參數(shù)資料
型號: AM7968-125VB3A
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): 67/127頁
文件大?。?/td> 730K
代理商: AM7968-125VB3A
AMD
63
TAXIchip Integrated Circuits Technical Manual
level of the optical components must match those of the TAXIchip set in order for the DC
connection to work. If the supply voltage or the logic levels are incompatible, an AC
connection must be used.
5.2 T erminated, DC Coupled
The parallel termination shown in Figure 5-2 may be used for a DC connection of a TAXI
Transmitter to a TAXI Receiver. The parallel termination provides both the line termina-
tion (R1llR2 =
Z0
= line characteristic impedance) and a pull-down voltage. The Thevenin
equivalent of this termination is Z0 pulled down to V
CC
–2 V, assuring both matched
termination and adequate V
OL
. Using V
CC
and a voltage divider provides pull-down
voltage without the need for a separate power supply.
Figure 5-2
Parallel T ermination
R2
12330E-9
V
CC
R1
R2 (R1 + R2) V
CC
= V
CC
– 2 V
R
1
| / R
2
= Z
0
Thevenin
Equivalent
R2
V
CC
R1
SERIN
TAXI RX
SEROUT
TAXI TX
Pseudo-ECL
Driver
Copper Media
Z0
5.3 T erminated, AC Coupled
AC coupling is the connection of choice for many TAXIchip set applications. The typical
arrangement for an AC coupled link is shown in Figure 5-3. RE is returned to ground to
provide the PECL (pseudo-ECL) pull-down for the driver. The capacitor C blocks the DC
voltage, and R1 and R2 terminate the transmission line and provide a DC bias level for
the Receiver. Since only AC variations are passed through the coupling capacitor, the
bias level at the termination should be set to the midpoint of the signal swing expected
by the Receiver input stage. Note that this bias level is not the same as that which is
recommended for the DC coupled case.
The minimum value of RE was previously established as 186
, to avoid exceeding
I
OH
max. The maximum value of RE must be small enough to supply the transmission
line with enough current to avoid cutting off the output driver. When switching from a
HIGH to the LOW state, the transmission line may cause the emitter voltage of the driver
to fall more slowly than the base voltage, causing the output transistor to turn off. When
the output transistor turns off, its output impedance becomes very high, causing the
falling edge rate to be controlled by the external load (RE and the transmission line).
This variation in edge rate cannot be tolerated until the falling edge crosses the
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AM7968-125VBXA 制造商:AMD 制造商全稱:Advanced Micro Devices 功能描述:TAXIchip Integrated Circuits(Transparent Asynchronous Xmitter-Receiver Interface)
AM7968-175DC 制造商:Rochester Electronics LLC 功能描述:
AM7968-175DCB 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Transmitter
AM7968-175DKC 制造商:AMD 制造商全稱:Advanced Micro Devices 功能描述:TAXIchip Integrated Circuits(Transparent Asynchronous Xmitter-Receiver Interface)
AM7968-175DMC 制造商:AMD 制造商全稱:Advanced Micro Devices 功能描述:TAXIchip Integrated Circuits(Transparent Asynchronous Xmitter-Receiver Interface)