SD346EVK National Semiconductor, SD346EVK Datasheet - Page 8

• 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: -

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Device Description
The LMH0346 3 Gbps HD/SD SDI Reclocker is used in many
types of digital video signal processing equipment. Supported
serial digital video standards are SMPTE 259M (C), SMPTE
292M, and SMPTE 424M. Corresponding serial data rates
are 270 Mbps, 1.483 Gbps, 1.485 Gbps, 2.967 Gbps, and
2.97 Gbps. DVB-ASI data at 270 Mbps may also be retimed.
The LMH0346 retimes the serial data stream to suppress ac-
cumulated jitter. It provides two low-jitter, differential, serial
data outputs. The second output may be selected to output
either serial data or a low-jitter serial data-rate clock. Controls
and indicators are: serial clock or second serial data output
select, manual rate select input, SD/HD rate output, lock de-
tect output, auto/manual data bypass and output mute.
Serial data inputs are CML and LVPECL compatible. Serial
data and clock outputs are differential CML and produce
LVPECL compatible levels. The output buffer design can
drive AC or DC-coupled, terminated 100Ω differential loads.
The differential output level is 750 mV
coupled differential loads. Logic inputs and outputs are
LVCMOS compatible.
The device package is a 20-pin e-TSSOP or a 24-pin LLP.
Both package options have an exposed die attach pad. The
exposed die attach pad is electrically connected to device
ground (V
device. This terminal must be connected to the negative pow-
er supply or circuit ground.
EE
) and is the negative electrical terminal for the
P-P
FIGURE 1. Equivalent SDI Input Circuit (SDI, SDI)
into 100Ω AC or DC-
8
Serial Data Inputs, Serial Data and
Clock Outputs
SERIAL DATA INPUT AND OUTPUTS
The differential serial data input, SDI, accepts serial digital
video data at the rates specified in
input is differential LVPECL compatible. The input is intended
to be DC interfaced to devices such as the LMH0344 adaptive
cable equalizer. The input is not internally terminated or bi-
ased. The input may be AC-coupled if a suitable input bias
voltage is provided.
for SDI and SDI.
The LMH0346 has two, retimed, differential, serial data out-
puts, SDO and SCO/SDO2. These outputs provide low jitter,
differential, retimed data to devices such as the LMH0302
cable driver. Output SCO/SDO2 is multiplexed and can pro-
vide either a second serial data output or a serial clock output.
Figure 2
SCO/SDO2, and SCO/SDO2.
The SCO_EN input controls the operating mode for the SCO/
SDO2 output. When the SCO_EN input is high the SCO/
SDO2 output provides a serial clock. When SCO_EN is low,
the SCO/SDO2 output provides retimed serial data.
Both differential serial data outputs, SDO and SCO/SDO2,
are muted when the OUTPUT MUTE input is a logic low level.
SCO/SDO2 also mutes when the Bypass mode is activated
and this output is operating as the serial clock output
(SCO_EN input is high). When muted, SDO and SDO (or
SDO2 and SDO2) will assume opposite differential output
levels. The CML serial data outputs are differential LVPECL
compatible. These outputs have internal 50Ω pull-ups and are
suitable for driving AC or DC-coupled, 100Ω center-tapped,
AC grounded or 100Ω un-center-tapped, differentially termi-
nated networks.
shows the equivalent output circuit for SDO, SDO,
Figure 1
shows the equivalent input circuit
20215008
Table
1. The serial data