Characteristics of automotive electronic circuits

Automotive electronic circuits refer to circuits that combine electronic components such as semiconductor discrete devices, integrated circuits and microprocessors with automobiles to complete a certain control function.

Although automotive electronic circuits are also composed of electronic components and have the characteristics of ordinary electronic circuits, they also have their own particularities, which can be summarized into the following aspects.

1. Close integration of mechatronics

When automotive electronic technology is applied to actual circuits, it is often combined with some related mechanical systems on the car to complete a certain function. The electronic circuit usually processes the received detection signal, and then issues relevant control instructions based on the detected signal, and the related switches such as relays control the execution system (or mechanism) to complete a certain function. The execution system (or mechanism) here is composed of mechanical systems.

For example, the electronic ignition control circuit of an automobile receives the detected signal sent by the ignition signal sensor, and after processing, it issues a control command to interrupt the primary current of the ignition coil. The high voltage electricity generated by its secondary coil is distributed to the spark plugs of each cylinder by the distributor according to the ignition sequence, so that the high voltage electric spark generated by the spark plug ignites the combustible mixture. The electronic ignition control circuit here provides the control signal, and the actuator mechanical system is the distributor.

2. Used in automobiles as components

Due to the restrictions of special working conditions (field operations, harsh environmental conditions, etc.), the vibration and impact of the car when driving on different levels of roads are large; at the same time, the temperature of the engine when working is high (T>60℃). If certain measures are not taken, the electronic circuits working in this environment will often be damaged early or unstable. Secondly, water in the electronic circuit will cause a short circuit between the circuits. Therefore, the electronic circuits on the car are mostly used in the form of components, and the components are sealed and installed in a well-ventilated place, such as the electronic voltage regulator in the charging system, the electronic igniter in the ignition system, the ECU (abbreviation of Electronics Control Unit in English, which means electronic control unit, or electronic controller, or electronic control device in Chinese) components in the electronic fuel injection control system, and the ABS (abbreviation of Anti Lock Braking System in English, which means anti-lock braking system) components.

3. To complete a certain control function

The electronic circuits used in automobiles, except for a very small number of components composed of large-scale integrated microprocessors that have multiple control functions, most are used to complete a certain control function, so the circuits are relatively simple.

4. There are many types of components used

The electronic components used in automotive electronic circuits include commonly used transistors, crystal diodes, resistors and capacitors, as well as special or general integrated circuits, such as 555 timing circuits and L497 ignition integrated circuits, and large-scale microprocessor integrated circuits, such as engine electronic control unit ECU, ABSECU (anti-lock braking electronic control unit microprocessor), CCSECU (cruise electronic control microprocessor), SRSECU (airbag electronic control microprocessor), ECTECU (electronically controlled automatic transmission microprocessor), etc.

Among the composed (unit) electronic circuits, there are all-discrete components, circuits composed of integrated circuits, and hybrid electronic circuits that combine discrete components and integrated circuits.

In order to reduce the size, some components used in automotive electronic appliances are installed in sheet form, such as sheet integrated circuits, sheet resistors, sheet capacitors, sheet transistors, etc.