The LMH1983 is a highly-integrated programmable audio/video (A/V) clock generator intended for broadcast and professional applications. It can replace multiple PLLs and VCXOs used in applications supporting SMPTE serial digital video (SDI) and digital audio AES3/EBU standards. It offers low-jitter reference clocks for any SDI transmitter to meet stringent output jitter specifications without additional clock cleaning circuits.

The LMH1983 features automatic input format detection, simple programming of multiple A/V output formats, genlock or digital free-run modes, and override programmability of various automatic functions. The recognized input formats include HVF syncs for the major video standards, 27 MHz, 10 MHz, and 32/44.1/48/96 kHz audio word clocks.

The dual-stage PLL architecture integrates four PLLs with three on-chip VCOs. The first stage (PLL1) uses an external low-noise 27 MHz VCXO with narrow loop bandwidth to provide a clean reference clock for the next stage. The second stage (PLL2, 3, 4) consists of three parallel VCO PLLs for simultaneous generation of the major digital A/V clock fundamental rates, including 148.5 MHz, 148.5/1.001 MHz, and 98.304 MHz (4 × 24.576 MHz). Each PLL can generate a clock and a timing pulse to indicate top of frame (TOF).Read more