Ethernet Protection And ESD Protection Design

As the integration level of integrated circuits becomes higher and higher, the circuits become more and more complex, the operating voltage becomes lower and lower, and the requirements for  environmental stability are also higher.

On the one hand, due to the high integration of the internal structure of electronic equipment, the  level of withstand voltage and overcurrent resistance of the equipment is reduced, and the ability to withstand overvoltage and overcurrent is reduced. On the other hand, due to the increase in signal source paths, the system is more vulnerable Overpressure and overcurrent intrusion.

Due to the increasing competition in the telecommunications and industrial control industry, the demand for high-reliability network equipment provided by telecommunications equipment suppliers and communication product suppliers has also increased relatively. The hazards of overvoltage andarious static electricity are usually caused by: lightning strikes, induction caused by nearby wires, direct contact with power lines, or user equipment failures. These hazards may endanger telecommunications network equipment users and maintenance personnel. Therefore, telecommunication equipment suppliers have increased the equipment's ability to resist overvoltage and overcurrent to reduce system maintenance costs and improve the reliability.

● Conform to IEC61000-4-4 (EFT): 40A-5 / 50ns

● Comply with IEC61000-4-5 (Surge): 24A, 8 / 20µs-Level 2 (Line-Ground) & Level 3 (Line-Line)

● Low junction capacitance: 3pF Typical

● RoHS compliant

● Simple and convenient design

Option 1

10 / 100M Ethernet port Applicable conditions: Use a network cable to connect the device that is less than 10M away from the fully exposed direct lightning zone

Test standard: TU-T K.21 (10/700 μS) Impedance (40Ω) Differential mode: 1.0KV Common mode: 6.0KV

Option 2

10 / 100M Ethernet port Applicable conditions: Fully exposed direct lightning strike interval Test standard: IEC61000-4-5 1.2 / 50 & 8 / 20μS Impedance (2Ω) Differential mode: 6KV Common mode

Option 3

100M / Gigabit Ethernet port Applicable conditions: Fully exposed direct lightning strike interval Test standard: TU-T K.21 (10/700 μS) Impedance (40Ω) Differential mode: 1.0KV Common mode: 6.0KV

Note: The resistance of R1 ~ R4 is called BST (Bob Smith Terminal) .The purpose is to match the impedance between two pairs of twisted pairs, which is conducive to signal transmission and greatly helps electromagnetic radiation.

Device Selection	GDT	ESD
	GDT/SMD1812-091	ESDLC3V0D3B

The scheme chooses the first stage to use a GDT gas discharge tube to discharge the surge current to the ground through a switch-type gas discharge tube, or the inert gas arc of the discharge tube electrode is eliminated in the form of heat.In the middle, the inductance characteristics of the network transformer are fully utilized to play the role of decoupling and isolation.The second stage uses ESD devices, which can absorb the residual frequency component surge, and the clamping voltage is reduced to about 8V under IPP, so that the Ethernet chip is in a safe protection state!

For POE power, the international IEEE 802.3 standard description and two power methods

IEEE 802.3af Power classification of PSE and PD

Use	Lowest Power Output Level On PSE	Maximum power level on flashlight equipment
Default	15.4W	0.44 to 12.95 W
Optional	4.0W	0.44 to 3.84 W
Optional	7.0W	3.84 to 6.49 W
Optional	15.4W	6.49 to 12.95 W

YINT ELECTRONIC

INT.P0640SCL + PPTC Protect POE

SMCJ58A + PPTC Protect POE

The effect of TVS diodes and semiconductor discharge tubes (thyristor)