1 Features

1• Two Simultaneous LVDS Output Clocks with

Selectable Frequencies and Hi-Z Capability:

– SD Clock: 27 MHz or 67.5 MHz

– HD Clock: 74.25 MHz, 74.25/1.001 MHz,

148.5 MHz or 148.5/1.001 MHz

• Low-Jitter Output Clocks May Be Directly

Connected to an FPGA Serializer to Meet SMPTE

SDI Jitter Specifications

• Top of Frame (TOF) Pulse with Programmable

Output Format Timing and Hi-Z Capability

• Two reference ports (A and B) With H and V Sync

Inputs

• Supports Cross-Locking of Input and Output

Timing

• External Loop Filter Allows Control of Loop

Bandwidth, Jitter Transfer, and Lock Time

Characteristics

• Free Run or Holdover Operation on Loss of

Reference

• User-Defined Free Run Control Voltage Input

• I2C Interface and Control Registers

• 3.3-V and 2.5-V Supplies

2 Applications

• Video Genlock and Synchronization

• FPGA SDI SerDes Recovered Clock Generation

• Triple Rate 3G/HD/SD-SDI SerDes

• Video Capture, Conversion, Editing and

Distribution

• Video Displays and Projectors

• Broadcast and Professional Video Equipment

3 Description

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 field-

programmable 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).