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Exar Corporation 48720 Kato Road, Fremont CA, 94538 (510) 668-7000 FAX (510) 668-7017 www.exar.com
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XR16C2852
2.97V TO 5.5V DUAL UART WITH 128-BYTE FIFOS
FEBRUARY 2005
REV. 2.1.1
GENERAL DESCRIPTION
The XR16C28521 (2852) is a dual universal
asynchronous receiver and transmitter (UART). The
device operates at 2.97V to 5.5V and is pin-to-pin
compatible to Exar’s ST16C2552 and XR16L2752.
The 2852 register set is compatible to the
ST16C2552 and the XR16L2752 enhanced features.
It supports the Exar’s enhanced features of 128 bytes
of TX and RX FIFOs, programmable FIFO trigger
level and FIFO level counters, automatic hardware
(RTS/CTS) and software flow control, automatic RS-
485 half duplex direction control output and a
complete modem interface. Onboard registers
provide the user with operational status and data
error flags. An internal loopback capability allows
system diagnotics. Independent programmable baud
rate generators are provided in each channel to
select data rates up to 3.125 Mbps at 5V. The 2852 is
available in the 44-pin PLCC package.
NOTE: 1 Covered by U.S. Patent #5,649,122 and #5,949,787
APPLICATIONS
Portable Appliances
Telecommunication Network Routers
Ethernet Network Routers
Cellular Data Devices
Factory Automation and Process Controls
FEATURES
Added feature in devices with a top mark date code of
"F2 YYWW" and newer:
■ 5V tolerant inputs
■ 0 ns address hold time (TAH)
Pin-to-pin compatible to Exar’s ST16C2552 and
XR16L2752
Improved version of PC16C552
Two independent UART channels
■ Register set compatible to 16C550
■ Up to 3 Mbps at 5V, and 2 Mbps at 3.3V
■ Transmit and Receive FIFOs of 128 bytes
■ Programmable TX and RX FIFO Trigger Levels
■ Transmit and Receive FIFO Level Counters
■ Automatic Hardware (RTS/CTS) Flow Control
■ Selectable Auto RTS Flow Control Hysteresis
■ Automatic Software (Xon/Xoff) Flow Control
■ Automatic
RS-485
Half-duplex
Direction
Control Output
■ Wireless Infrared (IrDA 1.0) Encoder/Decoder
■ Automatic sleep mode
Alternate Function Register
Device Identification and Revision
Crystal oscillator or external clock input
2.97 to 5.5 volt operation
Industrial and commercial temperature ranges
FIGURE 1. XR16C2852 BLOCK DIAGRAM
MFA#
(OP2A#,
BAUDOUTA#, or
RXRDYA#)
MFB#
(OP2B#,
BAUDOUTB#, or
RXRDYB#)
XTAL1
XTAL2
Crystal Osc/Buffer
TXA (or TXIRA)
8-bit Data
Bus
Interface
UART Channel A
128 Byte TX FIFO
128 Byte RX FIFO
BRG
IR
ENDEC
TX & RX
UART
Regs
2.97V to 5.5V VCC
GND
UART Channel B
(same as Channel A)
A2:A0
D7:D0
CS#
CHSEL
INTA
INTB
IOW#
IOR#
Reset
TXRDYA#
TXRDYB#
CTS#A/B, RI#A/B,
CD#A/B, DSR#A/B
RXA (or RXIRA)
Modem Control Logic
DTR#A/B, RTS#A/B
TXB (or TXIRB)
RXB (or RXIRB)