SMCJ75

TVS - Diodes: SMCJ75 application field and working principle

Surge protection components are critical components used in safety-critical applications. Among them, TVS (transient voltage suppressor) diodes are commonly used in many consumer electronic and industrial electronic applications. SMCJ75, an unidirectional TVS diode, is specifically designed for transient over-voltage protection. It is widely used in protection applications for computers, industrial control systems and telecommunications.

Feature of SMCJ75

The SMCJ75 offers reliable protection from transients up to 400W peak pulse power for up to 8.3/20 μs pulse width and 150mJ for 1.2-100μs pulse width. It comes with a wide operating voltage range from 5V to 170V with a breakover voltage of 155V. The device offers low leakage current of 0.05mA at rated voltage, and it features superior clamping behavior compared to other transient voltage suppressor diodes. SMCJ75 also features an element-sealed construction, making it ideal for high humidity environments.

Application Fields of SMCJ75

Considering its features, SMCJ75 provides reliable overvoltage protection for a wide range of applications, including:

• Lighting and LEDs systems
• Industrial control systems
• Computer and peripherals
• Telecommunication equipments
• Military and aerospace equipments
• Automotive control systems

Working Principle of SMCJ75

When surge voltage occurs, the voltage across the PN junction of SMCJ75 increases until the zener voltage threshold is reached, and then voltage is quickly clamped to a fixed voltage by the device. The clamping voltage of SMCJ75 varies slightly over its rated operating voltage, depending on the clamping ratio of the part. Regardless of the part’s operating voltage, this clamping voltage is more than enough to protect the device.

When a surge occurs and the applied voltage exceeds the rated voltage, SMCJ75 rapidly starts clamping to the operating voltage. Then, the voltage across the component drops to the threshold voltage and the current decreases rapidly. This current could cause a voltage drop across the load and the protecting device. This voltage drop across the load and the SMCJ75 will depend on their respective impedances and is determined by the duty cycle of the surge waveform.

In summary, SMCJ75 provides superior performance for transient overvoltage protection, and it’s widely used in many safety-critical applications. With its element-sealed construction and wide voltage range, the device serves as an efficient and reliable protection element.