LVDS001EVK National Semiconductor, LVDS001EVK Datasheet - Page 5

• Manufacturer Part Number: LVDS001EVK
• Description: BOARD EVALUATION DS90LV001
• Manufacturer: National Semiconductor

Specifications of LVDS001EVK

• Main Purpose: Interface, LVDS, Repeater
• Utilized Ic / Part: DS90LV001
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -

Probing of High Speed LVDS Signals
Probe specifications for measuring LVDS signals are unique due to the low drive level of LVDS (3 mA typical).
For this board design, either a 50 Ohm scope module (SD-22) or the TEK P6247 differential probe (>1 GHz
bandwidth) must be used. The capacitive loading of the probe should be kept in the low pF range, and the
bandwidth of the probe should be at least 1 GHz (4 GHz preferred) to accurately acquire the waveform under
measurement.
National’s Interface Applications group employs a wide range of probes and oscilloscopes. One system that
meets the requirements of LVDS particularly well is an Agilent 86100A Wide-Bandwidth Oscilloscope (>20GHz
bandwidth), Agilent 86112 20GHz module and TEK P6247 differential probe heads. The probe offers 200k ,
1pF loading and a bandwidth of 1GHz. This test equipment was used to acquire the waveforms shown in
Figure 6.
50
DS90LV047A
Figure 6: Input and Output LVDS Signals in Cable Repeater Application
V
CC
Signal 1
DIFF OUT± DS90LV047A
EN
10 meter CAT5 cable
100
IN-
IN+
Signal 2
DIFF IN± J2
J2
+
_
DS90LV001
V
CC
EN
100
Signal 3
DIFF OUT± J3
J3
5