The CCD (Charge-Coupled Device) is a core component that converts optical signals into electrical signals by utilizing the photoelectric effect and charge transfer mechanism. Its working process is as follows: the photodiode array captures photons → the photoelectric effect generates electron-hole pairs → the MOS capacitor potential well stores charges → the clock pulse drives the charges to transfer unit by unit → the output amplifier converts them into voltage signals → the analog-to-digital converter generates digital images.

Comparing the core advantages and application fields of CMOS

Although most civilian applications have now been replaced by CMOS, it still holds an irreplaceable position in specialized fields that have strict requirements for image quality, sensitivity, and noise. 

· Scientific research: astronomical telescopes for imaging, particle physics detectors, and spectral analysis equipment; 

· Medical field: X-ray imaging equipment, fluorescence microscopes, mammography machines; 

· Industrial inspection: High-precision machine vision (such as semiconductor wafer defect detection, automotive component size measurement); 

Aerospace and military industry: Satellite remote sensing cameras, infrared night vision equipment, missile guidance systems.

CCD sensor circuit structure

CCD Sensor Electrostatic Protection Scheme

In scenarios such as high-precision industrial vision and aerospace equipment, electrostatic surges mainly invade through the following paths: power ports: Industrial power sources (such as 24V) are susceptible to surge waves induced by lightning strikes; data interfaces: High-speed image transmission interfaces (such as Camera Link, LVDS); trigger signal lines: External control signal input ports. 

Input power protection 

The 24V industrial power supply needs to provide both surge and overcurrent protection: 

Surge protection: Recommended TVS device LM1K24CA (SMB package, VC = 35V, low clamping voltage), with protection level up to 2KV; Overcurrent protection: SMD1812 series PTC (6-60V, 0.1-3.5A), fast response, reusable; Reverse polarity protection: Schottky diode SK56C (60V/5A), reduces the risk of damage when the power supply is reversed. 

2. Protection of High-Speed Data Interfaces 

Camera Link interface (with a maximum transmission rate of 2.38 Gbps): 

ESD protection: Utilize ULC3304P10LV ESD array (with parasitic capacitance < 0.5pF), meeting IEC61000-4-2 Class 4 (contact discharge 8kV, air discharge 15kV), ensuring high-frequency signal integrity; Common-mode interference suppression: Series common-mode choke coil to reduce crosstalk in data lines. 

The LVDS interface offers a transmission speed of 655 Mbit/s. This solution adopts integrated device protection, with parasitic capacitance less than 1 pf, ensuring signal integrity and meeting IEC 61000-4-2, level 4, with contact discharge of 8 kV and air discharge of 15 kV.

4. Power rail static protection

CCD sensors usually require multiple power rails: 

Simulation power supply (3.3V): ESD0321CW (DFN0603 package, 30pF capacitor, 21A discharge current); 

Digital power supply (1.8V/1.2V): ESD1821C (DFN0603, 25pF, 18A), reduces power supply ripple and electrostatic interference.

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.