SNVSA03E October   2014  – October 2018 LM5160 , LM5160A

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Synchronous Buck Application Circuit
      2.      Typical Fly-Buck Application Circuit
  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 Switching Characteristics
    7. 6.7 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  Control Circuit
      2. 7.3.2  VCC Regulator
      3. 7.3.3  Regulation Comparator
      4. 7.3.4  Soft Start
      5. 7.3.5  Error Amplifier
      6. 7.3.6  On-Time Generator
      7. 7.3.7  Current Limit
      8. 7.3.8  N-Channel Buck Switch and Driver
      9. 7.3.9  Synchronous Rectifier
      10. 7.3.10 Enable / Undervoltage Lockout (EN/UVLO)
      11. 7.3.11 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Forced Pulse Width Modulation (FPWM) Mode
      2. 7.4.2 Undervoltage Detector
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Ripple Configuration
    2. 8.2 Typical Applications
      1. 8.2.1 LM5160 Synchronous Buck (10-V to 60-V Input, 5-V Output, 1.5-A Load)
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Custom Design With WEBENCH® Tools
          2. 8.2.1.2.2  Feedback Resistor Divider - RFB1, RFB2
          3. 8.2.1.2.3  Switching Frequency - RON
          4. 8.2.1.2.4  Inductor - L
          5. 8.2.1.2.5  Output Capacitor - COUT
          6. 8.2.1.2.6  Series Ripple Resistor - RESR
          7. 8.2.1.2.7  VCC and Bootstrap Capacitors - CVCC, CBST
          8. 8.2.1.2.8  Input Capacitor - CIN
          9. 8.2.1.2.9  Soft-Start Capacitor - CSS
          10. 8.2.1.2.10 EN/UVLO Resistors - RUV1, RUV2
        3. 8.2.1.3 Application Curves
      2. 8.2.2 LM5160 Isolated Fly-Buck (18-V to 32-V Input, 12-V, 4.5-W Isolated Output)
        1. 8.2.2.1 LM5160 Fly-Buck Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Selection of VOUT1 and Turns Ratio
          2. 8.2.2.2.2 Secondary Rectifier Diode
          3. 8.2.2.2.3 External Ripple Circuit
          4. 8.2.2.2.4 Output Capacitor - COUT2
        3. 8.2.2.3 Application Curves
      3. 8.2.3 LM5160A Isolated Fly-Buck (18-V to 32-V Input, 12-V, 4.5-W Isolated Output)
    3. 8.3 Do's and Don'ts
  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 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 Receiving Notification of Documentation Updates
    5. 11.5 Community Resources
    6. 11.6 Trademarks
    7. 11.7 Electrostatic Discharge Caution
    8. 11.8 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.1.2.2 Feedback Resistor Divider - RFB1, RFB2

With the required output voltage setpoint at 5 V and VFB = 2 V (typical), calculate the ratio of R6 (RFB1) to R5 (RFB2) using Equation 9.

Equation 9. LM5160 LM5160A eq06_snvsa03.gif

The resistor ratio calculates to be 3:2. Choose standard values of R6 (RFB1) = 2 kΩ and R5 (RFB2 ) = 3.01 kΩ. Higher or lower values can be used as long as a ratio of the 3:2 is maintained.