described in Fig. 1. Normally,
the C

6 external capacitor is charging or discharging

around the Hall signal when the motor is running. When
the motor is locked, discharging does not occur at C
cause the Hall signal stops switching. Charging contin­ues at C
voltage, and then Q
With the pin-6 current being constant (I

6 until the voltage increases to the pin-6 clamp

1 turns ON to turn OFF the output.

6=6.8µA, typical),

the time required after the motor is locked until the output
current is turned OFF (duration between B and C in Fig.

2) is determined by the C

Toff=TBC=

6 capacitance.

6CLVBEQ3) C6

(V

I6

4V

BE S C6

6.8µA (Typ.)

6 be-

4.12105C6 (sec) (Typ.)

where V
For C

6CL is pin-6 clamp voltage (nearly equal to 5VBE)

6=2.2µF, for example, Toff is about 0.91s (typical).

FOperation notes
(1) Hall constant current source (3 pin, 6.8mA typical­ly), which is directly connected with the IC bias circuit, is
not available when pin 3 is OPEN (saturated).
(2) Power dissipation
The allowable power dissipation is plotted against ambi­ent temperature in Fig. 3.

690

FThermal derating curve

Motor driver ICs BA6402F

(3) Power dissipation
The power consumed in the IC can be calculated from
the following equation :

3

PC=ΣPCn

n=1

C1 is power consumed by the circuit current.

(1) P

C1=VCCICC

P

(2) PC2 is power consumed by the Hall current (pin 3).

C2=I3V3

P

where V3=pin 3 voltage. Connecting a resistor between

CC pin and pin 3 effectively reduces the IC current

the V
consumption.

Electrical characteristic curve

(3) P

C3 is power consumed by the output current.

C3=(VCCVOH)IO

P
VOH is the HIGH level voltage of pins 7 and 8. Power con­sumption can be reduced by raising the h
external output transistor and thereby reducing the I

FE-rank of the

O val-

ue. Make sure that your application does not exceed the
allowable power dissipation of the IC.
(4) Restarting when motor is locked
The outputs are turned OFF if the motor is stopped for
some reason. T o restart the motor from this situation, turn
off the power first, fully discharge the pin 6 capacitor next,
and then turn on the power again.

External dimensions (Units: mm)

691