參數(shù)資料
型號(hào): Am7968-125DKC
廠商: Advanced Micro Devices, Inc.
英文描述: TAXIchip Integrated Circuits(Transparent Asynchronous Xmitter-Receiver Interface)
中文描述: TAXIchip集成電路(透明異步Xmitter,接收器接口)
文件頁數(shù): 99/127頁
文件大?。?/td> 730K
代理商: AM7968-125DKC
95
TAXIchip Integrated Circuits Technical Manual
T AX I T IPs
TAXI T
echnical
I
nformation
P
ublication
#89-01
S ubjec t: Rec eiver Response to Loss of Input S ignal
Question:
It is desired that the TAXI Receiver outputs be predictable and stable during conditions
when the TAXI Transmitter may cease transmitting (power-off) or is disconnected. How
can a system designer predict the TAXI Receiver outputs or use the TAXI Receiver in a
system where the TAXI Receiver must appear Inactiveunder these conditions This
applies to both Coaxial and Fiber-Optic Systems.
Answer:
The key to this problem is interpreting the loss of incoming Tx data as a Quiet-Line-
State and either flagging the system accordingly or gating the TAXI Receiver outputs
with an inactiveflag.
In a Coaxial coupled system the loss of incoming signal drive will cause the TAXI
Receiver inputs to rest at the input termination bias voltages. The differential serial
inputs will normally be at equal potential. To properly interpret a loss of signal as a
constant quietstate the input termination bias voltages must be altered slightly from
each other. To allow reliable interpretation of the offset as a constant logic state, the
offset voltage should typically be set to about 50 mV.
The TAXI Receiver will interpret the Quiet-Line-State differently depending upon the
operation mode (8-bit, 9-bit, or 10-bit). In 8-bit mode the Receiver will generate continu-
ous CSTRB’s with the Command outputs at F Hex, or all HIGH. In the 9-bit and 10-bit
modes there is no defined interpretation of an incoming quiet data stream. This will
cause the TAXI Receiver to generate continuous CSTRB’s and the Violation output will
be continuously HIGH. A one-shot may be used to determine Violation=HIGH duration
and then generate an inactiveflag, or the system may interpret the Violation output
directly as an inactiveor invalidcondition flag and halt data-dependent system opera-
tions during any byte with Violation=HIGH.
In a Fiber-Optic coupled system two methods may be used, depending on the Optical
Receiver construction. If the Optical Receiver has a Carrier-Detect output this signal
may be used to flag an inactive state. If there is no Carrier-Detect, one may be gener-
ated using an ECL one shot arrangement which will detect loss of edges after a
predetermined period of say, for example, 80 bit times. The actual time may vary
depending on the desired response to loss of data.
In either condition, if the Receiver recovered Byte Clock (CLK) is used as a system
clock, then the system must be able to tolerate a shift in the CLK frequency of typically
about +/-3% to allow for Rx-PLL offset and drift during this period. (If the Optical
Receiver begins oscillation when the fiber is dark, the TAXI Receiver PLL may attempt
to track the oscillation resulting in an indeterminate Rx recovered clock frequency.
Optical Receiver dark response thus becomes a possible system concern.)
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AM7968-125DMC 制造商:AMD 制造商全稱:Advanced Micro Devices 功能描述:TAXIchip Integrated Circuits(Transparent Asynchronous Xmitter-Receiver Interface)
AM7968-125JC 制造商:Advanced Micro Devices 功能描述: 制造商:Rochester Electronics LLC 功能描述:
AM7968-125JCB 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Transmitter
AM7968-125JC-G 制造商:Rochester Electronics LLC 功能描述:- Bulk
AM7968-125LE 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Transmitter