ICS889831 Datasheet, PDF (13/18 Pages) Integrated Circuit Systems – LOW SKEW, 1-TO-4 DIFFERENTIAL LVPECL-TO-LVPECL/ECL FANOUT BUFFER

Integrated
Circuit
Systems, Inc.
ICS889831
LOW SKEW, 1-TO-4
DIFFERENTIAL LVPECL-TO-LVPECL/ECL FANOUT BUFFER
SCHEMATIC EXAMPLE
Figure 8 shows a schematic example of the ICS889831. This
schematic provides examples of input and output handling. The
ICS889831 input has built-in 50Ω termination resistors. The in-
put can directly accept various types of differential signal with-
out AC couple. For AC couple termination, the ICS889831 also
provides the VREF_AC pin for proper offset level after the AC
couple. This example shows the ICS889831 input driven by a
2.5V LVPECL driver with AC couple. The ICS889831 outputs
are LVPECL driver. In this example, we assume the traces are
long transmission line and the receiver is high input impedance
without built-in matched load. An example of 3.3V LVPECL ter-
mination is shown in this schematic. Additional termination ap-
proaches are shown in the LVPECL Termination Application Note.
2.5V
LVPECL
R1
100
Zo = 50
Zo = 50
R2
100
C2
3.3V
0.1u
U1
ICS889831
C5
9
10
11
12
nIN
VREF_AC
VT
IN
C6
4
nQ2
Q2
nQ1
Q1
3
2
1
3.3V
C1
0.1u
Zo = 50
Zo = 50
3.3V
R3
R5
133
133
R4
82. 5
R6
82.5
3.3V
-
+
Zo = 50
Zo = 50
3.3V
R7
R9
133
133
R8
82. 5
R10
82.5
3.3V
-
+
FIGURE 8. ICS889831 APPLICATION SCHEMATIC EXAMPLE
889831AK
www.icst.com/products/hiperclocks.html
13
REV. A JUNE 16, 2005