LMH0046MH Datasheet, PDF (8/20 Pages) Texas Instruments – LMH0046 HD/SD SDI Reclocker With Dual Differential Outputs

LMH0046
SNLS222F – APRIL 2006 – REVISED APRIL 2013
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DEVICE DESCRIPTION
The LMH0046 HD/SD SDI Reclocker is used in many types of digital video signal processing equipment.
Supported serial digital video standards are SMPTE 259M (A & C) and SMPTE 292M. Corresponding serial data
rates are 143 Mbps, 270 Mbps, 1.483 Gbps and 1.485 Gbps. DVB-ASI data at 270 Mbps may also be retimed.
The LMH0046 retimes the serial data stream to suppress accumulated 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 data-rate clock or second serial data output select, manual rate select
input, SD/HD rate output, lock detect output, auto/manual data bypass and output mute.
Serial data inputs are CML and LVPECL compatible. Serial data and data-rate 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 800 mV_P-P ±10% into 100Ω AC or DC-coupled differential loads.
Logic inputs and outputs are LVCMOS compatible.
The device package is a 20-pin HTSSOP with an exposed die attach pad. The exposed die attach pad is
electrically connected to device ground (V_EE) and is the negative electrical terminal for the device. This terminal
must be connected to the negative power supply or circuit ground.
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 Table 2. The serial
data input is differential LVPECL compatible. The input is intended to be DC interfaced to devices such as the
LMH0034 adaptive cable equalizer. The input is not internally terminated or biased. The input may be AC-
coupled if a suitable input bias voltage is provided. Figure 4 shows the equivalent input circuit for SDI and SDI.
The LMH0046 has two, retimed, differential, serial data outputs, SDO and SCO/SDO2. These outputs provide
low jitter, differential, retimed data to devices such as the LMH0002 cable driver or the LMH0031 deserializer.
Output SCO/SDO2 is multiplexed and can provide either a second serial data output or a serial data-rate clock
output. Figure 5 shows the equivalent output circuit for SDO, SDI, 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 data-rate 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 MUTE input is a logic low level.
SCO/SDO2 also mutes when the Bypass mode is activated when this output is operating as the serial clock
output. 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
terminated networks.
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