SNVSBS7A December   2021  – September 2022 LM5168 , LM5169

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  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
    6. 7.6 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  Control Architecture
      2. 8.3.2  Internal VCC Regulator and Bootstrap Capacitor
      3. 8.3.3  Internal Soft Start
      4. 8.3.4  On-Time Generator
      5. 8.3.5  Current Limit
      6. 8.3.6  N-Channel Buck Switch and Driver
      7. 8.3.7  Synchronous Rectifier
      8. 8.3.8  Enable, Undervoltage Lockout (EN/UVLO)
      9. 8.3.9  Power Good (PGOOD)
      10. 8.3.10 Thermal Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Active Mode
      3. 8.4.3 Sleep Mode
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Fly-Buck™ Converter Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1  Switching Frequency (RT)
        2. 9.2.2.2  Transformer Selection
        3. 9.2.2.3  Output Capacitor Selection
        4. 9.2.2.4  Secondary Output Diode
        5. 9.2.2.5  Setting Output Voltage
        6. 9.2.2.6  Input Capacitor
        7. 9.2.2.7  Type-3 Ripple Network
        8. 9.2.2.8  CBST Selection
        9. 9.2.2.9  Minimum Secondary Output Load
        10. 9.2.2.10 Example Design Summary
      3. 9.2.3 Application Curves
    3. 9.3 Typical Buck Application
      1. 9.3.1 Design Requirements
      2. 9.3.2 Detailed Design Procedure
        1. 9.3.2.1 Switching Frequency (RT)
        2. 9.3.2.2 Buck Inductor Selection
        3. 9.3.2.3 Setting the Output Voltage
        4. 9.3.2.4 Type-3 Ripple Network
        5. 9.3.2.5 Output Capacitor Selection
        6. 9.3.2.6 Input Capacitor Considerations
        7. 9.3.2.7 CBST Selection
        8. 9.3.2.8 Example Design Summary
      3. 9.3.3 Application Curves
    4. 9.4 Power Supply Recommendations
    5. 9.5 Layout
      1. 9.5.1 Thermal Considerations
      2. 9.5.2 Typical EMI Results
      3. 9.5.3 Layout Guidelines
        1. 9.5.3.1 Compact PCB Layout for EMI Reduction
        2. 9.5.3.2 Feedback Resistors
      4. 9.5.4 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

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

3 Description

The LM5169 and LM5168 synchronous buck converters are designed to regulate over a wide input voltage range, minimizing the need for external surge suppression components. A minimum controllable on time of 50 ns facilitates large step-down conversion ratios, enabling the direct step-down from a 48-V nominal input to low-voltage rails for reduced system complexity and solution cost. The LM516x operates during input voltage dips as low as 6 V, at nearly 100% duty cycle if needed, making it an excellent choice for wide input supply range industrial and high cell count battery pack applications.

With integrated high-side and low-side power MOSFETs, the LM5169 delivers up to 0.65-A of output current and the LM5168 delivers up to 0.3-A of output current. A constant on-time (COT) control architecture provides nearly constant switching frequency with excellent load and line transient response. The LM516x is available in FPWM or auto mode versions. FPWM mode provides forced CCM operation across the entire load range supporting isolated fly-buck converter applications. Auto mode enables ultra-low IQ and diode emulation mode operation for high light-load efficiency.

Device Information
PART NUMBER PACKAGE(1) BODY SIZE (NOM)
LM5169 SO PowerPAD (8) 4.89 mm × 3.90 mm
LM5168
(1) For all available packages, see the orderable addendum at the end of the data sheet.
GUID-43DA543F-FC83-488D-A322-AFDB7C343EEB-low.gifTypical Buck Application Circuit
GUID-2812ACA6-4747-4412-B794-895C7AB281EB-low.gifTypical Fly-Buck™ Converter Application Circuit