FAN8412M/FAN8413M
6
Application Information
1. Lock Detection & Automatic Restart
FAN8412M/FAN8413M features a lock detection and an automatic restart. The functions can be operated as follows.
When the rotor is locked, there is no change in input signal of hall amplifier.
A capacitor(C
LD
) connected LD pin is continually charged by internal current source (I
LDC
) to intrrnal threshold(V
LDCL
).
When the voltage, V
CLD
on LD pin, reaches V
LDCL
, output power TR is turned-off to protect motor during T
OFF
and
alarmoutput(AL) becomes floating high and taco output(TACO) becomes remain high or low. When the V
CLD
reaches upper
threshold,V
LDCL
,V
CLD
starts to decrease with internal current sink(I
LDD
) to the low threshold,V
LDCP
. At that time, the
V
CLD
charging repeat until locked condition is removed, or FAN8412M/FAN8413M is power down.
The auto-restart time (T
ON
), the motor protection time(T
OFF
) are propotional to external capacitor,C
LD
and each value can be
calculated as follow;
For example,C
LD
=1uF, then T
ON
=0.57Sec, T
OFF
=2.2Sec. This AL or TACO output can be used to inform a locked rotor con-
dition or speed information to super IO or system controller. Because the AL or TACO output is open collector type, end user
can pull up this pin with a external resister to the supply voltage of their choice(that is 5 or 3.3V).
T
OFF
T
ON
Hall Input
Output
V
LDCL
V
LDCP
AL
Motor lock
Motor restart
TACO
Motor lock
detected
Motor lock
cleared
T
ON
C
LD
V
LDCL
V
LDCP
–()×
I
LDC
-----------------------------------------------------------------------=
T
OFF
C
LD
V
LDCL
V
LDCP
–()×
I
LDD
-----------------------------------------------------------------------=
