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SEPTEMBER 2002
XR16L2751
2.25V TO 5.5V DUART WITH 64-BYTE FIFO AND POWERSAVE
REV. 1.0.0
GENERAL DESCRIPTION
The XR16L2751
1
(2751) is a low voltage dual
universal asynchronous receiver and transmitter
(UART) with 5 Volt tolerant inputs. The device
includes 2 additional capabilities over the
XR16L2750: Intel and Motorola data bus selection
and a “PowerSave” mode to further reduce sleep
current to a minimum during sleep mode. The 2751’s
register set is compatible to the ST16C2550 and
XR16C2850 but with added functions. It supports the
Exar’s enhanced features of 64 bytes of TX and RX
FIFOs, programmable FIFO trigger level, FIFO level
counters, automatic hardware and software flow
control, automatic RS-485 half duplex direction
control with programmable turn-around delay, 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 UART
channel to support data rates up to 6.25 Mbps.
N
OTE
:
1 Covered by U.S. Patent #5,649,122 and #5,832,205
FEATURES
•
2.25 to 5.5 Volt Operation
•
5 Volt Tolerant Inputs
•
Functionally Compatible to ST16C2550 and
XR16C2850 with 4 additional inputs
•
Intel or Motorola Data Bus Interface Select
•
Two Independent UARTs
s
s
s
s
s
s
s
s
s
s
APPLICATIONS
Up to 6.25 Mbps at 5 Volt, 4 Mbps at 3.3 Volt,
and 3 Mbps at 2.5 Volt with 8X sampling rate
64 bytes of Transmit and Receive FIFOs
Transmit and Receive FIFO Level Counters
Programmable TX and RX FIFO Trigger Levels
Automatic Hardware (RTS/CTS) Flow Control
Selectable RTS Flow Control Hysteresis.
Automatic Software (Xoff/Xon) Flow Control
Automatic RS-485 2-wire Half-duplex Direction
Control to the Transceiver via RTS#
Full Modem Interface
Infrared Receive and Transmit Encoder/
decoder
•
Portable and Battery Operated Appliances
•
Wireless Access Servers
•
Ethernet Network Routers
•
Cellular Data Devices
•
Telecommunication Network Routers
•
Factory Automation and Process Controls
F
IGURE
1. XR16L2751 B
LOCK
D
IAGRAM
•
PowerSave Feature reduces sleep current to 15 µA
at 3.3 Volt
•
Device Identification
•
Crystal or external clock input
•
Industrial and Commercial Temperature ranges
•
48 TQFP Package (7 x 7 x 1.0 mm)
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#
CLKSEL
HDCNTL#
Intel or
Motorola
Data Bus
Interface
*5 Volt Tolerant Inputs
2.25 to 5.5 Volt VCC
GND
UART Channel A
UART
Regs
BRG
64 Byte TX FIFO
TX & RX
IR
ENDEC
TXA, RXA, DTRA#,
DSRA#, RTSA#,
DTSA#, CDA#, RIA#,
OP2A#
64 Byte RX FIFO
TXB, RXB, DTRB#,
DSRB#, RTSB#,
CTSB#, CDB#, RIB#,
OP2B#
XTAL1
XTAL2
UART Channel B
(same as Channel A)
Crystal Osc/Buffer
2751BLK
Exar
Corporation 48720 Kato Road, Fremont CA, 94538
•
(510) 668-7000
•
FAX (510) 668-7017
•
www.exar.com
EXAR [ EXAR CORPORATION ]
