xr16c2850im Exar Corporation, xr16c2850im Datasheet - Page 5

• Manufacturer Part Number: xr16c2850im
• Description: Dual Uart With Tx And Rx Fifo Counters, 128 Bytes Of Fifos And Automatic Rs-485 Half Duplex Control
• Manufacturer: Exar Corporation

xr
REV. 2.1.3
ANCILLARY SIGNALS
HDCNTL#
DSRB#
RTSB#
CTSB#
DTRB#
OP2B#
XTAL1
XTAL2
CDB#
N
RIB#
RXB
AME
44-PLCC
P
10
27
28
38
25
21
26
15
18
19
IN
-
#
48-TQFP
P
22
23
35
20
16
21
13
14
37
IN
4
9
#
T
YPE
O
O
O
O
I
I
I
I
I
I
I
UART channel B Receive Data or infrared receive data. Normal receive
data input must idle HIGH. The infrared receiver pulses typically idles
LOW but can be inverted by software control prior going in to the
decoder, see MCR[6] and FCTR[2]. If this pin is not used, tie it to VCC
or pull it high via a 100k ohm resistor.
UART channel B Request-to-Send (active low) or general purpose out-
put. This port must be asserted prior to using auto RTS flow control,
see EFR[6], MCR[1], FCTR[1:0], EMSR[5:4] and IER[6]. For auto
RS485 half-duplex direction control, see FCTR[3] and EMSR[3]. If this
output is not used, leave it unconnected.
UART channel B Clear-to-Send (active low) or general purpose input.
It can be used for auto CTS flow control, see EFR[7], and IER[7]. This
input should be connected to VCC when not used.
UART channel B Data-Terminal-Ready (active low) or general purpose
output. If this output is not used, leave it unconnected.
UART channel B Data-Set-Ready (active low) or general purpose input.
This input should be connected to VCC when not used. This input has
no effect on the UART.
UART channel B Carrier-Detect (active low) or general purpose input.
This input should be connected to VCC when not used. This input has
no effect on the UART.
UART channel B Ring-Indicator (active low) or general purpose input.
This input should be connected to VCC when not used. This input has
no effect on the UART.
Output Port 2 Channel B - The output state is defined by the user and
through the software setting of MCR[3]. INTB is set to the active mode
and OP2B# output is LOW when MCR[3] is set to a logic 1. INTB is set
to the three state mode and OP2B# is HIGH when MCR[3] is set to a
logic 0. See MCR[3]. This output can only be used as a general pur-
pose output when interrupts are not used, otherwise it will disturb the
INTB output functionality. If this output is not used, leave it uncon-
nected.
Crystal or external clock input.
Crystal or buffered clock output.
RS-485 half duplex directional control for channel A and B (active low).
Connect to VCC for normal RTS# function and connect to GND for RS-
485 half duplex direction control. RTS# pin goes LOW for transmit and
HIGH for receive during RS-485 mode. This pin is wire “OR-ed” with
FCTR[3]. If this pin is connected to VCC, the function of the RTS# pin
can be controlled via FCTR[3]. If this pin is connected to GND, the
RTS# pin will always be the RS-485 half duplex direction control and
can not be controlled via FCTR[3]. See FCTR[3].
5
2.97V TO 5.5V DUAL UART WITH 128-BYTE FIFOS
D
ESCRIPTION
XR16C2850