GA100358SCILF Integrated Circuit Systems, Inc., GA100358SCILF Datasheet - Page 9

• Manufacturer Part Number: GA100358SCILF
• Description: IC FANOUT BUFFER SINGLE 8TSSOP TUBE
• Manufacturer: Integrated Circuit Systems, Inc.

T
The clock layout topology shown below is a typical termina-
tion for LVPECL outputs. The two different layouts mentioned
are recommended only as guidelines.
FOUT and nFOUT are low impedance follower outputs that gen-
erate ECL/LVPECL compatible outputs. Therefore, terminating
resistors (DC current path to ground) or current sources must
be used for functionality. These outputs are designed to drive
T
This section shows examples of 5V LVPECL output termina-
tion. Figure 4A shows standard termination for 5V LVPECL. The
termination requires matched load of 50 resistors pull down to
853001AG
RTT =
ERMINATION FOR
ERMINATION FOR
F
IGURE
5V
((V
F
FOUT
OH
IGURE
4A. S
PECL
+ V
OL
Integrated
Circuit
Systems, Inc.
3A. LVPECL O
) / (V
TANDARD
1
Zo = 50 Ohm
Zo = 50 Ohm
3.3V LVPECL O
5V LVPECL O
CC
Z
Z
– 2)) – 2
o
o
= 50
= 50
5V PECL O
R1
50
Z
o
50
UTPUT
3V
UTPUT
T
UTPUT
R2
50
RTT
ERMINATION
UTPUTS
50
www.icst.com/products/hiperclocks.html
T
V
ERMINATION
+
-
CC
5V
FIN
- 2V
PECL
9
50 transmission lines. Matched impedance techniques should
be used to maximize operating frequency and minimize signal
distortion. Figures 3A and 3B show two different layouts which
are recommended only as guidelines. Other suitable clock lay-
outs may exist and it would be recommended that the board
designers simulate to guarantee compatibility across all printed
circuit and clock component process variations.
V
lence of Figure 4A. In actual application where the 3V DC power
supply is not available, this approached is normally used.
CC
2.5V, 3.3V, 5V LVPECL/ECL B
F
- 2V = 3V at the receiver. Figure 4B shows Thevenin equiva-
IGURE
FOUT
5V
F
IGURE
4B. 5V PECL O
PECL
1:1, D
3B. LVPECL O
Zo = 50 Ohm
Zo = 50 Ohm
Z
Z
o
o
= 50
= 50
IFFERENTIAL
125
UTPUT
84
5V
R3
84
UTPUT
R1
125
T
3.3V
ERMINATION
ICS853001
R4
84
125
84
T
R2
125
ERMINATION
LVPECL-
REV. A JANUARY 29, 2005
FIN
+
-
E
XAMPLE
UFFER
PECL
TO
-