SD346EVK National Semiconductor, SD346EVK Datasheet - Page 3

• 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: -

Although the SMA coaxial connectors are ruggedized for attachment to the edge of the SD346EVK PC
board, they can be damaged by over-tightening them. A standard SMA torque wrench with a torque
limitation of 7-10 in-pounds should always be used to connect cables to the connectors on the
SD346EVK. Do not allow heavy cables to hang unsupported from the connectors as they may break off
the board.
The SDI input and output connectors occur in pairs as the input and the outputs of the LMH0346SQ SDI
Reclocker are differential. The outputs of the LMH0346SQ SDI Reclocker are internally terminated. The
input to the LMH0346SQ Reclocker is externally terminated on the SD346EVK board with a 100Ω
differential resistor.
The SD346EVK has two sets of outputs connected to the two outputs of the LMH0346SQ SDI Reclocker.
The first set of outputs, labeled SDO, always carry the digital video data signal unless they are muted. If
the Reclocker is locked and not bypassed, these outputs carry a reclocked version of the input signal. If
the Reclocker is unlocked or bypassed, these outputs carry an unmodified replica of the input signal. The
outputs may be muted by the output mute control described in a later section.
The second set of outputs of the SD346EVK, labeled SCO/SDO2, can be set either to output a copy of
the data on the first set of outputs, either reclocked or not as described above, or to output the recovered
clock signal from the LMH0346SQ SDI Reclocker. The clock signal is only available when the
LMH0346SQ SDI reclocker is locked to a valid input signal.
The inputs and outputs of the SD346EVK PC board are AC-coupled with 4.7 µF 0603-size coupling
capacitors. These capacitors are rated for 6.3 VDC working voltage. The inputs and outputs of the
SD346EVK board may be terminated in any DC voltage that does not exceed this 6.3 V limit relative to
the negative power supply. The coupling capacitors may be replaced with 0603-size 0Ω resistors for DC-
coupled evaluation.
DC Power Connectors
DC power is applied to the SD346EVK by means of standard .175-inch diameter binding posts. Three
power supply terminals are provided. The first is a common ground, to which the negative supply voltage
should be connected. This is the black binding post on the board. The two red binding posts on the
board are meant to provide 3.3 VDC to 1) the LMH0346SQ SDI Reclocker alone, and 2) the remainder of
the circuitry on the SD346EVK board. The dual-supply configuration permits measurement of the current
drawn by the LMH0346SQ SDI Reclocker independent of the other devices on the board if desired. The
two supplies may be connected together if desired using either an external jumper or the onboard header
between the 3.3 V power supply terminals.
The power supply is not regulated on the SD346EVK board so the effects of power supply variations can
be evaluated. It is recommended that the maximum supply voltage rating of the LMH0346SQ (4 VDC)
not be exceeded.
Controls and Indicators
The control lines of the LMH0346SQ SDI Reclocker can be controlled by various means using the
SD346EVK. The primary method for controlling these lines is the DIP switches located on the
SD346EVK board. The DIP switches are labeled according to their function. When the switch actuator is
pushed to the right (seen from the top), the switch is closed. The schematic for the board indicates the
functions of each switch. The switch functionality is summarized in Table 1.
Two headers are also provided for operating the control lines of the LMH0346SQ SDI Reclocker. The
first is located immediately below the DIP switches. This header is meant to be used with two-pin
jumpers and provides parallel functionality to the DIP switches. When a jumper is installed on the header
it overrides the function of the equivalent DIP switch.
The second header is located to the right of the DIP switches. This header is meant to provide access for
remote control of the LMH0346SQ SDI Reclocker. When this header is used the DIP switches should all
be set in the open position and no jumpers should be installed on the control header. The connections for
this header are described in the schematic for the SD346EVK PC board. It is recommended that this
SD346EVK User Manual
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Rev 1.0
© 2008, National Semiconductor Corp.