LMH0384 Datasheet, PDF (10/29 Pages) National Semiconductor (TI) – 3 Gbps HD/SD SDI Extended Reach and Configurable Adaptive Cable Equalizer

LMH0384
SNLS308G – APRIL 2009 – REVISED JUNE 2015
7 Detailed Description
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7.1 Overview
The LMH0384 3-Gbps HD - SD SDI Extended Reach and Configurable Adaptive Cable Equalizer is designed to
equalize data transmitted over cable (or any media with similar dispersive loss characteristics). The equalizer
operates over a wide range of data rates from 125 Mbps to 2.97 Gbps and supports ST 424, ST 292, ST 344,
and ST 259 standards. The LMH0384 includes active sensing features and design enhancements including
longer cable equalization, lower output jitter, configurable pin mode and SPI modes, a power-saving sleep mode,
and programmable output common-mode voltage and swing. The LMH0384 implements DC restoration to
correctly handle pathological data conditions.
7.2 Functional Block Diagram
SDI
SDI
Equalizer
Filter
DC
Restoration/
Level Control
Output
Driver
BYPASS
SDO
SDO
SPI_EN
SPI Control
Energy
Detect
Energy
Detect
$
Automatic
Equalization
Control
Carrier
Detect
MUTE_REF
MUTE
CD
MUTE_REF
AEC+ AEC-
AUTO SLEEP
Figure 6. Pin Mode
7.3 Feature Description
7.3.1 Block Description
The Equalizer Filter block is a multistage adaptive filter. If BYPASS is high, the equalizer filter is disabled.
The DC Restoration / Level Control block receives the differential signals from the equalizer filter block. This
block incorporates a self-biasing DC restoration circuit to fully DC restore the signals. If BYPASS is high, this
function is disabled.
The signals before and after the DC Restoration / Level Control block are used to generate the Automatic
Equalization Control (AEC) signal. This control signal sets the gain and bandwidth of the equalizer filter. The
loop response in the AEC block is controlled by an external 1-µF capacitor placed across the AEC+ and AEC-
pins.
The Carrier Detect block generates the carrier detect signal based on the SDI input and an adjustment from the
Mute Reference block.
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