SNVSA85C October   2015  – January 2017 LM27761

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 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
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Undervoltage Lockout
      2. 7.3.2 Input Current Limit
      3. 7.3.3 PFM Operation
      4. 7.3.4 Output Discharge
      5. 7.3.5 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Enable Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application - Regulated Voltage Inverter
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Charge-Pump Voltage Inverter
        3. 8.2.2.3 Negative Low-Dropout Linear Regulator
        4. 8.2.2.4 Power Dissipation
        5. 8.2.2.5 Output Voltage Setting
        6. 8.2.2.6 External Capacitor Selection
          1. 8.2.2.6.1 Charge-Pump Output Capacitor
          2. 8.2.2.6.2 Input Capacitor
          3. 8.2.2.6.3 Flying Capacitor
          4. 8.2.2.6.4 LDO Output Capacitor
      3. 8.2.3 Application Curves
  9. 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 Development Support
        1. 11.1.1.1 Custom Design With WEBENCH® Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

8.2.2.6.1 Charge-Pump Output Capacitor

In typical applications, a 4.7-µF low-ESR ceramic charge-pump output capacitor (C3) is recommended. Different output capacitance values can be used to reduce charge pump ripple, shrink the solution size, and/or cut the cost of the solution. However, changing the output capacitor may also require changing the flying capacitor or input capacitor to maintain good overall circuit performance.

In higher-current applications, a 10-µF, 10-V low-ESR ceramic output capacitor is recommended. If a small output capacitor is used, the output ripple can become large during the transition between PFM mode and constant switching. To prevent toggling, a 2-µF capacitance is recommended. For example, 10-µF, 10-V output capacitor in a 0402 case size typically has only 2-µF capacitance when biased to 5 V.