SD346EVK National Semiconductor, SD346EVK Datasheet - Page 5

• Manufacturer Part Number: SD346EVK
• Description: BOARD EVAL LMH0346
• Manufacturer: National Semiconductor

Specifications of SD346EVK

• Main Purpose: Video, HD/SD SDI Reclocker
• Utilized Ic / Part: LMH0346
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -

There is also a header on the right side of the SD346EVK board which is connected to the SD/HD
indication of the LMH0346SQ SDI Reclocker. It is meant to control an LMH0302 SDI cable driver. The
output polarity of the signal on this header is such that it can be connected directly to the SD/HD control
input of the LMH0302 cable driver. The header on the SD346EVK board facilitates this connection.
27 MHz Reference
The SD346EVK includes an on-board 27-MHz reference crystal. In the normal configuration of the board
this crystal is active. The LMH0346SQ SDI Reclocker includes a crystal driver circuit that produces the
27-MHz reference clock using this crystal.
The SD346EVK also includes a connector for inputting an external 27-MHz reference if desired. In order
to disable the on-board crystal a 0Ω resistor indicated on the schematic for the board must be removed.
This permits evaluation of the operation of the LMH0346SQ SDI Reclocker with an external reference.
SMBus Connector
The LMH0346SQ SDI Reclocker can be controlled via a 2-wire bus very similar to the standard SMBus.
This mode of operation was designed for factory use only.
Typical Output Waveform
A test waveform can be readily generated and used to verify proper operation of the SD346EVK. In order
to generate this output waveform, the following setup procedure should be used.
Test Setup
The test setup used for testing the SD346EVK board is shown in Figure 2. Note that the test setup
includes a SyntheSys Research BERTScope as a signal generator, eye diagram measurement device,
and bit error rate test receiver. Other equivalent instruments could be used for these measurements.
The equipment used for testing the SD346EVK is listed in Table 2.
SD346EVK User Manual
5 of 10
Rev 1.0
© 2008, National Semiconductor Corp.