XRT4500 Datasheet, PDF (11/99 Pages) Exar Corporation – MULTIPROTOCOL SERIAL NETWORK INTERFACE IC

XRT4500
MULTIPROTOCOL SERIAL NETWORK INTERFACE IC
REV. 1.0.7
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PIN DESCRIPTIONS (CONT.)
PIN
Signal
#
18
LP
19
TX8O
20
VDD
21
CPP
22
CPM
DTE
MODE
RLA
DCE
MODE
TYPE FUNCTION
I Loopback Command Input Pin – Active Low:
This active-low input pin permits the user to configure the
XRT4500 into a “Loop-Back” Mode. The exact loop-back will
depend upon whether the XRT4500 is operating in the DTE or
DCE Modes.
Setting this input pin to “LOW” enables the Loop-back Operation.
Setting this input pin to “HIGH” disables the Loop-back Operation.
This input pin contains an Internal 20KΩ pull-up to VDD.
RIA
O Transmitter 8 – Single Ended Data Output to Line
The XRT4500 accepts a TTL level binary data stream, from the
local terminal equipment via the “TX8D” input pin (pin 17), and
outputs it, in either a V.10 or V.28 manner via this output pin. The
exact role that this output pin plays depends upon whether the
XRT4500 is operating in the DTE or DCE Modes.
If the XRT4500 is configured to operate in the DCE Mode:
This output pin will typically drive the state of either the “RI”
(Ring Indicator) or “TM” (Test Mode) signals to the Remote
Terminal Equipment.
If the XRT4500 is configured to operate in the DTE Mode:
This output pin will typically drive the state of the “RL” (Remote
Loop-back) signal to the Remote Terminal Equipment.
Analog VDD – For Receivers 4, 5, 6, 7 and 8.
Charge Pump Capacitor Pin: A 2.2µF tantalum capacitor must
be connected between pin 21 and pin 22.
Charge Pump Capacitor Pin: A 2.2µF tantalum capacitor must
be connected between pin 21 and pin 22.
NOTE: Signal names beginning with D_ are digital signals.
NOTE: Signal names ending with B and A are the positive
and negative polarities of differential signals respectively.
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