Product Attribute:
Applicationt:
Acura, Alfa romeo, Aston martin, audi, Aux, Baolong, Beiqi, Bentley, BMW, Bugatti, Buick, BYD, cadillac, Changan, Changfeng, Chery, chevolet, Chrysler, Citroen, Changhe Auto, Dadi, DAEWOO, Daihatsu, Dodge, Dongfeng, DADI Auto, Geely, GMC, Gonow, Great wall, Hafei, HAMA, Honda, Hongqi, Huandai, Huizhong, Hummer, Hyundai, Huanghai Auto, Infiniti, iveco, Jaguar, Jeep, Jinbei, JMC, JAC, Kia, Lamborghini, Land rover, Landwind, Lexus, Lincoln, Lotus, LIFAN, Maserati, Maybach, Mazda, Mercedes Benz, MG, Mini, Misubishi, Mitsubishi, Monaro, Nissan, OPEL, Pagani, Peugeot, Porsche, Polarsun Automobile, Renault, Rolls Royce, Rowe, SAAB, Shuanghuan, Shuguang, Skoda, Smart, Soueast, Spyker, ssangyong, SUBARU, Suzuki, Shanghai Maple, Tianma, Toyota, Toyota, volkswagen, volvo, VW, Wanfeng, Wuling, Xiali, Ycaco, Zhonghua, Zhongxing, Zotye
Production Description:
Hall Effect Pickup Ignition Control ICs
Description
The LD497 (analog L497) is an integrated electronic ignition controller for breakerless ignition systems using Hall effect sensors. The device drives an NPN external darlington to control the coil current providing the required stored energy with low dissipation. A special feature of the LD497 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 accelerationor cold starts.
Features
Direct driving of the external power darlington
Coil current charging angle(dwell) control
Programme coil current peaklimitation
Programmable dwell recovery time when 94 %
nominal current not reached
RPM Output
Permanent conduction protection
Overvoltage protection for exterrnal darlington
Internal supply zener
Reverse battery protection
Application Information
Dwell Angle Control
The dwell angle control circuit calculates the conduction time D for the output transistor in relation to the speed of rotation, to the supply voltage and to the characteristics of the coil.
On the negative edge of the Hall-effect input signal the capacitor CW begins discharging with a constant current I11D. When the set peak value of the coil current is reached, this capacitor charges with a constant current I11C = 13.3 ×I11D, and the coil current is kept constant by desaturation of the driven stage and the external darlington.
The capacitor CT starts charging on the positive edge of the Hall-effect input signal with a constant current I10C. The dwell angle, and consequently the starting point of the coil current conduction, is decided by the comparison between V10 and V11.
A positive hysteresis is added to the dwell comparator to avoid spurious effects and CT is rapidly discharged on the negative edge of Hall-effects input signal.
In this way the average voltage on CW increases if the motor speed decreases and viceversa in order to maintain constant the ratio td/T at any motor speed. td/T is kept constant (and not D/T=cost) to control the power dissipation and to have sufficient time to avoid low energy sparks during acceleration.Desaturation Times In Low and High Frequency Operation
Due to the upper limit of the voltage range of pin 11, if the components of fig.4 are used, below 10 Hz (300 RPM for a 4 cylinder engine) the OFF time reaches its maximum value (about 50 ms) and then the circuit gradually loses control of the dwell angle because D= T - 50 ms.
Over 200Hz (6000 RPM for a 4 cylinder engine) the available time for the conductionis less than 3.5 ms. If the used coil is 6 mH, 6A, the OFF time is reduced to zero and the circuit loses the dwell angle control.
Transient Ransient Response
The ignition system must deliver constant energy even during the condition of acceleration and deceleration of the motor below 80Hz/s. These conditions can be simulated by means of a signal generator with a linearly modulated frequency between 1Hz and 200Hz (this corresponds to a change between 30 and 6000 RPM for a 4 cylinders engine).Slow Recovery Control (fig. 2)