xr16c2550ip Exar Corporation, xr16c2550ip Datasheet - Page 7

• Manufacturer Part Number: xr16c2550ip
• Description: Dual Uart With 16-byte Transmit And Receive Fifos
• Manufacturer: Exar Corporation

xr
REV. 1.0.1
The CPU interface is 8 data bits wide with 3 address lines and control signals to execute data bus read and
write transactions. The 2550 data interface supports the Intel compatible types of CPUs and it is compatible to
the industry standard 16C550 UART. No clock (oscillator nor external clock) is required to operate a data bus
transaction. Each bus cycle is asynchronous using CS#, IOR# and IOW# signals. Both UART channels share
the same data bus for host operations. The data bus interconnections are shown in
.
The RESET input resets the internal registers and the serial interface outputs in both channels to their default
state (see
function in the device.
The UART provides the user with the capability to bi-directionally transfer information between an external
CPU and an external serial communication device. A logic 0 on chip select pins, CSA# or CSB#, allows the
user to select UART channel A or B to configure, send transmit data and/or unload receive data to/from the
UART. Selecting both UARTs can be useful during power up initialization to write to the same internal registers,
but do not attempt to read from both uarts simultaneously. Individual channel select functions are shown in
Table
2.0 FUNCTIONAL DESCRIPTIONS
2.1
2.2
2.3
1.
CPU Interface
Device Reset
Channel A and B Selection
Table
F
IGURE
UART_RESET
UART_CSA#
UART_CSB#
UART_INTA
UART_INTB
11). An active high pulse of at least 40 ns duration will be required to activate the reset
RXRDYA#
RXRDYB#
TXRDYA#
TXRDYB#
3.
IOW#
IOR#
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
XR16C2550 D
CSA#
1
0
1
0
T
ABLE
ATA
B
1: C
CSB#
US
1
1
0
0
HANNEL
I
NTERCONNECTIONS
7
Channel A and B selected
A
IOR#
IOW#
CSA#
CSB#
RESET
D0
D1
D2
D3
D4
D5
D6
D7
INTA
INTB
TXRDYA#
RXRDYA#
TXRDYB#
RXRDYB#
A0
A1
A2
AND
Channel A selected
Channel B selected
UART de-selected
B S
F
2.97V TO 5.5V DUART WITH 16-BYTE FIFO
UNCTION
Channel A
Channel B
UART
UART
ELECT
DTRA#
DSRA#
DTRB#
DSRB#
RTSA#
CTSA#
RTSB#
CTSB#
OP2A#
CDA#
OP2B#
CDB#
GND
VCC
RIA#
RIB#
TXA
RXA
TXB
RXB
VCC
Serial Interface of RS-
Serial Interface of
RS-232, RS-485
232, RS-485
Figure
3.
2750int
XR16C2550