LMH0394_15 Datasheet, PDF (22/35 Pages) Texas Instruments – 3G HD/SD SDI Low Power Extended Reach Adaptive Cable Equalizer

LMH0394
SNLS312M – AUGUST 2010 – REVISED JULY 2015
8 Application and Implementation
www.ti.com
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers must
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The LMH0394 3-Gbps HD/SD SDI Low Power Extended Reach 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, ST
259, and DVB-ASI standards. Additional features include separate carrier detect and output mute pins which may
be tied together to mute the output when no signal is present. A programmable mute reference is provided to
mute the output at a selectable level of signal degradation. The bypass pin allows the adaptive equalizer to be
bypassed. The LMH0394 accepts single-ended input. The input must be AC coupled. The LMH0394 correctly
handles equalizer pathological signals for standard definition and high definition serial digital video, as described
in ST RP 178 and RP 198, respectively.
8.1.1 Interfacing to 3.3-V SPI
The LMH0394 may be controlled through optional SPI register access. The LMH0394 SPI pins support 2.5-V
LVCMOS logic levels and are compliant with JEDEC JESD8-5 (see DC Electrical Characteristics). Care must be
taken when interfacing the SPI pins to other voltage levels.
The 2.5-V LMH0394 SPI pins may be interfaced to a 3.3-V compliant SPI host by using a voltage divider or level
translator. One implementation is a simple resistive voltage divider as shown in Figure 16.
3.16 k:
MOSI
3.3V
SCK
Compliant
SPI Host
3.16 k:
3.16 k:
SS
9.76 k:
9.76 k:
9.76 k:
MISO
Figure 16. 3.3-V SPI Interfacing
8.1.2 Crosstalk Immunity
Single-ended SDI signals are susceptible to crosstalk and good design practices must be employed to minimize
its effects. Most crosstalk originates through capacitive coupling from adjacent signals routed closely together
through traces and connectors. To reduce capacitive coupling, SDI signals must be appropriately spaced apart or
insulated from one another. This can be accomplished by physically isolating signal traces in the layout and by
providing additional ground pins between signal traces in connectors as necessary. These techniques help to
reduce crosstalk but do not eliminate it.
The LMH0394 was designed specifically with crosstalk in mind and incorporates advanced circuit design
techniques that help to isolate and minimize the effects of cross-coupling in high-density system designs. The
LMH0394’s enhanced design results in minimal degradation in cable reach in the presence of crosstalk and
overall superior immunity against cross-coupling from neighboring channels.
22
Submit Documentation Feedback
Product Folder Links: LMH0394
Copyright © 2010–2015, Texas Instruments Incorporated