SNAS642A June   2014  – July 2014 LMK00804B

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified Schematic
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Pin Characteristics
    2. 7.2  Absolute Maximum Ratings
    3. 7.3  Handling Ratings
    4. 7.4  Recommended Operating Conditions
    5. 7.5  Thermal Information
    6. 7.6  Power Supply Characteristics
    7. 7.7  LVCMOS / LVTTL DC Characteristics
    8. 7.8  Differential Input DC Characteristics
    9. 7.9  Electrical Characteristics (VDDO = 3.3 V ± 5%)
    10. 7.10 Electrical Characteristics (VDDO = 2.5 V ± 5%)
    11. 7.11 Electrical Characteristics (VDDO = 1.8 V ± 0.15 V)
    12. 7.12 Electrical Characteristics (VDDO = 1.5 V ± 5%)
    13. 7.13 Typical Characteristics
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
      1. 9.2.1 25
    3. 9.3 Feature Description
      1. 9.3.1 Clock Enable Timing
    4. 9.4 Device Functional Modes
      1. 9.4.1 Clock Input Function
  10. 10Applications and Implementation
    1. 10.1 Application Information
    2. 10.2 Output Clock Interface Circuit
    3. 10.3 Input Detail
    4. 10.4 Input Clock Interface Circuits
    5. 10.5 Typical Applications
      1. 10.5.1 Design Requirements
      2. 10.5.2 Detailed Design Procedure
      3. 10.5.3 Application Curves
        1. 10.5.3.1 System-Level Phase Noise and Additive Jitter Measurement
    6. 10.6 Do's and Don'ts
      1. 10.6.1 Power Considerations
      2. 10.6.2 Recommendations for Unused Input and Output Pins
      3. 10.6.3 Input Slew Rate Considerations
  11. 11Power Supply Recommendations
    1. 11.1 Power Supply Considerations
      1. 11.1.1 Power-Supply Filtering
      2. 11.1.2 Thermal Management
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 Ground Planes
      2. 12.1.2 Power Supply Pins
      3. 12.1.3 Differential Input Termination
      4. 12.1.4 LVCMOS Input Termination
      5. 12.1.5 Output Termination
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
    2. 13.2 Trademarks
    3. 13.3 Electrostatic Discharge Caution
    4. 13.4 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9 Detailed Description

9.1 Overview

The LMK00804B is a low skew, high performance clock fanout buffer which can distribute up to four LVCMOS/LVTTL outputs (3.3-V, 2.5-V, 1.8-V, or 1.5-V levels) from one of two selectable inputs, which can accept differential or single-ended inputs. The clock enable input is synchronized internally to eliminate runt or glitch pulses on the outputs when the clock enable terminal is asserted or de-asserted. The outputs are held in logic low state when the clock is disabled. A separate output enable terminal controls whether the outputs are active state or high-impedance state. The low additive jitter and phase noise floor, and guaranteed output and part-to-part skew characteristics make the LMK00804B ideal for applications demanding high performance and repeatability.

9.2 Functional Block Diagram

9.2.1

0001.gif

9.3 Feature Description

9.3.1 Clock Enable Timing

After CLK_EN switches, the clock outputs are disabled or enabled following a rising and falling input clock edge as shown in Figure 8. In the enabled mode, the output states are a function of the CLK/nCLK or LVCMOS_CLK inputs as described in Clock Input Function.
0011.gifFigure 8. Clock Enable Timing Diagram

9.4 Device Functional Modes

The device can provide fan-out and level translation from differential or single-ended input to LVCMOS/LVTTL output, where the output VOH and VOL levels are determined by the VDDO output supply voltage and output load condition. Refer to the Clock Input Function.

9.4.1 Clock Input Function

Table 1.

INPUTS OUTPUTS INPUT to OUTPUT MODE POLARITY
CLK (or LVCMOS_CLK) nCLK Qx
0 1 LOW Differential (or Single-Ended) to Single-Ended Non-inverting
1 0 HIGH Differential (or Single-Ended) to Single-Ended Non-inverting
0 Floating or Biased LOW Single-Ended to Single-Ended Non-inverting
1 Floating or Biased HIGH Single-Ended to Single-Ended Non-inverting
Biased 0 HIGH Single-Ended to Single-Ended Inverting
Biased 1 LOW Single-Ended to Single-Ended Inverting