2025

Can an RJ45 Ethernet Jack work without a transformer?

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RJ45 Ethernet Jack (referring to the physical interface circuit on the device, such as the interface of a network card or switch) In most cases, a transformer cannot be omitted. This is determined by Ethernet standards and practical application needs. The specific reasons are as follows:

1. Ethernet standards mandate

The IEEE 802.3 Ethernet standard clearly stipulates that the network interface circuit must include a network transformer ( pulse transformer ) as a necessary component of the physical layer. This is to ensure device compatibility, signal integrity, and security; any standard-compliant device must adhere to this requirement.

2. The core function of the transformer is irreplaceable.

The network transformer is the "safety barrier" and "signal stabilizer" of the interface circuit, with core functions including:

Electrical isolation : Isolates the internal circuit of the device from the ground potential difference of the external network cable (such as the common-mode voltage generated when the grounding voltages of different devices are different), preventing electrostatic discharge, lightning strikes, and power grid fluctuations from directly damaging the PHY chip (physical layer chip).
Anti-interference and signal purification : Suppresses common-mode noise during transmission (such as electromagnetic interference EMI), ensuring stable transmission of differential signals, especially crucial over long distances (more than 1 meter) or in complex electromagnetic environments.
Impedance matching : Matches the impedance of the network cable (typical impedance 100Ω) with the output impedance of the PHY chip, reducing signal reflection, avoiding signal attenuation or distortion, and ensuring normal transmission at rates such as 10/100/1000Mbps.

3. Serious risks of omitting the transformer

If the interface circuit does not include a transformer, even temporary connections over short distances (such as a few tens of centimeters) may seem to work, but there are fatal problems:

Equipment is easily damaged : External electrostatic discharge, lightning strikes, or ground potential differences can directly destroy core components such as the PHY chip, with almost no protection.
Signal is extremely unstable : Lack of anti-interference and impedance matching; electromagnetic interference (such as nearby motors, high-frequency equipment) can cause packet loss, rate drops, or even complete disconnection.
Compatibility failure : Non-standard interfaces cannot communicate normally with other compliant devices, nor can they pass CE, FCC, and other certifications, preventing them from entering the market.

4. Are there any exceptions?

Only in extremely special scenarios (such as short-distance testing in a laboratory, customized ultra-short connections, and completely interference-free, without considering safety) may temporarily omit the transformer, but this is a non-standard operation and has no practical application value (for example, direct connection testing within 20 centimeters, requiring strict interference shielding).

Summary

RJ45 Ethernet Jack must include a transformer , this is a mandatory requirement of the Ethernet standard and is also the core design for ensuring equipment safety, signal stability, and compatibility. Omitting the transformer will result in fragile equipment, unreliable communication, and non-compliance with industry standards, therefore it is absolutely infeasible in practical applications.

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Can SFP optical modules with wavelengths of 850nm and 1310nm be used interchangeably?

What transmission medium does the RJ45 connector connect to?

Can SFP optical modules with wavelengths of 850nm and 1310nm be used interchangeably?

What transmission medium does the RJ45 connector connect to?

Can 850nm and 1310nm optical modules be used together?

2025-07

Can SFP optical modules with wavelengths of 850nm and 1310nm be used interchangeably?

Whether 850nm and 1310nm SFP optical modules can be shared depends on the specific scenario. The core principle is that wavelengths must match for communication, but indirect sharing may be possible with specific technical support. A detailed analysis is as follows