BA6427F ROHM Co. Ltd., BA6427F Datasheet - Page 4

• Manufacturer Part Number: BA6427F
• Description: Single-phase Full-wave Motor Driver
• Manufacturer: ROHM Co. Ltd.

FLock detection
The automatic restart circuit detects a motor lock condi-
tion and automatically turns off the output power. When
the lock condition is cleared, the IC automatically restarts
and allow the motor to run.
In the BA6427F, automatic restart is performed as fol-
lows.
A motor lock condition is detected when the Hall signal
stops switching. The output is OFF when the LD pin is be-
ing charged.
(1)
Hall signal.
(2)
The time required for the external capacitor at the LD pin
to charge or discharge when the motor is locked varies
with the capacitor size. The charge and discharge times
are obtained by:
C is the capacitance of the external capacitor connected
to the LD pin,
V
V
I
I
For C = 0.47 F, for example, the charge and discharge
times are 0.19 s (output ON) and 1.15 s (output OFF),
respectively.
The timing of the LD pin is shown in Fig.1.
766
LDC
LDD
Motor driver ICs
LDCL
LDCP
T
T
is the LD pin discharge current
is the LD pin charge current
ON
OFF
The HO pin outputs a signal synchronized with the
The HO pin is an open collector output.
is the LD pin clamp voltage
is the LD pin comparator voltage
(charge time) =
(discharge time) =
C (V
LDCL
C (V
I
LDC
– V
LDCL
LDCP
I
LDD
– V
(0.48 A Typ.).
)
(1.93V Typ.),
(0.76V Typ.),
(2.9 A Typ.),
LDCP
)
FOperation notes
(1)
The IC has a built-in thermal shutdown circuit. There is
a degree of hysteresis in the TSD circuit.
The circuit is activated at the temperature of about 175_C
(typical), so that all outputs are turned OFF. The circuit is
deactivated when the temperature drops to about
150_C, and normal operation resumes. (With the typical
values, there is a hysteresis of 25_C.)
(2)
The power dissipated by the IC varies widely with the
supply voltage and the output current. Make sure that
your application does not exceed the allowable power
dissipation of the IC package.
(3)
(1) The values of the Hall device bias resistors (see the
block diagram) must be set so as to maintain the Hall am-
plifier input bias voltage within the range of 0V to V
including the signal amplitude. It is recommended that
the same value be used for both resistors so that the Hall
device output signal centered around V
the IC.
(2) Be careful of the input signal for the Hall inputs of this
IC have no hysteresis.
(4)
Make sure that the output current will not exceed the ab-
solute maximum rating or the ASO value.
(5)
Be sure to keep the GND potential lower than the poten-
tials of the other pins.
Thermal shutdown circuit
Current consumption
Hall input pins (H
ASO
Ground pin potential
)
, H
*
)
CC
BA6427F
/ 2 is input to
CC
-2V,