The TDA5051AT/C1.512 is an ISDN/VDSL2 transceiver chip manufactured by NXP (formerly Philips). It is used in applications such as ISDN, VoIP, and VDSL2. The chip supports speeds up to 50 Mbps, and features integrated line coding, echo cancellation, and automatic gain control. It also has built-in power fail detect, thermal shutdown and self-protection functions.