With a look at the data sheet [1], it seems to be a transformer used for signal and power isolation: > The CTI provides all the MAU (transceiver) functions exc

With a look at the data sheet [1], it seems to be a transformer used for signal and power isolation: > The CTI provides all the MAU (transceiver) functions except for signal and power isolation. Signal isolation can easily be provided by a set of three pulse transformers that come in a single Dual-in-Line package. These are available from transformer vendors such as Pulse Engineering (PE64103) and Valor (LTll0l). However, for the power isolation a DC to DC converter is required. The data sheet provides several sample implementations using a PE64018, PE64103, PICO 33223, or PICO 33143 for this. [1] http://www.bitsavers.org/components/national/_dataBooks/1988_National_Data_Communications_Local_Area_Networks_UARTs_Handbook.pdf#page=134&zoom=auto,-207,651 http://www.bitsavers.org/components/national/_dataBooks/1988...