XR16L651 Datasheet, PDF (8/56 Pages) Exar Corporation – 2.25V TO 5.5V UART WITH 32-BYTE FIFO

XR16L651
2.25V TO 5.5V UART WITH 32-BYTE FIFO
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REV. 1.3.0
2.0 FUNCTIONAL DESCRIPTIONS
2.1 Host Data Bus Interface
The host interface is 8 data bits wide with 3 address lines and control signals to execute bus read and write
transactions. The 651 supports 3 type of host interfaces: Intel, Motorola and PC mode. The Intel and Motorola
interfaces provide support for their respective microcontroller or processor. This facilitates the hardware design
and interconnections. The Intel bus interface is selected by connecting IM# to logic 0 and PCMODE# to logic 1.
The Intel bus interconnections are shown in Figure 3. The Motorola bus is selected with the IM# input
connected to logic 1 and PCMODE# input ties to logic 1. The Motorola bus interconnections are shown in
Figure 4. The special PC mode is selected when IM# and PCMODE# are connected to logic 0. The PC mode
interconnections are shown in Figure 5.
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FIGURE 3. XR16L651 INTEL BUS INTERCONNECTIONS
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
IO R *
IOW *
CS#
IN T
RESET
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
IO R #
IOW #
CS2#
IN T
BAUDOUT#
RCLK
VCC
CS0
CS1
PCMODE#
IM #
TX
RX
DTR#
RTS#
CTS#
DSR#
CD#
R I#
RESET
OP1#
OP2#
IO W
IO R
AS#
GND
VCC
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