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Pin Description
N
AME
RXRDYA#
TXRDYB#
RXRDYB#
48-TQFP
P
IN
#
31
6
18
T
YPE
O
O
O
XR16L2751
2.25V TO 5.5V DUART WITH 64-BYTE FIFO AND POWERSAVE
REV. 1.0.0
D
ESCRIPTION
UART channel A Receiver Ready (active low). This output provides the RX FIFO/
RHR status for receive channel A.
UART channel B Transmitter Ready (active low). The output provides the TX FIFO/
THR status for transmit channel B.
UART channel B Receiver Ready (active low). This output provides the RX FIFO/
RHR status for receive channel B.
MODEM OR SERIAL I/O INTERFACE
TXA
7
O
UART channel A Transmit Data or infrared encoder data. Standard transmit and
receive interface is enabled when MCR[6] = 0. In this mode, the TX signal will be a
logic 1 during reset or idle (no data). Infrared IrDA transmit and receive interface is
enabled when MCR[6] = 1. In the Infrared mode, the inactive state (no data) for the
Infrared encoder/decoder interface is a logic 0. If it is not used, leave it unconnected.
UART channel A Receive Data or infrared receive data. Normal receive data input
must idle at logic 1 condition. The infrared receiver pulses typically idles at logic 0 but
can be inverted by software control prior going to the decoder, see MCR[6] and
FCTR[2].
UART channel A Request-to-Send (active low) or general purpose output. This out-
put 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].
UART channel A Clear-to-Send (active low) or general purpose input. It can be used
for auto CTS flow control, see EFR[7], MSR[4] and IER[7]. This input should be con-
nected to VCC when not used.
UART channel A Data-Terminal-Ready (active low) or general purpose output.
UART channel A 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 A 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 A 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 A - The output state is defined by the user and through the
software setting of MCR[3]. When MCR[3] is set to a logic 1, INTA is set to the level
mode and OP2A# output to a logic 0. When MCR[3] is set to a logic 0, INTA is set to
the three state mode and OP2A# to a logic 1. See MCR[3]. This output must not be
used as a general output when the interrupt output is used else it will disturb the INTA
output functionality.
UART channel B Transmit Data or infrared encoder data. Standard transmit and
receive interface is enabled when MCR[6] = 0. In this mode, the TX signal will be a
logic 1 during reset or idle (no data). Infrared IrDA transmit and receive interface is
enabled when MCR[6] = 1. In the Infrared mode, the inactive state (no data) for the
Infrared encoder/decoder interface is a logic 0. If it is not used, leave it unconnected.
RXA
5
I
RTSA#
33
O
CTSA#
38
I
DTRA#
DSRA#
CDA#
RIA#
OP2A#
34
39
40
41
32
O
I
I
I
O
TXB
8
O
4
EXAR [ EXAR CORPORATION ]
