Texas Instruments LMK61E07 Ultra-Low Jitter Oscillators

Texas Instruments LMK61E07 Ultra-Low Jitter Programmable Oscillator with Internal EEPROM is a functional solution to generate commonly used reference clocks. The device provides a fractional-N frequency synthesizer with integrated VCOs, resulting in ultra-low noise with high performance. The flexible output can be configured with options of LVPECL, LVDS, or HCSL. A factory-programmed default output frequency is triggered via the self-start-up feature from the on-chip EEPROM. Another option offered for the output frequency consists of the device registering and EEPROM settings being fully programmable in-system through an I2C serial interface. The Texas Instruments LMK61E07, by way of the I2C serial interface, provides fine and coarse frequency margining control, creating a digitally-controlled oscillator (DCXO).

Other features include a 3.3V operating voltage and an industrial temperature range of –40ºC to +85ºC, all encompassed in a 7mm x 5mm 8-Pin package. Compatibility with xDSL requirements is achieved with the PLL feedback divider, which updates to adjust the output frequency without spikes or glitches in steps of <5.2ppb using a PFD of 100MHz (R divider=1, doubler enabled) for compatibility with broadcast video requirements. The frequency margining features also facilitate system design verification tests (DVT), such as standards compliance and system timing margin testing.

Features

  • Ultra-low noise, high performance
    • Jitter: 90fs RMS typical fOUT >100MHz on LMK61E07
    • PSRR: –70dBc, robust supply noise immunity on LMK61E07
  • Flexible output format on LMK61E07
    • LVPECL up to 1GHz
    • LVDS up to 900MHz
    • HCSL up to 400MHz
  • Total frequency tolerance of ±25ppm
  • 70.656MHz default frequency
  • System level features
    • Glitch-less frequency margining up to ±1000ppm from nominal
    • Internal EEPROM with user-configurable start-up settings
  • Other features
    • Fast mode I2C up to 1000kHz device control 
    • 3.3V operating voltage
    • Industrial temperature range (–40ºC to +85ºC)
    • 7mm × 5mm 8-pin package

Applications

  • High-performance replacement for crystal, SAW, or silicon-based oscillators
  • Switches, routers, network line cards, Base Band Units (BBU), servers, storage/SAN
  • Test and measurement
  • Medical imaging
  • FPGA, processor attach
  • xDSL, broadcast video

Functional Block Diagram

Block Diagram - Texas Instruments LMK61E07 Ultra-Low Jitter Oscillators
Published: 2018-05-03 | Updated: 2022-11-08