AEC+

Equalizer

Filter

AEC-

MUTE

DC

Restoration/

Level Control

Automatic

Equalization

Control

SDI

SDI

SDO0

SDO0

BYPASS

Output

Drivers

$

Energy

Detect

Energy

Detect

CD

AUTO SLEEP

Carrier

Detect

SPI_EN

SPI Control

De-Emphasis

Control

SDO1

SDO1

SDO1_

DISABLE

LMH0395

www.ti.com

SNLS323M – AUGUST 2010 – REVISED JULY 2015

7 Detailed Description

7.1 Overview

The LMH0395 is a 3-Gbps HD/SD SDI low power extended reach adaptive cable equalizer. It 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, ST

259, and DVB-ASI standards. The LMH0395 provides extended cable reach with improved immunity to crosstalk

and ultra-low power consumption. The LMH0395 equalizer features 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 LMH0395

implements DC restoration to correctly handle pathological data conditions.

The LMH0395 includes power management to further reduce power consumption when no input signal is

present. The output driver offers programmable de-emphasis for up to 40” of FR4 trace losses.

7.2 Functional Block Diagram

The LMH0395 supports two modes of operation. In pin mode, the LMH0395 operates with control pins to set its

operating state. In SPI mode, an optional SPI serial interface can be used to access and configure multiple

LMH0395 devices in a daisy-chain configuration.

This allows users to program the output common-mode voltage and swing, output de-emphasis level, input

launch amplitude, and power management settings. Users may also access a cable length indicator and all pin

mode features.

7.3 Feature Description

The Equalizer Filter block is a multi-stage 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 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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