LMH0303 Datasheet, PDF (8/27 Pages) National Semiconductor (TI) – 3 Gbps HD/SD SDI Cable Driver with Cable Detect

LMH0303
SNLS285H – APRIL 2008 – REVISED MAY 2016
7 Detailed Description
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7.1 Overview
The LMH0303 ST 424, ST292, ST259 serial digital cable driver is a monolithic, high-speed cable driver designed
for use in serial digital video data transmission applications. The LMH0303 drives 75-Ω transmission lines
(Belden 8281, 1694A, Canare L-5CFB, or equivalent) at data rates up to 2.97 Gbps.
The LMH0303 provides two selectable slew rates for ST 259 and ST 292/424 compliance. The output voltage
swing is adjustable through a single external resistor ( R_REF) or SMBus interface in 5-mV steps.
The LMH0303 cable detect feature senses near-end termination to determine if a cable is attached to the output
BNC. The LMH0303 input loss of signal (LOS) detects the presence of a valid signal at the 100-Ω differential
input of the cable driver. These features can be used to activate power-save mode. These features are
accessible through an SMBus interface.
The LMH0303 is powered from a single 3.3 V supply. Power consumption is typically 130 mW in SD mode and
155 mW in HD mode. The LMH0303 is available in a 16-pin WQFN package.
7.2 Functional Block Diagram
LOS
SDI
+
SDI
-
Fault
Detect
SDO
SDO
+
-
RREF
Bias Generator
Control
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7.3 Feature Description
The LMH0303 data path consists of several key blocks as shown in the Functional Block Diagram. These key
circuits are:
• Loss-of-signal detector
• Input interfacing
• Output interfacing
• Output slew rate control
• Cable fault detection
• SMBus configuration
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