MULTI-RATE VIDEO CLOCK GENERAT
The LMH1982 device is a multi-rate video clock generator ideal for use in a wide range of 3-Gbps (3G), high-definition (HD), and standard-definition (SD) video applications, such as video synchronization, serial digital interface (SDI) serializer and deserializer (SerDes), video conversion, video editing, and other broadcast and professional video systems. The LMH1982 can generate two simultaneous SD and HD clocks and a Top of Frame (TOF) pulse. In genlock mode, the device's phase locked loops (PLLs) can synchronize the output signals to H sync and V sync input signals applied to either of the reference ports. The input reference can have analog timing from Texas Instrument's LMH1981 multi-format video sync separator or digital timing from an SDI deserializer and should conform to the major SD and HD standards. When a loss of reference occurs, the device can default to free run operation where the output timing accuracy will be determined by the external bias on the free run control voltage input. The LMH1982 can replace discrete PLLs and fieldprogrammable gate array (FPGA) PLLs with multiple voltage controlled crystal oscillators (VCXOs). Only one 27.0000 MHz VCXO and loop filter are externally required for genlock mode. The external loop filter as well as programmable PLL parameters can provide narrow loop bandwidths to minimize jitter transfer. HD clock output jitter as low as 40 ps peak-to-peak can help designers using FPGA SerDes meet stringent SDI output jitter specifications. The LMH1982 is offered in a space-saving 5 mm x 5 mm 32-pin WQFN package and provides low total power consumption of about 250 mW (typical).