L497 STMicroelectronics, L497 Datasheet - Page 7

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

Figure 2 : SRC : I
Figure 3 : Permanent Conduction Protection.
PERMANENT CONDUCTION PROTECTION
(fig. 3)
The permanent conduction protection circuit moni-
tors the input period, chargingCP with a costantcur-
rent when the sensor signal is high and discharging
it when the sensor signal is low. If the input remains
high for a time longer than T
reachesan internallyfixed value forcingthe slow de-
crease of coil current to zero. A slow decrease is
H
I
C
J
: Coil current
: Input signal
coil
Failure and Time Dependence of Active Region.
P
the voltage across C
P
V
D
necessary to avoid undesired sparks. When the in-
put signal goes low again C
and the current control loop operates normally.
The delay time T
Where R
Cp the delay capacitor at pin 9 (in F).
CM
ST
: Percentage of imposed desaturation time.
: Voltage on capacitor C
7
is the biasing resistor on pin 12 (in K) and
T
P
P
(sec) = 18 C
is given by :
SRC.
P
is swiftly discharged
P
R
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