ICS858020 Datasheet, PDF (9/14 Pages) Integrated Device Technology – LOW SKEW, 1-TO-4 DIFFERENTIAL-TO-CML FANOUT BUFFER

ICS858020
LOW SKEW, 1-TO-4
DIFFERENTIAL-TO-CML FANOUT BUFFER
SCHEMATIC EXAMPLE
Figure 3 shows a schematic example of the ICS858020. This
schematic provides examples of input and output handling. The
ICS858020 input has built-in 50Ω termination resistors. The in-
put can directly accept various types of differential signal with-
out AC couple. If AC couple termination is used, the ICS858020
also provides VREF_AC pin for proper offset level after the AC
couple. This example shows the ICS858020 input driven by a
2.5V LVPECL driver with AC couple. The ICS858020 outputs
are CML driver with built-in 50Ω pull up resistors. In this ex-
ample, we assume the traces are long transmission line and the
receiver is high input impedance without built-in matched load.
An external 100Ω resistor across the receiver input is required.
3.3V
2.5V
LVPECL
Zo = 50
Zo = 50
R1
R2
100
100
U1
ICS858020
C5
1
2
3
IN
VT
4 ^VREF_AC
nIN
C6
3.3V
C1
0.1u
12
Q1
nQ1
11
10
Q2
nQ2
9
3.3V
C2
0.1u
Zo = 50
+
R3
Zo = 50 100
-
100 Ohm Dif f erential
Zo = 50
R4
Zo = 50 100
100 Ohm Dif f erential
3.3V
+
-
FIGURE 3. ICS858020 APPLICATION SCHEMATIC EXAMPLE
858020AK
9
REV. A DECEMBER 10, 2007