XR16L2750_05 Datasheet, PDF (5/48 Pages) Exar Corporation – 2.25V TO 5.5V DUART WITH 64-BYTE FIFO

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REV. 1.2.1
XR16L2750
2.25V TO 5.5V DUART WITH 64-BYTE FIFO
Pin Description
NAME
44-PLCC
PIN #
48-TQFP
PIN #
TYPE
DESCRIPTION
RXB
10
4
I UART channel B Receive Data or infrared receive data. Normal receive
data input must idle HIGH. The infrared receiver pulses typically idles at
logic 0 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.
RTSB#
27
22
O 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].
CTSB#
28
23
I 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.
DTRB#
38
35
O UART channel B Data-Terminal-Ready (active low) or general purpose
output. If it is not used, leave it unconnected.
DSRB#
25
20
I 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.
CDB#
21
16
I 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.
RIB#
26
21
I 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.
OP2B#
15
9
O 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 LOW when MCR[3] is set to a logic 1. INTB is set to
the three state mode and OP2B# output HIGH when MCR[3] is set to a
logic 0. See MCR[3]. This output should not be used as a general out-
put else it will disturb the INTB output functionality.
ANCILLARY SIGNALS
XTAL1
18
13
I Crystal or external clock input. Caution: this input is not 5V tolerant.
XTAL2
19
14
O Crystal or buffered clock output.
RESET
39
36
I Reset (active high) - A longer than 40 ns HIGH pulse on this pin will
reset the internal registers and all outputs. The UART transmitter output
will be held HIGH, the receiver input will be ignored and outputs are
reset during reset period (see External Reset Conditions).
VCC
44
42
Pwr 2.25V to 5.5V power supply. All input pins, except XTAL1, are 5V toler-
ant.
GND
22
17
Pwr Power supply common, ground.
N.C.
none 12, 24, 25,
37
No Connection.
Pin type: I=Input, O=Output, I/O= Input/output, OD=Output Open Drain.
5