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SEPTEMBER 2003
XR16L2550
LOW VOLTAGE DUART WITH 16-BYTE FIFO
REV. 1.0.0
GENERAL DESCRIPTION
The XR16L2550
1
(L2550) is a dual universal
asynchronous receiver and transmitter (UART). The
XR16L2550 is an improved version of the
ST16C2550 UART with lower operating voltages and
5 volt tolerant inputs. The L2550 provides enhanced
UART functions with 16 byte FIFOs, a modem control
interface and data rates up to 4 Mbps. Onboard
status registers provide the user with error indications
and operational status. System interrupts and modem
control features may be tailored by external software
to meet specific user requirements. Independent
programmable baud rate generators are provided to
select transmit and receive clock rates up to 3.125
Mbps. The Baud Rate Generator can be configured
for either crystal or external clock input. An internal
loopback capability allows onboard diagnostics. The
L2550 is available in a 44-pin PLCC, 48-pin TQFP
and 32-pin QFN packages. The L2550 is fabricated in
an advanced CMOS process.
N
OTE
:
1 Covered by U.S. Patent #5,649,122.
FEATURES
•
2.25 to 5.5 Volt operation
•
5 Volt tolerant inputs
•
Pin-to-pin compatible to Exar’s ST16C2450,
ST16C2550 and XR16L2750 in 44-PLCC and 48-
TQFP packages
•
Pin-to-pin compatible to XR16C2850 in 44-PLCC
•
Pin alike XR16L2551, XR16L2751 and XR16C2850
in 48-TQFP package
•
Two independent UART channels
s
s
s
Up to 3.125Mbps with external clock of 50 MHz
Register Set compatible to 16C550
16 byte Transmit FIFO to reduce the bandwidth
requirement of the external CPU
16 byte Receive FIFO with error tags to reduce
the bandwidth requirement of the external CPU
4 selectable Receive FIFO interrupt trigger
levels
Automatic RTS/CTS hardware flow control
Automatic Xon/Xoff software flow control
Wireless infrared encoder/decoder
Full Modem Interface (CTS#, RTS#, DSR#,
DTR#, RI#, CD#)
Programmable character lengths (5, 6, 7, 8)
with even, odd, or no parity
s
s
APPLICATIONS
s
s
s
s
•
Portable Appliances
•
Medical Monitors
•
Base Stations
•
Micro Servers
•
Telecommunication Network Routers
•
Industrial Automation Controls
F
IGURE
1. XR16L2550 B
LOCK
D
IAGRAM
s
•
Tiny 32-QFN, no lead package (5x5x0.9mm)
•
44-PLCC and 48-TQFP packages also available
A2:A0
D7:D0
IOR#
IOW#
CSA#
CSB#
INTA
INTB
TXRDYA#
TXRDYB#
RXRDYA#
RDRXYB#
Reset
8-bit Data
Bus
Interface
* 5 Volt Tolerant Inputs
2.25 to 5.5 Volt VCC
GND
UART Channel A
UART
Regs
BRG
16 Byte TX FIFO
TX & RX
16 Byte RX FIFO
TXB, RXB, DTRB#,
DSRB#, RTSB#,
CTSB#, CDB#, RIB#,
OP2B#
XTAL1
XTAL2
TXA, RXA, DTRA#,
DSRA#, RTSA#,
DTSA#, CDA#, RIA#,
OP2A#
UART Channel B
(same as Channel A)
Crystal Osc/Buffer
Exar
Corporation 48720 Kato Road, Fremont CA, 94538
•
(510) 668-7000
•
FAX (510) 668-7017
•
www.exar.com
EXAR [ EXAR CORPORATION ]
