XRT4500 Datasheet, PDF (62/99 Pages) Exar Corporation – MULTIPROTOCOL SERIAL NETWORK INTERFACE IC

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XRT4500
MULTIPROTOCOL SERIAL NETWORK INTERFACE IC
REV. 1.0.7
A system design similar to that presented below in
lationship between another Multi-protocol Transceiver
Figure 32, will accomplish the exact same function/re- IC and the SCC/Microprocessor.
FIGURE 32. AN ILLUSTRATION OF THE NECESSARY GLUE LOGIC REQUIRED TO DESIGN A FEATURE SIMILAR TO THAT
OFFERED BY THE “REGISTERED” MODE, WHEN USING A DIFFERENT MULTI-PROTOCOL SERIAL NETWORK INTERFACE IC
DTE Mode
Serial
Network
Interface Device
D-Flip-Flops
DTR_Signal
Q
CLK
DSR_Signal
Q
CLK
RL_Signal
Q
CLK
RI_Signal
Q
CLK
µC/µP
Clock
Clock Source
1.3.9 The Internal Oscillator
The XRT4500 includes an “Internal Oscillator” that
can be used to support “DTE Stand-Alone Testing/
Diagnostics” operations.
The user can enable the “Internal Oscillator” feature
(within the XRT4500) by pulling the “OSC_EN” input
pin (pin 53) “low”. Conversely, the user can disable
the “Internal Oscillator” feature by pulling the
“OSC_EN” input pin “high”.
If the user enables this feature, then the XRT4500 will
synthesize a clock signal (of frequencies ranging from
32kHz to 64kHz). Further, this clock signal will be out-
put via the “RX2D” and the “RX3D” output pins. Fig-
ure 1.20 presents an illustration of the XRT4500
(while interfaced to the DTE SCC) when the Internal
Oscillator is enabled.
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