L497
HALL EFFECT PICKUP IGNITION CONTROLLER
.
.
.
.
.
.
.
.
.
DIRECT DRIVING OF THE EXTERNAL
POWER DARLINGTON
COIL CURRENT CHARGING ANGLE (dwell)
CONTROL
PROGRAMME COIL CURRENT PEAK LIMITA-
TION
PROGRAMMABLE DWELL RECOVERY TIME
WHEN 94 % NOMINAL CURRENT NOT
REACHED
RPM OUTPUT
PERMANENT CONDUCTION PROTECTION
OVERVOLTAGE PROTECTION FOR EXTER-
NAL DARLINGTON
INTERNAL SUPPLY ZENER
REVERSE BATTERY PROTECTION
DIP16
SO16
ORDERING NUMBERS :
L497B (DIP16)
L497D1 (SO16)
DESCRIPTION
The L497is an integratedelectronicignition control-
ler for breakerless ignition systemsusing Hall effect
sensors.
BLOCK DIAGRAM
The device drives an NPN external darlington to
control the coil current providingthe required stored
energy with low dissipation.
A special feature of the L497 is the programmable
time for the recovery of the correct dwell ratio T
d
/T
when the coil peak current fails to reach 94 % of the
nominal value. In this way only one spark may have
an energy less than 94 % of the nominal one during
fast acceleration or cold starts.
March 1998
1/11