help needed for designing poE

You should use an ethernet transformer that is rated for POE and is also compatible with your ethernet PHY (consult your ethernet PHY datasheet or supplier for a recommendation which is POE compatible). H2019NL is used on TPS2375EVM (see schematic below for hookup).

http://www.ti.com/lit/ug/slvu108/slvu108.pdf

ok. i'll do. and is there any thing needed in circuit line of ethernet cable -> jack -> dc convertor for power and transformer for data generation -> dc convertor to TPS237( as shown in reference design of http://www.ti.com/lit/ug/slvu108/slvu108.pdf) and data directly to controller. and what should i do with PG pin of TPS2375. can i left the PG and use VDD ,Vss alone for power.

I would recommend you contact your local TI sales office and they can help direct you to a more specific solution based on the product you are going to create. Then as you proceed with product design, the forum can be used when answers to more specific questions are needed.

This picture shows the general idea. Rx and Tx will go to the PHY. The PHY will need a lower voltage so use a dc/dc converter connected below (and with use of PG to enable the dc/dc converter). If you want a more integrated PoE PD + DC/DC converter then use TPS23753A (see associated EVMs).

actually.. i wanna use tps2375-1 ic for my project , that has suited well.  and in order to take further steps can you please support me in designing  circuit with an output of 14v and 1A. i had gone through switcher pro software. it has suggested some example circuit with TPS54160. and in that my doubt is how to make this as suited for power good.