Introduction

With the rapid development of electronic technology, current sensors have become key components in power electronics systems. Their stability and reliability directly affect the overall performance of the system. In practical applications, current sensors often face threats from transient overvoltages, such as lightning strikes and power surges, which can damage the sensors and even cause system failures. The Transient Voltage Suppression (TVS) diode, as an efficient overvoltage protection device, can effectively absorb and suppress transient overvoltages, thus protecting current sensors from damage. This paper will focus on the application of the SMAJ6.5A transient voltage suppression diode in current sensors.

Slkor Transient Protection Diode SMAJ6.5A product photo

Core Parameter Analysis of SMAJ6.5A

The SMAJ6.5A is a unidirectional TVS transient voltage suppression diode, with the following key parameters: the reverse working voltage (Vrwm) is 6.5V, the breakdown voltage (minimum) is 7.22V, the breakdown voltage (maximum) is 7.98V, the reverse leakage current (Ir) is 500μA, and the maximum clamping voltage is 11.2V. These parameters determine the protection performance of the SMAJ6.5A in current sensors.

Slkor Transient Protection Diode SMAJ6.5A specification

The reverse working voltage of 6.5V indicates that under normal operating voltage, the SMAJ6.5A remains in a high impedance state and does not interfere with the normal operation of the current sensor. When a transient overvoltage occurs in the circuit, the breakdown voltage range of the SMAJ6.5A (7.22V–7.98V) ensures that it will quickly conduct when the overvoltage reaches a certain threshold, clamping the overvoltage to a safe level. The maximum clamping voltage of 11.2V limits the peak of the overvoltage, protecting the sensitive components inside the current sensor from damage. The reverse leakage current of 500μA is very small under normal operating conditions, and its impact on the accuracy of the current sensor is negligible.

Parameters of Slkor Transient Protection Diode SMAJ6.5A

Protection Principle of SMAJ6.5A in Current Sensors

In current sensors, the SMAJ6.5A is usually connected in parallel at the input or output of the sensor. When a transient overvoltage occurs in the circuit, the SMAJ6.5A responds quickly, and its internal PN junction undergoes avalanche breakdown under reverse bias, forming a low-impedance path to dissipate the overvoltage energy. At the same time, the clamping action of the SMAJ6.5A limits the overvoltage to below the maximum clamping voltage of 11.2V, thereby protecting the core components of the current sensor, such as Hall elements and magnetoresistive elements, from damage due to overvoltage.

Practical Engineering Application Example

For instance, in an industrial automation control system, the current sensor frequently faces transient overvoltages due to lightning induction and power switching. To protect the current sensor, engineers connected the SMAJ6.5A transient voltage suppression diode in parallel at the input of the sensor. During actual operation, the system encountered multiple lightning strikes and power surge impacts, but the current sensor continued to function normally without any damage. A comparison of the system’s failure rate before and after installing the SMAJ6.5A revealed a significant reduction in failures after installation, greatly enhancing the reliability and stability of the equipment.

Comparison of SMAJ6.5A with Other Protection Devices

Compared with traditional varistors, the SMAJ6.5A has advantages such as faster response time, precise clamping voltage, and low leakage current. Varistors are relatively slow to respond, and their clamping voltage varies with current changes, making it difficult to control precisely. In contrast, the SMAJ6.5A can respond in nanoseconds, and its clamping voltage remains stable, offering better protection for current sensors. Compared with gas discharge tubes, the SMAJ6.5A is smaller in size and more suitable for integration into compact current sensor circuits.

Conclusion

The SMAJ6.5A transient voltage suppression diode plays a critical role in protecting current sensors with its excellent performance parameters and reliable protection principles. By selecting the SMAJ6.5A appropriately, transient overvoltages can be effectively suppressed, safeguarding the core components of current sensors and improving system reliability and stability. In practical applications, engineers should consider factors such as the sensor’s operating voltage, current, and environment when selecting the appropriate model and parameters of the SMAJ6.5A, and follow circuit design standards during installation and debugging to maximize its protective effectiveness. With the continued development of electronic technology, transient voltage suppression diodes like the SMAJ6.5A will see broader applications in current sensors and other fields.

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.