As the automotive industry shifts towards smarter and more electric vehicles, the electronic systems in automotive components have become increasingly complex and precise. From engine control units to in-car entertainment systems, from autonomous driving sensors to battery management modules, every component relies on stable voltage supply. However, during vehicle operation, issues such as surge voltage during startup, electromagnetic interference, and electrostatic discharge pose a constant threat to the safety of these electronic systems. The SMAJ13A transient voltage suppression diode, with its precise performance parameters and outstanding over-voltage protection capabilities, has become a reliable safeguard for the stable operation of automotive components.

Slkor Transient Protection Diode SMAJ13A product photo

1. Voltage Challenges Faced by Automotive Components

The automotive operating environment is complex and ever-changing, and electronic systems face various voltage threats. During vehicle startup, the battery can generate surge voltages of up to tens of volts. When the engine ignition system is activated, it emits strong electromagnetic interference. When driving in dry conditions, electrostatic discharge generated from the friction between the vehicle body and air can also trigger instant over-voltage. If these transient over-voltage events are not suppressed in time, they can lead to data errors in automotive electronic control units (ECUs), sensor signal distortion, and even direct damage to core electronic components. For example, if the engine ECU is damaged by over-voltage, it can lead to abnormal engine power output, increased fuel consumption, and in severe cases, vehicle malfunction. Therefore, equipping automotive components with efficient over-voltage protection devices is crucial for ensuring the safe and reliable operation of vehicles.

Slkor Transient Protection Diode SMAJ13A specification

2. Performance Parameters of the SMAJ13A

The performance parameters of the SMAJ13A perfectly match the stringent requirements for over-voltage protection in automotive components. Its reverse working voltage (Vrwm) is 13V, meaning that when the normal operating voltage of the automotive electronic system is below 13V, the diode remains in a high impedance state and has little impact on the normal operation of the circuit, ensuring that automotive electronic devices operate within stable voltage ranges. When the circuit voltage exceeds 14.4V (the minimum breakdown voltage), the SMAJ13A quickly enters breakdown mode, starts conducting, and releases the excess energy. The maximum breakdown voltage limit of 15.9V ensures that the diode works stably and reliably under various conditions, preventing premature breakdown or failure of protection.

Furthermore, the reverse leakage current (Ir) of the SMAJ13A is just 5μA, making it highly effective in preventing interference with weak signals in complex automotive electronic circuits. Whether it's sensor signal transmission in the engine control unit or data transmission in the in-vehicle communication system, the SMAJ13A ensures signal purity. With its maximum clamping voltage of 21.5V, the diode provides a solid [敏感词] for automotive electronic components. Even under high-intensity transient over-voltage surges, the SMAJ13A can respond in an extremely short period, clamping the over-voltage to below 21.5V and effectively reducing the risk of damage to automotive electronics due to over-voltage.

3. Specific Applications of SMAJ13A in Automotive Components

(1) Engine Control Systems  

The engine control system is a core component of a vehicle, with its ECU responsible for precisely controlling critical parameters like fuel injection and ignition timing. The system operates in harsh conditions, enduring vibrations from engine operation and high voltage surges and electromagnetic interference during startup. By installing the SMAJ13A at the ECU’s power input and sensor signal lines, over-voltage can be effectively suppressed. When the vehicle starts, the SMAJ13A quickly conducts, clamping the surge voltage within a safe range, protecting the ECU’s microprocessor and memory chips. During engine ignition, it can also protect against electromagnetic interference, ensuring accurate sensor signal transmission and maintaining optimal engine performance.

(2) In-Car Entertainment and Information Systems  

With the development of smart cabin technology, in-car entertainment and information systems integrate numerous electronic devices such as large-screen displays, multimedia players, and in-car networking modules. These devices have high voltage stability requirements, as over-voltage can lead to screen artifacts or system crashes. When applied in the power circuits and data transmission lines of the in-car entertainment system, the SMAJ13A effectively protects against electrostatic discharge and power surges. For example, when passengers enter or exit the vehicle and generate static electricity, the SMAJ13A quickly releases the static energy, preventing damage to the system. Additionally, when vehicle power voltage fluctuates, the diode stabilizes the voltage at a safe level, ensuring stable operation of the entertainment system and providing a superior user experience.

(3) Autonomous Driving Sensor Systems  

The development of autonomous driving technology relies on the collaboration of multiple sensors, including LiDAR, cameras, and millimeter-wave radar. These sensors require highly accurate and stable signal transmission, as over-voltage can distort sensor output signals and affect the autonomous driving system’s decision-making. Installing the SMAJ13A on the power and signal lines of the sensors effectively suppresses electromagnetic interference and transient over-voltage. While driving in complex electromagnetic environments, the SMAJ13A ensures the sensor signals remain unaffected, providing accurate data to the autonomous driving system and ensuring driving safety.

(4) Battery Management System (BMS)  

The battery management system (BMS) of electric vehicles monitors battery status, balances battery voltage, and performs other critical functions. Its stability directly impacts the vehicle’s range and safety. During operation, the BMS is subject to voltage fluctuations from the battery’s charging and discharging processes, as well as external electromagnetic interference. The SMAJ13A, when applied to the BMS’s power circuits and communication lines, effectively suppresses over-voltage, protecting the control chips and sampling circuits of the BMS. When a voltage surge occurs during battery charging, the SMAJ13A quickly activates, clamping the voltage within a safe range, preventing over-voltage damage to the BMS, and ensuring the safe and stable operation of the power battery.

4. Conclusion

In the electronic systems of automotive components, the SMAJ13A transient voltage suppression diode, with its precise performance and reliable protection capabilities, plays a crucial role in ensuring the safety and stability of vehicles. From engine control systems to autonomous driving sensors, from in-car entertainment systems to battery management systems, the SMAJ13A serves an irreplaceable role across various key areas. As automotive technology continues to advance, the demand for electronic component reliability will only increase. The SMAJ13A will continue to support the development of the automotive industry, helping automotive components achieve higher levels of performance and safety.

About Slkor：

Slkor has research and development offices in Busan, South Korea, Beijing, China, and Suzhou, China. Most of the wafer manufacturing and packaging and testing are carried out within China. The company employs and collaborates with individuals and organizations worldwide, with a laboratory for product performance and reliability testing and a central warehouse located at its headquarters in Shenzhen. Slkor has filed for over a hundred invention patents, offers more than 2,000 product models, and serves over ten thousand customers globally. Its products are exported to countries and regions including Europe, the Americas, Southeast Asia, and the Middle East, making it one of the rapidly growing semiconductor companies in recent years. With well-established management systems and streamlined workflows, Slkor has rapidly enhanced the brand awareness and reputation of its "SLKOR" brand through its outstanding quality and standardized services. Its product range includes three major series: diodes, transistors, and power devices, with recent introductions of new products such as Hall elements and analog devices, expanding its presence in sensors, Risc-v microcontrollers, and other product categories.