FAQs – Magnetics

These speed designations reflect the maximum data throughput the port can handle. For instance:

• 10/100 Base-T: Up to 100 Mbps, common in basic networking.
• 1G Base-T: Up to 1 Gbps, standard in most modern LANs.
• 2.5G Base-T, 5G Base-T, 10G Base-T: Higher speeds for bandwidth-intensive applications like video streaming or large data transfers.
• Cat5E: A cable category supporting up to 1 Gbps (and sometimes 2.5G/5G in short runs).

These configurations describe how many RJ45 ports are grouped together in a single connector module. A 1×1 has one port in one row, while 2×4 has eight ports arranged in two rows of four. Higher port density saves PCB space and is useful for multi-port switches or network equipment.

“Tab Direction” refers to where the latch on the RJ45 plug is oriented. For instance, “Down” means the latch faces downward. This impacts how easily cables can be inserted or removed and helps with space management on crowded PCBs.

These ratings indicate how much current the RJ45 jack can handle for Power over Ethernet. A higher PoE rating supports more power-intensive devices (e.g., IP cameras, access points), while Non-PoE jacks don’t carry power at all. Designers must ensure compatible transformers and PCB traces to handle the required current safely.

• Mounting Angle: Right-angle jacks are commonly used on edges of boards for easy cable access; vertical jacks save lateral space and are often used when vertical cable entry is needed.
• Mounting Style:
  • SMD/SMT (Surface Mount): Allows automated placement and soldering, reducing assembly costs.
  • THT (Through-Hole): Provides stronger mechanical support, often preferred in rugged environments.

LAN transformers are matched to the data rate they support. Higher-speed transformers (10G Base-T, 5G Base-T) must handle faster signal transitions and tighter tolerances, ensuring signal integrity at elevated frequencies. Dual 1G Base-T designs can handle two Gigabit lines in one module, saving space and simplifying multi-port applications.

Inductance measures the transformer’s ability to filter out high-frequency noise and maintain signal quality. Higher inductance can provide better common-mode noise suppression, but design must balance inductance with insertion loss, bandwidth, and physical size.

The “Number of Ports” indicates how many independent Ethernet channels a single module supports. For example, a 4-port LAN transformer can handle four separate Ethernet links, ideal for multi-port switches or high-density networking equipment.

These ratings specify how much current each port can carry for Power over Ethernet. Non-PoE transformers handle data only, while higher PoE ratings (up to 1.1A) support devices with larger power draws, such as VoIP phones, PTZ cameras, or wireless access points.

BMS (Battery Management System) transformers provide galvanic isolation and signal coupling for battery monitoring and balancing circuits. The “Number of channels” indicates how many separate isolated signals can pass through one transformer module, crucial for multi-cell battery packs.

“Working Voltage” defines the maximum continuous DC voltage the transformer can safely isolate. Higher voltage ratings are essential in large battery packs (e.g., electric vehicles) to ensure safe operation and compliance with electrical standards.

• Isolation Focus: BMS transformers prioritize robust isolation for battery modules rather than high-frequency data transmission (as in LAN).
• Voltage Levels: They handle higher DC voltages typical in battery packs.
• Thermal Considerations: BMS transformers often face elevated temperatures inside battery enclosures and must meet stricter safety certifications.

Common mode chokes suppress electromagnetic interference (EMI) and noise on balanced data lines. In automotive or industrial Ethernet (like 100 Base-T1), they help maintain signal integrity by filtering out unwanted currents that travel in the same direction on both wires.

Inductance impedes high-frequency noise currents, allowing differential data signals to pass while attenuating common-mode noise. The choke’s inductive reactance effectively blocks unwanted signals without degrading the primary data signal.

Chokes must handle the operating current and voltage of the data lines without saturating or overheating. Underrated chokes can lead to signal distortion, reduced reliability, or failure under load.

Automotive/industrial chokes are typically designed for higher temperatures, vibration resistance, and stricter EMI standards. They often have specialized mechanical forms and meet automotive-grade or industrial-grade reliability requirements.