The electronic ignition switch 98.3734 the development and production of JSC "CNPP "ELARA" (hereinafter - the switch is designed for switching the current in the primary the winding of the coil of the contactless ignition system of automobiles families VAZ-2105, VAZ-2108, VAZ-2110, VAZ-21213, VAZ-1111, ZAZ-1102 [1]. The device is protected the utility model certificate.
The device works in conjunction with the ignition coils 3122.3705, and their 27.3705 modifications with the impedance of the primary winding is less than 0.7 Ohms and the inductance of not more than 7 mH, sensor-dispenser 40.3706, and their 3810.3706 the modifications. Nominal voltage - 12, maximum is 16, the minimum is 6 V. the limitations of current through the ignition coil switch normalizes depending on the operation mode in the range from 0.6 to 4.5 MS, which is 2… 15% of the duration of the period of the input signal at a frequency of 33 Hz and the supply voltage of 13,5 V. the Switching current of the ignition coil (current gap) limited switch at 7.3…of 7.8 And at a voltage of 13.5 V. The switch stops the flow of current through the ignition coil 1 with after stop shaft sensor-way valve, preventing sparking. Working the interval of the ambient temperature from -45 to +105 °C.
The switch scheme it is shown in Fig. 1, and the exterior in Fig. 2.
Reference designators all elements match the schema of the manufacturer. The basis of the device - specialized integrated chip L497D by ST Microelectronics, designed to control a switching transistor part no bu941zp the same firm. The operation of the chip is described in detail in [2]. Let us consider some features of its work with than typical circuit is turned on.
DA1 chip is powered by two current sources. The first source transistors VT1 and VT2 provides a current of 50 mA for supply of the Hall sensor and circuits DA1. It the output current depends on the resistance of the resistor R3 and the voltage on the emitter the transition of the transistor VT1. Resistor R2 sets the operating point of the transistor VT2 and the voltage at the collector of the transistor VT1.
In the case of increasing temperature, the voltage at the resistor R3 decreases approximately $ 2.1 mV/°C, which leads to a corresponding decrease in the output current. Capacitor C9 suppresses the high frequency oscillations which may occur during the the appearance of the emission voltage in the vehicle electrical system.
A second current source, transistors VT3 and VT4, stabilizes the base current of the transistor VT5 at 40 mA. The use of transistors MJE350 (VT2, VT4) in the current sources provides reliable operation of the switch in case the occurrence of impulse noise voltage up to 350 In the on-Board network of the vehicle and increasing the ambient temperature to 105 °C.
The Zener diode VD3 BZX84C9V1 stabilizes voltage 9 V to power the Hall sensor.
Diode VD1 protects your device against polarity reversal power source.
Resistor R28 and diode Assembly VD5 provide reliable protection of the input circuits from possible surges.
Chain VD4R13C8R14 protects the transistor VT5 in the case of increasing the voltage in the on-Board network. If the voltage exceeds 24, the Zener diode VD4 and through resistors R13, R14 current begins to flow, resulting in increased voltage at the input HI (pin 13) current feedback circuits DA1 and to reduce the level limit the current in the ignition coil. When the voltage exceeds about 70 In the switch is fully turned off.
The current sensor switching transistor (R18-R27) is made of ten parallel included resistors for surface mount a resistance of 1 Ohm. In earlier unreleased switches the function of the current sensor performed resistor ASKA a resistance of 0.1 Ohms ±5 %. However, the experiments showed that the use here the sensor has better temperature stability.
In block applied import element base mainly for surface installation. Fixed resistors and ceramic capacitors X7R size 1206. Bipolar transistors BUZ941ZP and MJE350 interchangeable transistors CTA (or series CT, CT, CTD) and CTA respectively, and the transistors VS - VS.
Literature
Author: Andrei Pozdeev, Cheboksary