June 2013


World’s smallest SMD Pulse Transformer for LAN Applications

  • Size of 3.2 x 3.2 x 2.8 mm3 with 30 percent less volume and smaller footprint than existing products
  • More stable product quality thanks to automated winding process

TDK Corporation announces the world’s smallest SMD pulse transformers for LAN applications. With dimensions of only 3.2 x 3.2 x 2.8 mm3, the new ALT3232M has 30 percent lower volume and footprint than previous products. The inductance of the new transformer is 150 μH, its insertion loss is in the frequency range from 100 kHz to 100 MHz at 2.5 dB, and its parasitic winding capacitance is only 25 pF at 100 kHz. Series production will start in July 2013.

The number of pulse transformers used in LAN applications is increasing in response to the raised transmission speed of Ethernet networks, namely from 100 to 1000 Mbps. In addition, several transformers are usually placed on a circuit board, so that minimized component dimensions are of crucial importance.

LAN interfaces are not only used in computers and other IT equipment, but increasingly also in LCD TV sets and other audiovisual appliances. They transmit the pulse-shaped signals at high transmission speeds and at the same time provide electrical insulation between input and output.

By applying technology that has proved its worth in the production of SMD common mode filters, TDK was able to devise an automated winding process suitable for mass production. This reduces characteristics variations that tend to occur with manual winding, and thereby offers enhanced reliability and quality.

Main applications

  • LAN interfaces in notebooks, digital home appliances, etc.
  • Various types of communication equipment

Main features and benefits

  • Reduced size and smaller footprint contribute to space saving
  • Increased reliability and more stable product quality thanks to automated winding process

Key data


Winding ratio

Insertion loss
Parasitic capacitance



* DC bias 8 mA, tolerance ±20%
** 0.1 MHz -100 MHz,
*** 100 kHz,

Terminal layout diagram



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