This document gives the MADI (Multichannel Audio Digital Interface) specification requirements and necessary changes to enable LMH12xx device family to achieve compatibility with this specifications.
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The MADI Specification standard describes the 125-Mbps NRZI, 4/5-bit coded serial data frame format and electrical characteristics for a multichannel audio digital interface. This specification governs requirements for serial digital transmission over coax or fiber-optic lines of 28, 56, or 64 channels represented at a common sampling frequency of 32 KHz to 96 KHz with a resolution of up to 24-bits per channel. Only a single-point interface from one transmitter to a receiver is supported. This document describes electrical parameters and changes necessary to make the LMH12xx device family compatible with these requirements.
Same as SDI (Serial Digital Interface), the transmission media can either be over a 75-Ω coax cable or a fiber-optic cable. The following sections list the MADI specification electrical parameter requirements:
Output impedance should be 75-Ω ±2 Ω.
MADI data pattern is DC-balanced and thus the average voltage of the terminated output should be 0 V ±0.1 V
After a 75-Ω termination, the output voltage should be within 0.3 to 0.6 V.
After a 75-Ω termination, the 20/80% rise/fall time should be within 1 nS and 3 nS