LVDSEVAL-001 National Semiconductor, LVDSEVAL-001 Datasheet - Page 10

• Manufacturer Part Number: LVDSEVAL-001
• Description: EVALUATION BOARD FOR DS90LV031A
• Manufacturer: National Semiconductor

Specifications of LVDSEVAL-001

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: *LVDSEVAL-001

Option 6: Receiver Termination (Channel #5)
The separate receiver input signals can be terminated separately (50 Ohm on each line to ground) utiliz-
ing pads RT5 (true input to ground) and RT6 (inverting to ground) for a signal generator interface. Or
with a single 100 Ohm differential resistor (pad RL5) if the device is to be driven by a differential driver.
6.1.8 Plug & Play
The following simple steps should be taken to begin testing on your completed evaluation board:
1) Connect signal common (Ground) to the black binding post
2) Connect the power supply lead to the red binding post (5V or 3.3V)
3) Set J1 & J2 jumpers to ground (-) to enable the drivers and receivers
4) Connect a signal generator to the driver input (I4) with:
5) Connect high impedance probes to test points A4 and B4
6) View LVDS signals using the same voltage offset and volts/div settings on the scope with high imped-
6.1.9 Common Mode Noise
When the receivers (DS90C032, DS90LV032) are enabled common mode noise is passed from the output
of the receiver to the inputs. This noise shows up on the single-ended waveforms, but does not impact
the differential waveform that carries the data. For improved signal fidelity a design improvement is
under way to reduce the magnitude of the noise coupled back to the inputs. This noise will not be
observed if the receiver device is disabled by setting J2 to “+”.
6.1.10 Summary
This evaluation PCB provides a simple tool to evaluate LVDS signaling across different media and
lengths to determine signal quality for data transmission applications.
Devices (D/R)
DS90C031/2
DS90LV031/2
DS90LV031A/2A
DS26C31/2A
DS26LV31/2A
ance probes. View the output signal on a separate channel from test point O4.
a) frequency = 50 Mhz (100 Mbps)
b) V
c) t r & t f = 2 ns
d) duty cycle = 50% (square wave)
IL
= 0V & V
IH
= 3.0V
Power Supply
3.3V
3.3V
3.3V
5V
5V
Signaling Levels
LVDS Signals
LVDS Signals
FAST LVDS (planned devices)
RS-422 Signals
RS-422 Signals
LVDS Owner’s Manual
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