LMH0302 Datasheet, PDF (8/18 Pages) Texas Instruments – 3-Gbps HD/SD SDI Cable Driver

LMH0302
SNLS247H – APRIL 2007 – REVISED JUNE 2016
8 Application and Implementation
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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 should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The LMH0302 is a single-channel SDI cable driver that supports different application spaces. The following
sections describe the typical use cases and common implementation practices.
8.1.1 General Guidance for All Applications
The SMPTE specifications define the use of AC-coupling capacitors for transporting uncompressed serial data
streams with heavy low-frequency content. This specification requires the use of a 4.7-µF AC-coupling capacitor
to avoid low frequency DC wander. The 75-Ω signal is also required to meet certain rise and fall timing to
facilitate highest eye opening for the receiving device.
SMPTE specifies the requirements for the Serial Digital Interface to transport digital video at SD, HD, 3 Gbps,
and higher data rates over coaxial cables. One of the requirements is meeting the required return loss. This
requirement specifies how closely the port resembles 75-Ω impedance across a specified frequency band.
Output return loss is dependent on board design. The LMH0302 supports these requirements.
8.2 Typical Application
V_CC
SD/HD
75:
75:
0.1 PF
Differential
Input
1.0 PF
ENABLE
49.9:
1.0 PF
49.9:
0.1 PF
ENABLE
SDI _SD/HD
SDO
LMH0302
SDO
SDI ^RREF
V_CC
6.8 nH
75:
75:
4.7 PF
4.7 PF
6.8 nH
750:
Copyright © 2016, Texas Instruments Incorporated
Figure 3. Application Circuit
8
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