EXAR Corporation, 48720 Kato Road, Fremont, CA 94538 • (510) 668-7000 • FAX (510) 668-7017
XR16C2850
Rev. 1.00P
PLCC Package
DUAL UART WITH 128-byte FIFO s AND
RS-485 HALF DUPLEX CONTROL
DESCRIPTION
The XR16C2850 (2850) is a dual universal asynchronous receiver and transmitter (UART). The 2850 provides
enhanced UART functions with 128 byte FIFO, automatic RS-485 half duplex control, a modem control interface,
and data rates up to 1.5 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. An internal loopback capability allows onboard diagnostics. Independent programmable baud rate
generators are provided to select transmit and receive clock rates up to 1.5 Mbps. The baud rate generator can
be configured for either crystal or external clock input. The 2850 is available in a 40-pin PDIP, 44-pin PLCC, and
48-pin TQFP packages. The 40 pin package does not offer TXRDY and RXRDY pins (DMA Signal monitoring).
Otherwise the three package versions are the same. The 2850 is functionally compatible with the ST16C2550.
The 2850 is fabricated in an advanced CMOS process to achieve low drain power and high speed requirements.
FEATURES
• Pin and functionally compatible to ST16C2550,
software compatible with INS8250, NS16C550
• 1.5 Mbps transmit/receive operation (24 MHz
Max.).
• 128 byte transmit FIFO to reduce bandwidth re-
quirement of the external CPU.
• 128 byte receive FIFO with error flags to reduce
bandwidth requirement of the external CPU.
• Independent transmit and receive UART control.
• RS-485 half duplex control.
• Programmable transmit/receive FIFO trigger lev-
els.
• Hardware / software flow control.
• Selectable RTS flow control hysterisis.
• Modem control signals (-CTS, -RTS, -DSR, -DTR,
-RI, -CD, and software controllable line break).
• Programmable character lengths (5, 6, 7, 8) with
even, odd, or no parity.
• Infrared receive and transmit encoder/decoder.
• Device identification.
• Crystal or external clock input.
• 460.8 Kbps transmit/receive operation with 7.3728
MHz crystal or external clock source.
ORDERING INFORMATION
Part number Pins Package Operating temperature
XR16C2850CP 40 PDIP 0 C to + 70 C
XR16C2850CJ 44 PLCC 0 C to + 70 C
XR16C2850CM 48 TQFP 0 C to + 70 C
Part number Pins Package Operating temperature
XR16C2850IP 40 PDIP -40 C to + 85 C
XR16C2850IJ 44 PLCC -40 C to + 85 C
XR16C2850IM 48 TQFP -40 C to + 85 C
6 5 4 3 2 1
44 43 42 41 40
7
8
9
10
11
12
13
14
15
16
17
39
38
37
36
35
34
33
32
31
30
29
18 19 20 21 22 23 24 25 26 27 28
D5
D6
D7
RXB
RXA
-TXRDYB
TXA
TXB
-OPB
-CSA
-CSB
RESET
-DTRB
-DTRA
-RTSA
-OPA
-RXRDYA
INTA
INTB
A0
A1
A2
XT
A
L
1
XT
A
L
2
-I
OW
-C
D
B
GN
D
-
R
X
RDY
B
-I
OR
-D
S
R
B
-R
I
B
-R
T
S
B
-C
T
S
B
D4 D3 D2 D1 D0 -T
X
R
D
Y
A
VC
C
-R
I
A
-C
D
A
-D
S
R
A
-C
T
S
A
XR16C2850CJ
Preliminary
Information