CMOS Sensor: A Precise Dance of Light and Electricity 

CMOS sensors are photoelectric conversion devices that use semiconductor processes to convert photons into electrical charges. The photoelectric conversion process: the photodiode array captures photons → generates electron charges → MOS transistors convert them into voltage signals → ADC outputs digital images.

With its three advantages of low power consumption, high integration and low cost, CMOS sensors have gradually replaced CCD sensors and are widely used in fields such as smartphone cameras, security monitoring, medical imaging, automotive electronics, industrial inspection, aerospace and military industries.

Leiditech EMCColleague drew the following block diagram using the common architecture of industrial machine vision cameras.：

As for the conventional application of CMOS sensors, the main paths for electrostatic surge intrusion in industrial vision cameras are the power supply, high-speed data interfaces, and trigger signal lines. 

The protective solution recommended by Lebao Electronics for the aforementioned key interfaces: 

Input power protection: 

The 24V industrial power supply is susceptible to surge waves induced by lightning strikes. The recommended TVS LM1K24CA has a small package, SMB type, low residual voltage, VC = 35V. It can reduce the cost of the withstand voltage of LDO or DC-DC, and the protection level reaches 2KV. Overcurrent protection is recommended by the SMD1812 series PTC. Anti-reverse polarity protection is recommended to use SK56C (60V, 5A).

l CMOS high-speed data interface MIPI CSI-2

MIPI offers a transmission speed of 2.5 Gbit/s. Lebao adopts the ESD array integrated device ULC3304P10LV for protection, with parasitic capacitance less than 0.5 pf, ensuring signal integrity and meeting IEC 61000-4-2, level 4, contact discharge of 8 kV, and air discharge of 15 kV.

Electrostatic protection for the power supply of CMOS sensors

CMOS image sensors usually require three power rails with specific sequences, used for the analog part, the pixel part (or interface part), and the digital part. The voltage of the analog power rail is typically 3.3V, the voltage of the pixel power rail (or interface power rail) is usually 3.3V or 1.8V, and the voltage of the digital power rail is typically 1.8V or 1.2V.

For 2V and 1.8V power supplies, the recommended ESD1821C should be used. For 3.3V power supplies, the recommended ESD0321CW should be adopted (refer to the table at the end for parameters).

Leiditech is committed to becoming a leading brand in electromagnetic compatibility solutions and component supply, offering products such as ESD, TVS, TSS, GDT, MOV, MOSFET, Zener, and inductors. Leiditech has an experienced R&D team that can provide personalized customization services based on customer needs, offering the best solutions to customers.