The XR20M11701 (M1170) is a high performance universal asynchronous receiver and transmitter (UART) with 64 byte TX and RX FIFOs and a selectable I2C/SPI slave interface. The M1170 operates from 1.62 to 3.63 volts. The enhanced features in the M1170 include a programmable fractional baud rate generator, an 8X and 4X sampling rate that allows for a maximum baud rate of 16 Mbps at 3.3V. The standard features include 16 selectable TX and RX FIFO trigger levels, automatic hardware (RTS/CTS) and software (Xon/Xoff) flow control, and a complete modem interface. Onboard registers provide the user with operational status and data error flags. An internal loopback capability allows system diagnostics. The M1170 is available in the 28-pin QFN, 24-pin QFN, 16-pin QFN, 24-pin TSSOP and 16-pin TSSOP packages. The 28-pin QFN package has the EN485# and ENIR# pins to allow the UART to power-up in the Auto RS485 mode or the Infrared mode.