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SEPTEMBER 2003
XR16L2551
LOW VOLTAGE DUART WITH POWERSAVE
REV. 1.0.0
GENERAGENERAL DESCRIPTION
The XR16L2551 (L2551) is a low voltage dual
universal asynchronous receiver and transmitter
(UART) with 5 Volt tolerant inputs. The device
includes additional capability over the ST16C2550:
Intel and Motorola data bus interface selection,
hardware and software flow control, infrared encoder/
decoder, sleep mode and a PowerSave mode for
battery operation. The L2551’s enhanced register set
is compatible to the ST16C2550 and XR16L2550. It
supports the Exar’s enhanced features of 16 bytes of
TX and RX FIFOs and a complete modem interface.
Onboard registers provide the user with operational
status and data error tags. An internal loopback
capability allows onboard diagnostics. Independent
programmable baud rate generator is provided in
each channel to support data rates up to 3.125 Mbps.
N
OTE
:
1 Covered by U.S. Patent #5,649,122.
FEATURES
•
2.25 to 5.5 Volt Operation
•
5 Volt Tolerant Inputs
•
Intel or Motorola Bus Interface Select (16/68#)
pin
•
Pin-to-pin compatible to XR16L2751CM
•
Two Independent UARTs
s
Up to 3.125 Mbps at 5V, 2 Mbps at 3.3V, and 1
Mbps at 2.5V with external clock input
Up to 1.5 Mbps at 5V, 1.25 Mbps at 3.3V and 1
Mbps at 2.5V with crystal clock input
16 bytes of Transmit and Receive FIFOs
Automatic RTS/CTS hardware flow control
Automatic Xon/Xoff software flow control
Wireless infrared encoder/decoder
Receive FIFO trigger levels select
Programmable character lengths (5, 6, 7 or 8)
with even, odd, forced or no parity
Full Modem Interface (CTS#, RTS#, DSR#,
DTR#, RI#, CD#) in the 48-TQFP package
s
s
s
s
s
s
s
APPLICATIONS
•
Battery Operated Instruments
•
Data Port Adapters
•
Handheld Appliances
•
Radio Frequency Data Modems
•
Base Stations
•
USB Hubs
•
Industrial Automation Controls
F
IGURE
1. XR16L2551 B
LOCK
D
IAGRAM
s
•
Sleep Mode with PowerSave feature for battery
operation
•
Industrial Temperature range
•
Tiny 32-QFN, no lead package (5x5x0.9mm)
•
48-TQFP Package
PwrSave
A2:A0
D7:D0
IOR# (VCC)
IOW# (R/W#)
CSA# (CS#)
CSB# (A3)
INTA (IRQ#)
INTB (logic 0)
TXRDYA#
TXRDYB#
RXRDYA#
RXRDYB#
Reset (Reset#)
16/68#
*5 Volt Tolerant Inputs
2.25 to 5.5 Volt VCC
GND
UART Channel A
UART
Regs
BRG
16 Byte TX FIFO
TX & RX
IR
ENDEC
TXA, RXA,
RTSA#, CTSA#,
( DTR#, DSR#
CD#, RIA#, OP2A# )
16 Byte RX FIFO
TXB, RXB,
RTSB#, CTSB#,
( DTRB#, DSRB#
CDB#, RIB#, OP2B# )
XTAL1
XTAL2
Intel or
Motorola
Data Bus
Interface
UART Channel B
(same as Channel A)
Crystal Osc/Buffer
2551BLK
Exar
Corporation 48720 Kato Road, Fremont CA, 94538
•
(510) 668-7000
•
FAX (510) 668-7017
•
www.exar.com
EXAR [ EXAR CORPORATION ]
