Datasheet BA6407AF Datasheet (ROHM)

Motor driver ICs

2-phase half-wave motor driver

BA6407AF

The BA6407AF is a motor driver dedicated to 12V fan motors. Built-in output transistors reduce the number of external
components required. The IC has a lock signal output pin.

Applications
Fan motors

Features

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

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

Absolute maximum ratings (Ta = 25C)

3) Automatic restart when the motor lock is undone.

Recommended operating conditions (Ta = 25C)

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Motor driver ICs BA6407AF

Block diagram

Pin descriptions

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Motor driver ICs BA6407AF

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

FLock detection

The automatic restart circuit detects a motor lock condi­tion and automatically turns off the output current. When
the lock condition is cleared, the IC automatically restarts
and allow the motor to run.
In the BA6407AF, automatic restart is performed as fol­lows.
A motor lock condition is detected when the Hall signal
stops switching.
The output is ON when the LD pin is being charged, and
OFF when the pin is being discharged.

S The AL pin is ON during normal operation, and OFF

when the motor is locked.

S The AL pin is an open collector output.

Output ON time (T

ON) and OFF time (TOFF) determined by

the LD capacitor

LDCLVLDCP)

TON (Charge time)=

TOFF (Discharge time)=

where

C S (V

C S (V

ILDC

LDCLVLDCP)

ILDD

(Typical value)

C is the capacitance of the LD-pin external capacitor,

LDCL is the LD-pin clamp voltage (2.48V),

V

LDCP is the LD-pin comparator voltage (0.99V),

V

LDC is the LD-pin charge current (3.4µA),

I

LDC is the LD-pin discharge current (0.79µA).

I

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Motor driver ICs BA6407AF

Application example

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Motor driver ICs BA6407AF

Operation notes
(1) Thermal shutdown circuit
The IC has a built-in thermal shutdown circuit. There is
a temperature difference of 25C (typical) between the
temperatures at which the circuit is activated and deacti­vated.

Fig.3

(2) Power dissipation
Power consumed in the IC can be calculated from the fol­lowing equation :

P

C=PC1)PC2)PC3

PC1 is power consumed by the supply current.

C1=VCC ICC

P

PC2 is the output current consumption.

C2=VOL IO

P
VOL is the LOW level voltage of output pins 1 and 2.
P

C3 is power consumed by the AL pin.

C3=VALL IAL

P
where VALL is the AL-pin LOW level voltage and IAL is the
AL-pin sink current. Make sure that your application does
not exceed the allowable power dissipation of the IC.

(3) Hall amplifier input voltage

The Hall current is given by:

where R

The R

H is the hall device impedance.

1 and R2 resistances must be set so as to maintain

VCC

R1)R2)RH

the Hall amplifier input bias voltage within the range of 1V

CC*2V) including the signal amplitude. It is recom-

to (V
mended that the same value be used for both resistors
so that the Hall device output signal is centered around
V

CC /2.

The Hall device may be affected by power supply noise
due to the PCB conductor pattern. If you have this prob­lem, insert a capacitor C

1 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 C

2 as shown in Fig. 5. Note

that the Hall inputs have no hysteresis in this IC.

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Motor driver ICs BA6407AF

Electrical characteristic curves

External dimensions (Units: mm)

705