SC16C554/554D Quad UART with 16-byte FIFO and infr.
SC16C554DB - 5 V 3.3 V and 2.5 V quad UART
SC16C554 - Quad UART with 16-byte FIFO and infrared (IrDA) encoder/decoder
SC16C554B - 5 V 3.3 V and 2.5 V quad UART
SC16C554D - Quad UART