SNVS520F August   2008  – November 2016 LM3686

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (Continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics: Linear Regulator - LILO
    6. 7.6 Electrical Characteristics: Linear Regulator - LDO
    7. 7.7 Electrical Characteristics: DC-DC Converter
    8. 7.8 Electrical Characteristics: Global Parameters (DCDC, LILO, and LDO)
    9. 7.9 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 DC-DC Converter Operation
        1. 8.3.1.1 PWM Operation
        2. 8.3.1.2 PFM Operation
        3. 8.3.1.3 Internal Synchronous Rectification
        4. 8.3.1.4 Current Limiting
        5. 8.3.1.5 Soft Start
      2. 8.3.2 Linear Regulator Operation (LILO)
        1. 8.3.2.1 Start-up Mode
      3. 8.3.3 Current Limiting (LDO and LILO)
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Application Selection
        2. 9.2.2.2 Inductor Selection
          1. 9.2.2.2.1 Method 1
          2. 9.2.2.2.2 Method 2
        3. 9.2.2.3 External Capacitors
        4. 9.2.2.4 Input Capacitor Selection
          1. 9.2.2.4.1 CIN_DC-DC
          2. 9.2.2.4.2 CIN_LILO
          3. 9.2.2.4.3 CIN_LDO
        5. 9.2.2.5 Output Capacitor
          1. 9.2.2.5.1 COUT_DCDC
          2. 9.2.2.5.2 COUT_LILO
          3. 9.2.2.5.3 COUT_LDO
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 DSBGA Package Assembly and Use
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

5 Description (Continued)

Three enable (EN_x) pins allow the separate operation of either the DC-DC, post-regulation linear regulator, or the linear regulator alone. If the DC-DC is not enabled during start-up of the post-regulation linear regulator, a parallel small-pass transistor supplies the linear regulator from VBATT with maximal 50 mA. In the combined operation where both enables are raised together, the small-pass transistor is deactivated and the big pass transistor provides 350 mA output current. In shutdown mode (EN_x pins pulled low), the device turns off and reduces battery consumption to 2.5 μA (typical).

The LM3686 is available in a 12-pin DSBGA package. A high-switching frequency of 3 MHz (typical) allows the use of a few tiny surface-mount components. Only six external surface-mount components, an inductor and five ceramic capacitors, are required to establish a 15.66 mm2 total solution size.