As a key component of modern automobiles, wiring harness consists of thousands of assembly components, which connect various electronic systems together so that they can work together. Any faulty wiring harness may have an impact on the whole system. However, in order to meet the increasing demand for electronic systems in vehicles, the complexity of automotive wiring harness is also increasing. Therefore, it is more urgent for us to quickly and simply detect the open and short circuit lines. Line diagnosis is very important throughout the life of the vehicle. Starting from the installation phase, diagnosing and repairing line faults can lead to serious manufacturing delays. At the operational stage, the diagnosis and repair of line faults may lead to an increase in the number of automobile repairs, thus greatly increasing the maintenance costs of manufacturers.
Active safety systems, including lane detection and parking assistance systems (front-looking and rear-looking cameras), and information entertainment systems (including navigation and back-seat entertainment), are the automotive electronic systems that people pay more attention to. For these systems to operate efficiently, video data transmitted by cable from any corner of the car must be able to be reliably transmitted to drivers and passengers. The health of cables is very important to maintain the normal operation of these systems.
Olite manufacturer put forward a circuit concept, which can provide reliable, economical and efficient technology to diagnose on video and audio transmission lines for automotive applications. The circuit can effectively detect battery short circuit (STB), ground short circuit (STG), open circuit and short circuit faults. The circuit uses ADA4433-1 (U1) fully integrated video reconstruction filter as part of the video transmission signal chain, and uses ADA4830-1 (U2) high-speed differential amplifier as detection circuit. ADA4433-1 has a high-order filter built in. The cut-off frequency of -3 dB is 10 MHz. It provides 45-dB suppression at 27 MHz. It also has a fixed internal gain of 2 V/V. It has excellent video characteristics, provides over-voltage protection (OVP) and over-current protection (STG) on the output, and low power consumption. ADA4830-1 provides a 0.50 V/V attenuation gain and a fault detection output flag indicating whether there is an overvoltage condition on its input. It provides up to 18 V input overvoltage protection, wide input common-mode voltage range and excellent ESD stability.