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Motor driver ICs
Fan motor driver IC
BA6817F / BA6818FS
The BA6817F and BA6818FS are 24V motor drivers for 2-phase, half-wave fan motors. The ICs have lock detection
and automatic restart functions. In compact SOP8 (BA6817F) and SSOP-A16 (BA6818FS) packages, the ICs reduce
the number of external components required.
Applications
2-phase motors such as fan motors
Features
1) Built-in power transistors.
2) Lock detection and automatic restart functions.
3) Thermal shutdown circuit.
Absolute maximum ratings (Ta = 25C)
4) Alarm output pin. (BA6817F / BA6818FS)
5) Hall signal output pin. (BA6818FS)
Recommended operating conditions (Ta = 25C)
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Motor driver ICs BA6817F / BA6818FS
Block diagram
Pin descriptions
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Motor driver ICs BA6817F / BA6818FS
Hall input / output truth table
Input / output circuits
Electrical characteristics (unless otherwise noted, Ta = 25C)
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Motor driver ICs BA6817F / BA6818FS
FCircuit operation
The BA6817F and BA6818FS 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 :
S (VLDCLVLDCP)
ton (Charge time)=
toff (Discharge time)=
C
S (VLDCLVLDCP)
C
I
LDC
ILDD
The timing chart for a motor lock occasion is shown in Fig. 1.
where
V
LDCL is the LD-pin clamp voltage (2.45V),
LDCP is the LD-pin comparator voltage (1.05V),
V
LDC is the LD-pin charge current (2.64µA),
I
LDD is the LD-pin discharge current (0.48µA),
I
C is the capacitance of the LD-pin external capacitor.
For C=0.47µF, for example, the charge (output ON) and
discharge (output OFF) times are 0.24s and 1.37s, respectively.
(Typical value)
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Motor driver ICs BA6817F / BA6818FS
Application example
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Motor driver ICs BA6817F / BA6818FS
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 both output transistors are turned OFF.
Normal operation resumes when the circuit is deactivated.
(2) Power dissipation
Power consumed in the IC can be calculated from the following equation :
P
C=PC1)PC2)PC3
P
C1 is power consumed by the circuit current.
C1=VCZ ICC
P
PC2 is the output stage current consumption.
C2=VOL IO
P
VOL is the LOW level output voltage of output pins 1 and
O is the sink current of pins 1 and 2.
2, and I
P
C3 is power consumed by the AL and HO pins.
(The HO-pin is only for BA6818FS)
where
C3=VALL IAL)VHOL IHO /2
P
ALL is the AL-pin LOW level voltage,
V
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.
(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
to (V
CZ*2V) 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.
V
Hall current is given by :
CZ
R1)R2)RH
where RH is the Hall device impedance.
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Motor driver ICs BA6817F / BA6818FS
External dimensions (Units: mm)
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