ocx256 ETC-unknow, ocx256 Datasheet - Page 22

• Manufacturer Part Number: ocx256
• Description: Ocx256 Crosspoint Switch
• Manufacturer: ETC-unknow

3. Differential I/O Standards
OCX256 Crosspoint Switch—Advanced Datasheet
3.1 LVDS
22
The OCX256 supports the two most popular differential signaling standards: Low Voltage Differential Signaling
(LVDS) and Low Voltage Positive Emitter Coupled Logic (LVPECL).
LVDS is typically used in communication systems as high speed, low noise point-to-point links. The OCX256
conforms to the ANSI/TIA/EIA-644 standard covering electrical specifications for output drivers and receiver
inputs.
LVPECL is commonly used in video switching applications or those designs requiring transmission of high-
speed clock signals.
LVDS is a differential signaling standard. It requires that one data bit is carried through two signal lines.
As with all differential signaling standards, LVDS has an inherent noise immunity over single-ended
standards. The voltage swing between two signal lines is approximately 350mV. The use of a reference
voltage or a board termination voltage is not required. LVDS requires the use of two pins per input or
output. The OCX256L supports LVDS signalling. Integrated Output Attenuator resistors produce the
required LVDS Output swing while providing a 100 ohm output impedance to minimize return reflections.
INN
INP
Z
Z
0
0
=50
=50
110
R
Figure 7
T
[Rev. 2.0] 3/21/02
+
–
OCX256L LVDS Signal Circuit
OCX256L
Device
Switch
Matrix
V
= 2.5V
DD.PAD
Z
Z
0
0
=50
=50
Fairchild Semiconductor
OUTP
OUTN