DIRECT DRIVING EXTERNAL POWER DARLINGTON COIL CURRENT CHARGING ANGLE (

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DIRECT DRIVING EXTERNAL POWER DARLINGTON COIL CURRENT CHARGING ANGLE (

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HALL EFFECT PICKUP IGNITION CONTROLLER
DIRECT DRIVING EXTERNAL POWER DARLINGTON COIL CURRENT CHARGING ANGLE (dwell) CONTROL PROGRAMME COIL CURRENT PEAK LIMITATION PROGRAMMABLE DWELL RECOVERY TIME WHEN NOMINAL CURRENT REACHED OUTPUT PERMANENT CONDUCTION PROTECTION OVERVOLTAGE PROTECTION EXTERNAL DARLINGTON INTERNAL SUPPLY ZENER REVERSE BATTERY PROTECTION
DIP16
SO16
ORDERING NUMBERS L497B (DIP16) L497D1 (SO16)
DESCRIPTION L497is integratedelectronicignition controller breakerless ignition systemsusing Hall effect sensors. BLOCK DIAGRAM
device drives external darlington control coil current providingthe required stored energy with dissipation. special feature L497 programmable time recovery correct dwell ratio Td/T when coil peak current fails reach nominal value. this only spark have energy less than nominal during fast acceleration cold starts.
March 1998
1/11
ABSOLUTE MAXIMUM RATINGS
Symbol Parameter D.C. Supply current Transient Supply Current fall time constant 100ms) Supply Voltage Voltage D.C. Driver Collector Current Pulse 3ms) Driver Collector Voltage Auxiliary Zener Current D.C. Overvoltage Zener Current Pulse fall 300µs, trep Repetition Time Reverse Battery Voltage Application Circuit Fig. used Junction StorageTemperature Range Power Dissipation Taluminia SO-16 Tamb DIP-16 Value Int. Limited 0.65 Unit
Tstg Ptot
CONNECTION (top view)
THERMAL DATA
Symbol Parameter Value Unit °C/W °C/W
Thermal Resistance Junction-ambient DIP-16 j-amb j-alumin Thermal Resistance Junction-alumina SO-16
Thermal resistance junction-aluminia device soldered ddle aluminia supporting substrate mesuri 0.65 thickness.
2/11
FUNCTIONS (refer fig.
Name SIGNAL POWER SUPPLY Function This must connected ground. This must connected ground. Supply Voltage Input. internal (typ) zener zener limits voltage this pin. external resistor limits current through zener high supply voltages. This must connected ground left open. Hall-effect Pickup Signal Input. This input dwell control circuit output order enable current driving into coil. spark occurs high-to-low transition hall-effect pickup signal. Furthermore this input signal enables slow recovery permanent conduction protection circuits. input signal, supplied open collector output stage Hall effect sensor, duty-cycle typically about internally clamped ground diodes Open collector output which level when current flows ignition coil. high voltages protection this output, connection zener recommended. this situation must limit zener current, too, limits current module accidentally connected (typ) General Purpose Zener. current must limited external resistor. capacitor connected between this ground sets slope dwell time variation rises from zero correct value. This occurs after detection Icoll Inom, just before transition hall-effect signal pulse. duration slow recovery given tsrc 12,9 Csrc (ms) where biasing resistor Csrc delay capacitor µF). capacitor connected between this ground determines intervention delay permanent conduction protection. After this delay time coil current slowly reduced zero. Delay Time given (ms) where biasing resistor delay capacitor µF). capacitor connected between this ground charged when HAll effect output High discharged High transition Hall effect signal. recommended value using resistor average voltage capacitor connected between this ground depends motor speed voltage supply. comparison between voltage determines timing dwell control. optimized operation device recommended value using resistor resistor connected between this ground sets internal current used drive external capacitors dwell control (pin permanent conduction protection (pin slow recovery time (pin recommended value Connection Coil Current Limitation. current measured sensing resitor taken through divider 10/R current limitation value given Isens 0.32 3/11
N.C. HALL-EFFECT INPUT
OUTPUT
AUX. ZENER RECOVERY TIME
CONDUCTION TIME
DWELL CONTROL TIMER
DWELL CONTROL
BIAS CURRENT
CURRENT SENSING
FUNCTIONS (continued)
Name DRIVER EMITTER OUTPUT Function Current Driver External Darlington. ensure stability precision Tdesat must used. Recommended value order change open loop gain system. added obtain greater flexibility various application situations. values ranges depending external darlington type. darlington protected against overvoltage means internal zener available this connected internal divider R3/R defines limitation value given
OVERVOLTAGE LIMIT
22.5 5.10-3 22.5 Vovp
DRIVER COLLECTOR INPUT collector current internal driver which drives external darlington supplied through this pin. Then external resistor limits maximum current supplied base external darlington.
ELECTRICAL CHARACTERISTICS 14.4 unless otherwise specified)
Symbol V16-14 VSENS I11C Parameter Voltage Supply Current Voltage Supply Supply Clamping Zener Voltage Input Voltage Input Current Darlington Driver Sat. Current Current Limit. Sensing Voltage Charge Current Status High Status 0.5V 33ms 0.5V 33ms 0.5V 33ms Percentage Output Current Determining Slow Recovery Control Start (fig. note Duration Altered Small Contr. CSRC Ratio after Function Start (fig. External Darlington over Prot. Zener Voltage Permanent Conduction Time High 11.0 Test Conditions Min. Typ. Max. Unit
I11D
Charge Current
I11C I11D
Note
22.0
ISRC ISENSE TSRC
98.5
VZ15
22.5 21.5
4/11
ELECTRICAL CHARACTERISTICS (continued)
Symbol 6SAT leak
otes
Parameter Output Saturation Voltage Output Leakage Current Auxiliary Zener Voltage Reference Voltage
td/t desaturation ratio given
Test Conditions 18.5
Min.
Typ.
Max.
Unit
1.20 1.25
1.30
I11C I11D Isense Icoil when external Darlington active region.
APPLICATION INFORMATION Figure Main Waveforms.
5/11
DWELL ANGLE CONTROL dwell angle control circuit calculates conduction time output transistor relation speed rotation, supply voltage characteristics coil. negative edge Hall-effect input signal capacitorCW beginsdischargingwith constant current l11D. Whenthe peak value coil current reached, this capacitor charges with constant current I11C 13.3 I11D, coil current kept constant desaturationof driven stage external darlington. capacitor starts charging positive.edge Hall-effect input signal with constant current I10C. dwell angle, consequentlythe starting point coil current conduction, decided comparison between V11. positive hysteresis added dwell comparator avoid spurious effects rapidly discharged negative edge Hall-effects input signal. this average voltage increases motor speed decreases viceversa order maintainconstantthe ratio motor speed. kept constant (and cost) control power dissipation have sufficient time avoid energy sparks during acceleration. DESATURATION TIMES STATIC CONDITIONS static conditions recommended values applicationcircuit fig.4 used. I11C I11D TRANSIENT RESPONSE ignition system must deliver constant energy even duringthe conditionof accelerationand decelerationof motor below80Hz/s.Theseconditions simulated means signal gene-rator with linearly modulated frequency between (this corresponds change between 6000 cylinders engine). CURRENT LIMIT currentin thecoil monitoredby measuringthe Isense current flowing sensing resistor emitter external darlington. Isense given sense Icoi When voltage drop across reaches internal comparator thresholdvalue feedbackloop activated Isense kept constant (fig.1) forcing external darlington active region. this condition sense coil Whena precisepeak coil currentis requiredRs must trimmed auxiliary resistor divider (R10, R11) added 0.320 eak(A) SLOW RECOVERY CONTROL (fig. Isense reached nominal value just before negativeedge Hall-effect input signal, capacitor Csrc quickly dischargedas long pick-up signalis "low". next positive transition input signal load current starts immediately, producingthe maximum achievable Tdesat; then voltage CSRC increases linearly until standby reached.During this recoverytime CSRC voltageis convertedinto current which, substrated from charging current dwell capacitor, produces Tdesat modulation. This means that Tdesat decreases slowly until valuereaches,after time TSRC, thenominal value. time TSRC given Trsc 12.9 CSRC (ms) where isthe biasing resistor Csrc capacitor µF).
DESATURATION TIMES HIGH FREQUENCY OPERATION upperlimit voltagerange components fig.4 used, below (300 cylinder engine) time reachesits maximum value (about then circuit gradually loses control dwell angle because Over (6000 cylinderengine) availabletime conductionis less than used coil time reduced zero circuit loses dwell angle control.
6/11
Figure Icoil Failure Time Dependence Active Region.
Input signal Coil current
Voltage capacitor CSRC. Percentage imposed desaturation time.
Figure Permanent Conduction Protection.
PERMANENT CONDUCTION PROTECTION (fig. permanent conduction protection circuit monitors input period, chargingCP with costantcurrent when sensor signal high discharging when sensor signal low. input remains high time longer than voltage across reachesan internallyfixed valueforcingthe slow decrease coil current zero. slow decrease
necessary avoid undesired sparks. When input signal goes again swiftly discharged current control loop operates normally. delay time given (sec) Where biasing resistor delay capacitor µF).
7/11
OTHER APPLICATION NOTES DUMP PROTECTION Load dump protection must implemented external zener this function necessary. fig. protects driver stage, connection between protects output transistor MoreoverDZ1 protectsboth power supply input (pin Hall-effect sensor. Resistor necessary limit current during load dump. OVERVOLTAGE LIMITATION external darlington collector voltage sensed voltage divider voltage limitation increases rising decreasing active circuit used, series network mandatory stability during high voltage condition. values depend darlington used application. Moreover resistor suggested limit overvoltage even when supply voltage disconnected during high voltage condition. REVERSE BATTERY PROTECTION presenceof externalimpedanceat L497 protected against reverse battery voltage. NEGATIVE SPIKE PROTECTION correct operation requested also during short negativespikes,the diode capacitorCs must used.
Figure Application Circuit.
8/11
DIP16 PACKAGE MECHANICAL DATA
DIM. MIN. 1.27 2.54 17.78 0.130 0.050 0.51 0.77 0.25 0.335 0.100 0.700 0.280 0.201 1.65 TYP. MAX. MIN. 0.020 0.030 0.020 0.010 0.787 0.065 inch TYP. MAX.
9/11
SO16 PACKAGE MECHANICAL DATA
DIM. MIN. 1.27 8.89 1.27 0.62 (max.) 0.150 0.020 0.35 0.19 (typ.) 0.386 0.228 0.050 0.350 0.157 0.050 0.024 0.394 0.244 TYP. MAX. 1.75 0.46 0.25 0.014 0.007 0.020 0.004 MIN. inch TYP. MAX. 0.069 0.008 0.063 0.018 0.010
10/11
Information furnished believed accurate reliable. However, SGS-THOMSON Microelectronics assumes responsibility consequences such information infringement patents other rights third parties which result from use. license granted implication otherwise under patent patent rights SGS-THOMSON Microelectronics. Specification mentioned this publication subject change without notice. This publication supersedes replaces information previously supplied. SGS-THOMSON Microelectronics products authorized critical components life support devices systems without express written approval SGS-THOMSON Microelectronics. 1998 SGS-THOMSON Microelectronics Printed Italy Rights Reserved SGS-THOMSON Microelectronics GROUP COMPANIES Australia Brazil Canada China France Germany Italy Japan Korea Malaysia Malta Morocco Netherlands Singapore Spain Sweden Switzerland Taiwan Thailand United Kingdom U.S.A.
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DIRECT DRIVING EXTERNAL POWER DARLINGTON COIL CURRENT CHARGING ANGLE (

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