The MAX3109 advanced dual universal asynchronous receiver-transmitter (UART) has 128 words of receive and transmit first-in/first-out (FIFO) and a high-speed SPI™ or I²C controller interface. The 2x and 4x rate modes allow a maximum of 24Mbps data rates. A phase-locked loop (PLL) and the fractional baud-rate generators allow a high degree of flexibility in baud-rate programming and reference clock selection. Independent logic-level translation on the transceiver and controller interfaces allows ease of interfacing to microcontrollers, FPGAs, and transceivers that are powered by differing supply voltages. Automatic hardware and software flow control with selectable FIFO interrupt triggering offloads low-level activity from the host controller. Automatic half-duplex transceiver control with programmable setup and hold times allow the MAX3109 to be used in high-speed applications such as PROFIBUS-DP. The 128-word FIFOs have advanced FIFO control, reducing host processor data flow management. The MAX3109 is available in a 32-pin TQFN (5mm x 5mm) package, and is specified over the -40°C to +85°C extended temperature range.