SNVS566J April   2008  – June 2017 LM5118

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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 UVLO
      2. 7.3.2 Oscillator and Sync Capability
      3. 7.3.3 Error Amplifier and PWM Comparator
      4. 7.3.4 Ramp Generator
      5. 7.3.5 Current Limit
      6. 7.3.6 Maximum Duty Cycle
      7. 7.3.7 Soft Start
      8. 7.3.8 HO Output
      9. 7.3.9 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Buck Mode Operation: VIN > VOUT
      2. 7.4.2 Buck-Boost Mode Operation: VIN ≊ VOUT
      3. 7.4.3 High Voltage Start-Up Regulator
      4. 7.4.4 Enable
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      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  R7 = RT
        3. 8.2.2.3  Inductor Selection, L1
        4. 8.2.2.4  R13 = RSENSE
        5. 8.2.2.5  C15 = CRAMP
        6. 8.2.2.6  Inductor Current Limit Calculation
        7. 8.2.2.7  C9 - C12 = Output Capacitors
        8. 8.2.2.8  D1
        9. 8.2.2.9  D4
        10. 8.2.2.10 C1 - C5 = Input Capacitor
        11. 8.2.2.11 C20
        12. 8.2.2.12 C8
        13. 8.2.2.13 C16 = CSS
        14. 8.2.2.14 R8, R9
        15. 8.2.2.15 R1, R3, C21
        16. 8.2.2.16 R2
        17. 8.2.2.17 Snubber
        18. 8.2.2.18 Error Amplifier Configuration
          1. 8.2.2.18.1 R4, C18, C17
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Thermal Considerations
    2. 9.2 Bias Power Dissipation Reduction
  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 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • Ultra-Wide Input Voltage Range From 3 V to 75 V
  • Emulated Peak Current Mode Control
  • Smooth Transition Between Step-Down and Step-Up Modes
  • Switching Frequency Programmable to 500 KHz
  • Oscillator Synchronization Capability
  • Internal High Voltage Bias Regulator
  • Integrated High and Low-Side Gate Drivers
  • Programmable Soft-Start Time
  • Ultra-Low Shutdown Current
  • Enable Input Wide Bandwidth Error Amplifier
  • 1.5% Feedback Reference Accuracy
  • Thermal Shutdown
  • Package: 20-Pin HTSSOP (Exposed Pad)
  • Create a Custom Design Using the LM5118 With the WEBENCH® Power Designer

2 Applications

    Industrial Buck-Boost Supplies

3 Description

The LM5118 wide voltage range Buck-Boost switching regulator controller features all of the functions necessary to implement a high-performance, cost-efficient Buck-Boost regulator using a minimum of external components. The Buck-Boost topology maintains output voltage regulation when the input voltage is either less than or greater than the output voltage, making it especially suitable for automotive applications. The LM5118 operates as a buck regulator while the input voltage is sufficiently greater than the regulated output voltage and gradually transitions to the buck-boost mode as the input voltage approaches the output. This dual-mode approach maintains regulation over a wide range of input voltages with optimal conversion efficiency in the buck mode and a glitch-free output during mode transitions. This easy-to-use controller includes drivers for the high-side buck MOSFET and the low-side boost MOSFET. The regulators control method is based upon current mode control using an emulated current ramp. Emulated current mode control reduces noise sensitivity of the pulse-width modulation circuit, allowing reliable control of the very small duty cycles necessary in high input voltage applications. Additional protection features include current limit, thermal shutdown and an enable input. The device is available in a power-enhanced, 20-pin HTSSOP package featuring an exposed die attach pad to aid thermal dissipation.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM5118 HTSSOP (20) 6.50 mm × 4.40 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Simplified Schematic

LM5118 30058501.gif

Efficiency vs VIN and IOUT, VOUT = 12 V

LM5118 30058503.gif