
Exar
Corporation 48720 Kato Road, Fremont CA, 94538
(510) 668-7000
FAX (510) 668-7017
www.exar.com
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XR16L2450
2.25V TO 5.5V DUART
OCTOBER 2004
GENERAL DESCRIPTION
REV. 1.1.0
The XR16L2450 (L2450) is a dual universal asyn-
chronous receiver and transmitter (UART). The
XR16L2450 is an improved version of the
ST16C2450 with lower operating voltage and 5 volt
tolerant inputs. The L2450 provides enhanced UART
functions, a modem control interface and data rates
up to 1.5 Mbps. Onboard status registers provide the
user with error indications and operational status. In-
dependent programmable baud rate generators are
provided to select transmit and receive clock rates up
to 1.5 Mbps. An internal loopback capability allows
onboard diagnostics. The L2450 is available in a 44-
pin PLCC and 48-pin TQFP packages. The L2450 is
fabricated in an advanced CMOS process capable of
operating from 2.25 volt to 5.5 volt power supply with
5 volt tolerant inputs.
APPLICATIONS
Portable Appliances
Telecommunication Network Routers
Ethernet Network Routers
Cellular Data Devices
Factory Automation and Process Controls
FEATURES
2.25 to 5.5 Volt Operation
5 Volt Tolerant Inputs
Pin-to-pin compatible to Exar’s ST16C2450,
ST16C2550,
XR16L2550,
XR16C2850
Pin-to-pin compatible to TI’s TL16C752B on the 48-
TQFP package
2 independent UART channels
■
Up to 1.5 Mbps data rate with a 24 MHz crystal
oscillator or external clock frequency
■
1 byte Transmit FIFO
■
1 byte Receive FIFO with error tags
■
Status report registers
■
Modem control signals (CTS#, RTS#, DSR#,
DTR#, RI#, CD#)
■
Programmable character lengths (5, 6, 7, 8)
with even, odd, or no parity
Crystal oscillator or external clock input
TTL compatible inputs, outputs
Industrial temperature ranges
48-TQFP and 44-PLCC packages
XR16L2750
and
F
IGURE
1. XR16L2450 B
LOCK
D
IAGRAM
XTAL1
XTAL2
Crystal Osc/Buffer
TXA
RTSA#, CTSA#,
DTRA#, DSRA#,
CDA#, RIA#, OP2A#
8-bit Data
Bus
Interface
UART Channel A
BRG
THR
UART
Regs
2.25 to 5.5 Volt VCC
UART Channel B
(same as Channel A)
A2:A0
D7:D0
IOR#
CSA#
CSB#
INTA
INTB
IOW#
Reset
RHR
Modem I/Os
RXA
TXB
RXB
RTSB#, CTSB#,
DTRB#, DSRB#,
CDB#, RIB#, OP2B#
*5V Tolerant inputs