L497 STMicroelectronics, L497 Datasheet - Page 8

• Manufacturer Part Number: L497
• Description: HALL EFFECT PICKUP IGNITION CONTROLLER
• Manufacturer: STMicroelectronics

L497
OTHER APPLICATION NOTES
DUMP PROTECTION
Load dump protection must be implemented by an
external zener if this function is necessary. In fig. 4
DZ
tween pin 6 and 7 protects the output transistor of
pin 6. MoreoverDZ
input (pin 3) and Hall-effect sensor.
Resistor R
load dump.
OVERVOLTAGE LIMITATION
The external darlington collector voltage is sensed
by the voltage divider R
increases rising R
Due to the active circuit used, an R
Figure 4 : Application Circuit.
8/11
2
protects the driver stage, the connection be-
4
is necessary to limit DZ
2
1
or decreasing R
protectsboth the power supply
2
, R
3
. The voltage limitation
1
o
3
.
current during
C
o
series net-
work is mandatory for stability during the high vol-
tage condition.
R
application.
Moreover the resistor R
overvoltage even when supply voltage is discon-
nected during the high voltage condition.
REVERSE BATTERY PROTECTION
Due to the presenceof externalimpedanceat pin 6,
3, 16, 15 L497 is protected against reverse battery
voltage.
NEGATIVE SPIKE PROTECTION
If correct operation is requested also during short
negativespikes,the diode D
be used.
o
C
o
values depend on the darlington used in the
13
is suggested to limit the
S
and capacitorC
s
must