XR16L2751_05 Datasheet, PDF (1/52 Pages) Exar Corporation – 2.25V TO 5.5V DUART WITH 64-BYTE FIFO AND POWERSAVE

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XR16L2751
2.25V TO 5.5V DUART WITH 64-BYTE FIFO AND POWERSAVE
OCTOBER 2005
GENERAL DESCRIPTION
FEATURES
REV. 1.2.2
The XR16L2751¹ (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.
NOTE: 1 Covered by U.S. Patent #5,649,122 and #5,949,787
APPLICATIONS
• Portable and Battery Operated Appliances
• Wireless Access Servers
• Ethernet Network Routers
• Cellular Data Devices
• Telecommunication Network Routers
• Factory Automation and Process Controls
• 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
■ 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
• 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)
FIGURE 1. XR16L2751 BLOCK DIAGRAM
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
(Except XTAL1)
UART Channel A
UART
Regs
BRG
64 Byte TX FIFO
TX & RX ^IR
ENDEC
64 Byte RX FIFO
UART Channel B
(same as Channel A)
Crystal Osc/Buffer
2.25 to 5.5 Volt VCC
GND
TXA, RXA, DTRA#,
DSRA#, RTSA#,
DTSA#, CDA#, RIA#,
OP2A#
TXB, RXB, DTRB#,
DSRB#, RTSB#,
CTSB#, CDB#, RIB#,
OP2B#
XTAL1
XTAL2
2751BLK
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • [phone] • FAX [phone] • www.exar.com