The XR16V27521 (V2752) is a high performance dual universal asynchronous receiver and transmitter (UART) with 64 byte TX and RX FIFOs. The device operates from 2.25 to 3.6 volts with 5 Volt tolerant inputs and is pin-to-pin compatible to Exar's ST16C2552, XR16L2552 and XR16L2752. The V2752 register set is identical to the XR16L2752 and is compatible to the ST16C2552 and the XR16C2852 enhanced features. It supports the Exar's enhanced features of programmable FIFO trigger level and FIFO level counters, automatic hardware (RTS/CTS) and software flow control, automatic RS-485 half duplex direction control output and a complete modem interface. Onboard registers provide the user with operational status and data error flags. An internal