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LMK05028 Low-Jitter Dual-Channel Network Synchronizer Clock With EEPROM
SNAS724B
February 2018 – February 2025
LMK05028
PRODUCTION DATA
CONTENTS
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LMK05028 Low-Jitter Dual-Channel Network Synchronizer Clock With EEPROM
1
1
Features
2
Applications
3
Description
4
Pin Configuration and Functions
4.1
Device Start-Up Modes
5
Specifications
5.1
Absolute Maximum Ratings
5.2
ESD Ratings
5.3
Recommended Operating Conditions
5.4
Thermal Information
5.5
Electrical Characteristics
5.6
Timing Diagrams
5.7
Typical Characteristics
6
Parameter Measurement Information
6.1
Output Clock Test Configurations
7
Detailed Description
7.1
Overview
7.1.1
ITU-T G.8262 (SyncE) Standards Compliance
7.2
Functional Block Diagrams
7.2.1
PLL Architecture Overview
7.2.2
3-Loop Mode
7.2.2.1
PLL Output Clock Phase Noise Analysis in 3-Loop Mode
7.2.3
2-Loop REF-DPLL Mode
7.2.4
2-Loop TCXO-DPLL Mode
7.2.5
PLL Configurations for Common Applications
7.3
Feature Description
7.3.1
Oscillator Input (XO_P/N)
7.3.2
TCXO/OCXO Input (TCXO_IN)
7.3.3
Reference Inputs (INx_P/N)
7.3.4
Clock Input Interfacing and Termination
7.3.5
Reference Input Mux Selection
7.3.5.1
Automatic Input Selection
7.3.5.2
Manual Input Selection
7.3.6
Hitless Switching
7.3.7
Gapped Clock Support on Reference Inputs
7.3.8
Input Clock and PLL Monitoring, Status, and Interrupts
7.3.8.1
XO Input Monitoring
7.3.8.2
TCXO Input Monitoring
7.3.8.3
Reference Input Monitoring
7.3.8.3.1
Reference Validation Timer
7.3.8.3.2
Amplitude Monitor
7.3.8.3.3
Missing Pulse Monitor (Late Detect)
7.3.8.3.4
Runt Pulse Monitor (Early Detect)
7.3.8.3.5
Frequency Monitoring
7.3.8.4
PLL Lock Detectors
7.3.8.5
Tuning Word History
7.3.8.6
Status Outputs
7.3.8.7
Interrupt
7.3.9
PLL Channels
7.3.9.1
PLL Frequency Relationships
7.3.9.2
Analog PLL (APLL)
7.3.9.3
APLL XO Doubler
7.3.9.4
APLL Phase Frequency Detector (PFD) and Charge Pump
7.3.9.5
APLL Loop Filter
7.3.9.6
APLL Voltage Controlled Oscillator (VCO)
7.3.9.6.1
VCO Calibration
7.3.9.7
APLL VCO Post-Dividers (P1, P2)
7.3.9.8
APLL Fractional N Divider (N) With SDM
7.3.9.9
REF-DPLL Reference Divider (R)
7.3.9.10
TCXO/OCXO Input Doubler and M Divider
7.3.9.11
TCXO Mux
7.3.9.12
REF-DPLL and TCXO-DPLL Time-to-Digital Converter (TDC)
7.3.9.13
REF-DPLL and TCXO-DPLL Loop Filter
7.3.9.14
REF-DPLL and TCXO-DPLL Feedback Dividers
7.3.10
Output Clock Distribution
7.3.11
Output Channel Muxes
7.3.11.1
TCXO/Ref Bypass Mux
7.3.12
Output Dividers
7.3.13
Clock Outputs (OUTx_P/N)
7.3.13.1
AC-Differential Output (AC-DIFF)
7.3.13.2
HCSL Output
7.3.13.3
LVCMOS Output (1.8 V, 2.5 V)
7.3.13.4
Output Auto-Mute During LOL or LOS
7.3.14
Glitchless Output Clock Start-Up
7.3.15
Clock Output Interfacing and Termination
7.3.16
Output Synchronization (SYNC)
7.3.17
Zero-Delay Mode (ZDM) Configuration
7.3.18
PLL Cascading With Internal VCO Loopback
7.4
Device Functional Modes
7.4.1
Device Start-Up Modes
7.4.1.1
EEPROM Mode
7.4.1.2
ROM Mode
7.4.2
PLL Operating Modes
7.4.2.1
Free-Run Mode
7.4.2.2
Lock Acquisition
7.4.2.3
Locked Mode
7.4.2.4
Holdover Mode
7.4.3
PLL Start-Up Sequence
7.4.4
Digitally-Controlled Oscillator (DCO) Mode
7.4.4.1
DCO Frequency Step Size
7.4.4.2
DCO Direct-Write Mode
7.4.5
Zero-Delay Mode (ZDM)
7.4.6
Cascaded PLL Operation
7.5
Programming
7.5.1
Interface and Control
7.5.2
I2C Serial Interface
7.5.2.1
I2C Block Register Transfers
7.5.3
SPI Serial Interface
7.5.3.1
SPI Block Register Transfer
7.5.4
Register Map Generation
7.5.5
General Register Programming Sequence
7.5.6
EEPROM Programming Flow
7.5.6.1
EEPROM Programming Using Register Commit (Method #1)
7.5.6.1.1
Write SRAM Using Register Commit
7.5.6.1.2
Program EEPROM
7.5.6.2
EEPROM Programming Using Direct SRAM Writes (Method #2)
7.5.6.2.1
Write SRAM Using Direct Writes
7.5.7
Read SRAM
7.5.8
Read EEPROM
7.5.9
EEPROM Start-Up Mode Default Configuration
7.6
Register Maps
8
Application and Implementation
8.1
Application Information
8.1.1
Device Start-Up Sequence
8.1.2
Power Down (PDN) Pin
8.1.3
Power Rail Sequencing, Power Supply Ramp Rate, and Mixing Supply Domains
8.1.3.1
Mixing Supplies
8.1.3.2
Power-On Reset (POR) Circuit
8.1.3.3
Powering Up From a Single-Supply Rail
8.1.3.4
Power Up From Split-Supply Rails
8.1.3.5
Non-Monotonic or Slow Power-Up Supply Ramp
8.1.4
Slow or Delayed XO Start-Up
8.2
Typical Application
8.2.1
Design Requirements
8.2.2
Detailed Design Procedure
8.2.3
Application Curves
8.3
Do's and Don'ts
8.4
Power Supply Recommendations
8.4.1
Power Supply Bypassing
8.5
Layout
8.5.1
Layout Guidelines
8.5.2
Layout Example
8.5.3
Thermal Reliability
9
Device and Documentation Support
9.1
Device Support
9.1.1
Clock Architect
9.1.2
TICS Pro
9.2
Documentation Support
9.2.1
Related Documentation
9.3
Receiving Notification of Documentation Updates
9.4
Support Resources
9.5
Trademarks
9.6
Electrostatic Discharge Caution
9.7
Glossary
10
Revision History
11
Mechanical, Packaging, and Orderable Information
IMPORTANT NOTICE
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Data Sheet
LMK05028
Low-Jitter Dual-Channel Network Synchronizer Clock With EEPROM
1
Features
Two Independent PLL Channels Featuring:
Jitter: 150fs RMS for Outputs ≥ 100MHz
Phase Noise: –112dBc/Hz at 100Hz Offset for 122.88MHz
Hitless Switching: 50ps Phase Transient With Phase Cancellation
Programmable Loop Bandwidth With Fastlock
Standards-Compliant Synchronization and Holdover Using a Low-Cost TCXO/OCXO
Any Input to Any Output Frequency Translation
Four Reference Clock Inputs
Priority-Based Input Selection
Digital Holdover on Loss of Reference
Eight Clock Outputs With Programmable Drivers
Up to Six Different Output Frequencies
AC-LVDS, AC-CML, AC-LVPECL, HCSL, and 1.8V or 2.5V LVCMOS Output Formats
EEPROM/ROM for Custom Clocks on Power-Up
Flexible Configuration Options
Up to 750MHz on Input and Output
XO: 10MHz to 100MHz, TCXO: 10MHz to 54MHz
DCO Mode: < 1ppt/Step for Fine Frequency and Phase Steering (IEEE 1588 Slave)
Zero Delay for Deterministic Phase Offset
Robust Clock Monitoring and Status
I
2
C or SPI Interface
Excellent Power Supply Noise Rejection (PSNR)
3.3V Supply With 1.8V, 2.5V, or 3.3V Outputs
Industrial Temperature Range: –40°C to +85°C
2
Applications
SyncE (G.8262), SONET/SDH (Stratum 3/3E, G.813, GR-1244, GR-253), IEEE 1588 PTP Slave Clock, or Optical Transport Network (G.709)
Wired networking
Inter/Intra DC interconnect
Timing card, line card
Data center and enterprise computing
Broadband fixed line access
Industrial
Test and measurement
Medical imaging
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