Typical PCB protection devices mainly fall into the following categories:
(1) Resistor-capacitance components. By connecting resistor-capacitance elements on each signal line, they can play a role in PCB shielding. A series resistor can suppress instantaneous peak current, while a parallel grounded capacitor can limit instantaneous peak voltage.
(2) Clamping diodes. Two diodes can clamp transient voltage between positive and negative polarities within a certain range. The series resistance can provide power load, thus offering positive and negative PCB protection.
(3) Zener diode. While not specifically designed for PCB applications, Zener diodes’ working characteristics provide some positive and negative PCB protection. However, their drawback is that the N junction is small, making them unable to withstand large peak currents. Moreover, the parasitic capacitance they generate is significant, which may affect the circuit’s normal operation.
(4) Transient voltage suppressor. Also known as TVS tube, this solid-state diode is specifically designed for PCB protection. Its key features include a short response time and small leakage current, making it an ideal protection device.
(5) Gas discharge tube (GDT). Gas discharge tubes use glass or ceramics with airtight properties as the outer shell. They are filled with stable gases like neon or argon to maintain insulation. The advantages of GDTs include high insulation resistance, low parasitic capacitance, self-recovery capabilities. However, their disadvantages include less-than-ideal response speed and lifespan, as well as gradual decay of electrical properties over time.
(1) Resistor-capacitance components. By connecting resistor-capacitance elements on each signal line, they can play a role in PCB shielding. A series resistor can suppress instantaneous peak current, while a parallel grounded capacitor can limit instantaneous peak voltage.
(2) Clamping diodes. Two diodes can clamp transient voltage between positive and negative polarities within a certain range. The series resistance can provide power load, thus offering positive and negative PCB protection.
(3) Zener diode. While not specifically designed for PCB applications, Zener diodes’ working characteristics provide some positive and negative PCB protection. However, their drawback is that the N junction is small, making them unable to withstand large peak currents. Moreover, the parasitic capacitance they generate is significant, which may affect the circuit’s normal operation.
(4) Transient voltage suppressor. Also known as TVS tube, this solid-state diode is specifically designed for PCB protection. Its key features include a short response time and small leakage current, making it an ideal protection device.
(5) Gas discharge tube (GDT). Gas discharge tubes use glass or ceramics with airtight properties as the outer shell. They are filled with stable gases like neon or argon to maintain insulation. The advantages of GDTs include high insulation resistance, low parasitic capacitance, self-recovery capabilities. However, their disadvantages include less-than-ideal response speed and lifespan, as well as gradual decay of electrical properties over time.
