SNVSB87 November   2018 LM3880-Q1

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Simple Power Supply Sequencing
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
      1. 6.5.1 Timing Requirements
    6. 6.6 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Enable Pin Operation
      2. 7.3.2 Incomplete Sequence Operation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Power Up With EN Pin
      2. 7.4.2 Power Down With EN Pin
  8. Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Open Drain Flags Pullup
      2. 8.1.2 Enable the Device
    2. 8.2 Typical Application
      1. 8.2.1 Simple Sequencing of Three Power Supplies
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Sequencing Using Independent Flag Supply
    3. 8.3 Do's and Don'ts
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Device Nomenclature
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

Do's and Don'ts

Connecting the EN pin to VCC is not recommended. During power up, the EN voltage should be kept below the EN threshold until VCC rises above the minimum operating voltage. This will be violated if EN is connected to VCC, and undefined operation at the flag outputs can occur, especially during slow VCC rising slew rates. For systems requiring only power-up sequencing, a capacitor at the EN pin can be used to create a delay or a resistor divider can be used to enable the device based on a certain voltage threshold. While these solutions will work for power-up, it will not power-down the flag outputs in sequential fashion since the flag outputs will simply follow the input supply. For systems requiring both power-up and power-down sequencing, an external enable signal should be used, such as a GPIO signal from a microcontroller, to properly control power-up and power-down of the flag outputs.

LM3880-Q1 lm3880-dos-donts.pngFigure 19. Recommended EN Connection