TDK has announced SMD pulse transformers for LAN applications with dimensions of only 3.2 x 3.2 x 2.8 mm; the ALT3232M has 30% 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 minimised component dimensions are of crucial importance.
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.