xr16m2651 Exar Corporation, xr16m2651 Datasheet - Page 8

• Manufacturer Part Number: xr16m2651
• Description: High Performance Duart With 32-byte Fifo And Powersave Feature
• Manufacturer: Exar Corporation

XR16M2651
HIGH PERFORMANCE DUART WITH 32-BYTE FIFO AND POWERSAVE FEATURE
The CPU interface is 8 data bits wide with 3 address lines and control signals to execute data bus read and
write transactions. The M2651 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 CSA/B#, IOR# and IOW# or CS#, R/W# and A3 inputs.
Both UART channels share the same data bus for host operations. A typical data bus interconnection for Intel
and Motorola mode is 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.
F
2.0 FUNCTIONAL DESCRIPTIONS
2.1
2.2
IGURE
3. XR16M2651 T
CPU Interface
Device Reset
Table
U ART_RESET#
UAR T_C SA#
UAR T_C SB#
UAR T_R ESET
UAR T_IR Q #
U ART_INTA
U ART_INTB
UAR T_C S#
RXR D YA#
RXR D YB#
TXR DYA#
TXR DYB#
RXR D YA#
RXR D YB#
TXR DYA #
TXR DYB #
16). An active high pulse of longer than 40 ns duration will be required to activate the reset
IO W #
R /W #
IO R #
A0
A1
A2
D 0
D 1
D 2
D 3
D 4
D 5
D 6
D 7
A0
A1
A2
A3
D 0
D 1
D 2
D 3
D 4
D 5
D 6
D 7
YPICAL
Figure
I
NTEL
/M
M otorola Data Bus Interconnections
3.
Intel Data Bus Interconnections
OTOROLA
VCC
(no connect)
VCC
D
ATA
8
B
TXRDYA#
R XRD YA#
TXRDYB#
R XRD YB#
IO R #
IO W #
C SA#
C SB#
INTA
INTB
RESET
TXRD YA#
R XRD YA#
TXRD YB#
R XRD YB#
D 0
D 1
D 2
D 3
D 4
D 5
D 6
D 7
C SB#
IO R #
IO W #
CSA#
IN TA
IN TB
A 0
A 1
A 2
R ESET#
US
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
I
NTERCONNECTIONS
Channel A
Channel B
C hannel A
C hannel B
UAR T
UAR T
U ART
U ART
D TR B #
D SRB#
D TR A#
DSR A#
O P2A#
D TR B#
DSR B#
O P2B#
D SRA#
O P2A#
R TSB#
C TSB#
O P2B#
RTSA#
CTSA#
RTSB#
CTSB#
DTRA#
R TSA#
C TSA#
C DA#
C DB#
C D A#
CD B#
RIA#
RIB#
G N D
RIA#
G ND
TXB
RXB
RIB#
TXA
R XA
TXB
R XB
VCC
VC C
TXA
RXA
VC C
2.25 to 3.6 Volt VC C
(no connect)
(no connect)
(no connect)
(no connect)
Serial Interface of
Serial Interface of
Serial Interface of
Serial Interface of
RS-232, R S-422
RS-232, R S-422
R S-232, RS-422
R S-232, RS-422
REV. 1.0.2