XR16L2551 LOW VOLTAGE DUART WITH POWERSAVE MAY 2007 REV. 1.1.3 FEATURES GENERAL DESCRIPTION 2.25 to 5.5 Volt Operation The XR16L2551 (L2551) is a low voltage dual universal asynchronous receiver and transmitter 5 Volt Tolerant Inputs (UART) with 5 Volt tolerant inputs. The device Intel or Motorola Bus Interface Select (16/68 ) includes additional capability over the ST16C2550: pin Intel and Motorola data bus interface selection, hardware and software flow control, infrared encoder/ Pin-to-pin compatible to XR16L2751CM decoder, sleep mode and a PowerSave mode for Two Independent UARTs battery operation. The L2551s enhanced register set is compatible to the ST16C2550 and XR16L2550. It Up to 3.125 Mbps at 5V, 2 Mbps at 3.3V, and 1 supports the Exars enhanced features of 16 bytes of Mbps at 2.5V with external clock input TX and RX FIFOs and a complete modem interface. Up to 1.5 Mbps at 5V, 1.25 Mbps at 3.3V and 1 Onboard registers provide the user with operational Mbps at 2.5V with crystal clock input status and data error tags. An internal loopback 16 bytes of Transmit and Receive FIFOs capability allows onboard diagnostics. Independent Automatic RTS/CTS hardware flow control programmable baud rate generator is provided in each channel to support data rates up to 3.125 Mbps. Automatic Xon/Xoff software flow control Wireless infrared encoder/decoder NOTE: 1 Covered by U.S. Patent 5,649,122. Receive FIFO trigger levels select APPLICATIONS Programmable character lengths (5, 6, 7 or 8) Battery Operated Instruments with even, odd, forced or no parity Data Port Adapters Full Modem Interface (CTS , RTS , DSR , DTR , RI , CD ) in the 48-TQFP package Handheld Appliances Sleep Mode with PowerSave feature for battery Radio Frequency Data Modems operation Base Stations Industrial Temperature range USB Hubs Tiny 32-QFN, no lead package (5x5x0.9mm) Industrial Automation Controls 48-TQFP Package FIGURE 1. XR16L2551 BLOCK DIAGRAM 2.25 to 5.5 Volt VCC *5 Volt Tolerant Inputs PwrSave GND A2:A0 D7:D0 UART Channel A IOR (VCC) TXA, RXA, IOW (R/W ) 16 Byte TX FIFO UART RTSA , CTSA , CSA (CS ) Regs IR ( DTR , DSR TX & RX CSB (A3) ENDEC CD , RIA , OP2A ) BRG INTA (IRQ ) 16 Byte RX FIFO INTB (logic 0) Intel or TXB, RXB, Motorola UART Channel B RTSB , CTSB , Data Bus TXRDYA (same as Channel A) ( DTRB , DSRB TXRDYB Interface CDB , RIB , OP2B ) RXRDYA RXRDYB XTAL1 Crystal Osc/Buffer XTAL2 Reset (Reset ) 16/68 2551BLK Exar Corporation 48720 Kato Road, Fremont CA, 94538 (510) 668-7000 FAX (510) 668-7017 www.exar.com XR16L2551 LOW VOLTAGE DUART WITH POWERSAVE REV. 1.1.3 FIGURE 2. PIN OUT ASSIGNMENT D6 1 24 RESET 1 24 RESET (Reset) D6 D7 2 23 RTSA 2 23 RTSA D7 RXB 3 22 INTA IRQ XR16L2551 RXB 3 22 RXA 4 21 INTB XR16L2551 32-pin QFN in 4 21 NC (INTB) RXA TXA A0 5 20 32-pin QFN in 16 (Intel) Mode TXA 5 20 A0 TXB 19 A1 6 68 (Motorola) Mode TXB 6 19 A1 7 18 A2 VCC CSA A2 CS 7 18 8 17 CSB 16/68 A3 (CSB ) 8 17 16/68 GND D5 1 36 RESET D5 1 36 RESET 2 35 DTRB 2 35 DTRB D6 D6 D7 3 34 DTRA D7 3 34 DTRA RTSA RTSA RXB 4 33 RXB 4 33 RXA 5 32 OP2A RXA 5 32 OP2A XR16L2551 XR16L2551 6 31 RXRDYA 6 31 RXRDYA TXRDYB TXRDYB 48-pin TQFP 48-pin TQFP in TXA 7 30 INTA TXA 7 30 IRQ in 16 (Intel) Mode 68 (Motorola) Mode) INTB NC TXB 8 29 TXB 8 29 OP2B 9 28 A0 OP2B 9 28 A0 A1 A1 CSA 10 27 CS 10 27 CSB 11 26 A2 A3 11 26 A2 NC NC PWRSAVE 12 25 PWRSAVE 12 25 VCC GND ORDERING INFORMATION OPERATING TEMPERATURE PART NUMBER PACKAGE DEVICE STATUS RANGE XR16L2551IL 32-Lead QFN -40C to +85C Active XR16L2551IM 48-Lead TQFP -40C to +85C Active 2 XTAL1 13 48 D4 XTAL2 14 47 D3 IOW 15 46 D2 PWRSAVE 32 D5 9 CDB 16 45 D1 XTAL1 10 31 D4 XTAL2 11 30 D3 GND 17 44 D0 IOW 12 29 D2 RXRDYB 18 43 TXRDYA 28 GND 13 D1 IOR 19 42 VCC 14 27 D0 IOR DSRB 20 41 RIA RTSB 15 26 VCC RIB 21 40 CDA CTSB 16 25 CTSA RTSB 22 39 DSRA CTSB 23 38 CTSA 16/68 24 37 NC XTAL1 13 48 D4 XTAL2 47 14 D3 PWRSAVE 9 32 D5 IOW 15 46 D2 XTAL1 31 D4 10 CDB 45 16 D1 XTAL2 11 30 D3 GND 17 44 D0 12 D2 R/W 29 RXRDYB 18 43 TXRDYA GND 13 28 D1 VCC 14 27 D0 19 42 VCC VCC (IOR ) RTSB 15 26 VCC DSRB 20 41 RIA 16 25 CTSB CTSA RIB 21 40 CDA RTSB 22 39 DSRA CTSB 23 38 CTSA 16/68 24 37 NC