ST16C550 UART WITH 16-BYTE FIFOs April 2005 GENERAL DESCRIPTION PLCC Package The ST16C550 (550) is a universal asynchronous re- ceiver and transmitter with 16 byte transmit and receive FIFO. It operates at 2.97 to 5.5 volts. A programmable baud rate generator can select transmit and receive clock rates from 50 bps to 1.5 Mbps. D5 7 39 RESET The ST16C550 is an improved version of the NS16C550 D6 8 38 -OP1 UART with higher operating speed and lower access 9 37 -DTR D7 time. The ST16C550 on board status registers provides RCLK 10 36 -RTS the error conditions, type and status of the transfer 11 35 RX -OP2 operation being performed. Included is complete MO- N.C. 12 34 N.C. ST16C550CJ44 DEM control capability, and a processor interrupt 13 33 TX INT system that may be software tailored to the users CS0 14 32 -RXRDY requirements. The ST16C550 provides internal loop- 31 CS1 15 A0 back capability for on board diagnostic testing. -CS2 16 30 A1 The ST16C550 is available in 40 pin PDIP, 44 pin PLCC, 17 29 -BAUDOUT A2 and 48 pin TQFP packages. It is fabricated in an advanced CMOS process to achieve low drain power and high speed requirements. FEATURES Pin to pin and functionally compatible to the Industry Standard modem interface Standard 16C550 Compatible with ST16C450 2.97 to 5.5 volt operation Low operating current ( 1.2mA typ.) 24MHz clock operation at 5V 16MHz clock operation at 3.3V 16 byte transmit FIFO 16 byte receive FIFO with error flags Full duplex operation Transmit and receive control Four selectable receive FIFO interrupt trigger levels ORDERING INFORMATION Part number Package Operating temperature Device Status ST16C550CP40 40-Lead PDIP 0 C to + 70 C Active. See the ST16C550CQ48 for new designs. ST16C550CJ44 44-Lead PLCC 0 C to + 70 C Active ST16C550CQ48 48-Lead TQFP 0 C to + 70 C Active ST16C550IP40 40-Lead PDIP -40 C to + 85 C Active. See the ST16C550IQ48 for new designs. ST16C550IJ44 44-Lead PLCC -40 C to + 85 C Active ST16C550IQ48 48-Lead TQFP -40 C to + 85 C Active Rev. 5.01 EXAR Corporation, 48720 Kato Road, Fremont, CA 94538 (510) 668-7000 FAX (510) 668-7017 18 6 XTAL1 D4 XTAL2 19 5 D3 20 -IOW 4 D2 IOW 21 3 D1 22 GND 2 D0 N.C. 23 1 N.C. 24 -IOR 44 VCC IOR 25 43 -RI 26 -DDIS 42 -CD -TXRDY 27 41 -DSR 28 -AS 40 -CTSST16C550 Figure 1, PACKAGE DESCRIPTION, ST16C550 48 Pin TQFP Package 40 Pin DIP Package D0 1 40 VCC D1 2 39 -RI D2 3 38 -CD N.C. 1 36 N.C. D3 4 37 -DSR D5 2 35 RESET -CTS D4 5 36 D6 3 34 -OP1 RESET D5 6 35 D7 4 33 -DTR D6 7 34 -OP1 -RTS RCLK 5 32 D7 8 33 -DTR N.C. 6 31 -OP2 ST16C550CQ48 7 30 INT RCLK 9 32 -RTS RX TX 8 29 -RXRDY RX 10 31 -OP2 CS0 9 28 A0 TX 11 30 INT CS1 10 27 A1 CS0 12 29 -RXRDY -CS2 11 26 A2 A0 CS1 13 28 N.C. -BAUDOUT 12 25 A1 -CS2 14 27 15 26 A2 -BAUDOUT XTAL1 16 25 -AS XTAL2 17 24 -TXRDY -IOW 18 23 -DDIS IOW 19 22 IOR GND 20 21 -IOR Rev. 5.01 2 N.C. 13 48 N.C. 47 XTAL1 14 D4 XTAL2 15 46 D3 45 -IOW 16 D2 IOW 17 44 D1 GND 43 D0 18 -IOR 19 42 VCC IOR 20 41 -RI 40 N.C. 21 -CD -DDIS 22 39 -DSR -TXRDY 38 -CTS 23 -AS 24 37 N.C. ST16C550CP40