L497

L497 HALL EFFECT PICKUP IGNITION CONTROLLER . . . . . . . . . DIRECT DRIVING OF THE EXTERNAL POWER DARLINGTON COIL CURRENT CHARGING ANGLE (dwell) CONTROL PROGRAMME COIL CURRENT PEAK LIMITATION PROGRAMMABLE DWELL RECOVERY TIME WHEN 94 % NOMINAL CURRENT NOT REACHED RPM OUTPUT PERMANENT CONDUCTION PROTECTION OVERVOLTAGE PROTECTION FOR EXTERNAL DARLINGTON INTERNAL SUPPLY ZENER REVERSE BATTERY PROTECTION DIP16 SO16 ORDERING NUMBERS : L497B (DIP16) L497D1 (SO16) DESCRIPTION The L497is an integratedelectronicignition controller 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 Td/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 L497 ABSOLUTE MAXIMUM RATINGS Symbol I3 V3 V6 I16 V16 I7 I15 Parameter D.C. Supply current Transient Supply Current (tf fall time constant = 100ms) Supply Voltage RPM Voltage D.C. Driver Collector Current Pulse ” ”(t <= 3ms) Driver Collector Voltage Auxiliary Zener Current D.C. Overvoltage Zener Current Pulse ” ” t fall = 300µs, trep Repetition Time > = 3ms Reverse Battery Voltage if Application Circuit of Fig. 4 is used Junction and StorageTemp...