SNVSBS7B December   2021  – December 2024 LM5168 , LM5169

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Control Architecture
      2. 7.3.2  Internal VCC Regulator and Bootstrap Capacitor
      3. 7.3.3  Internal Soft Start
      4. 7.3.4  On-Time Generator
      5. 7.3.5  Current Limit
      6. 7.3.6  N-Channel Buck Switch and Driver
      7. 7.3.7  Synchronous Rectifier
      8. 7.3.8  Enable, Undervoltage Lockout (EN/UVLO)
      9. 7.3.9  Power Good (PGOOD)
      10. 7.3.10 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
      3. 7.4.3 Sleep Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Fly-Buck™ Converter Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Switching Frequency (RT)
        2. 8.2.2.2  Transformer Selection
        3. 8.2.2.3  Output Capacitor Selection
        4. 8.2.2.4  Secondary Output Diode
        5. 8.2.2.5  Setting Output Voltage
        6. 8.2.2.6  Input Capacitor
        7. 8.2.2.7  Type-3 Ripple Network
        8. 8.2.2.8  CBST Selection
        9. 8.2.2.9  Minimum Secondary Output Load
        10. 8.2.2.10 Example Design Summary
      3. 8.2.3 Application Curves
    3. 8.3 Typical Buck Application
      1. 8.3.1 Design Requirements
      2. 8.3.2 Detailed Design Procedure
        1. 8.3.2.1 Switching Frequency (RT)
        2. 8.3.2.2 Buck Inductor Selection
        3. 8.3.2.3 Setting the Output Voltage
        4. 8.3.2.4 Type-3 Ripple Network
        5. 8.3.2.5 Output Capacitor Selection
        6. 8.3.2.6 Input Capacitor Considerations
        7. 8.3.2.7 CBST Selection
        8. 8.3.2.8 Example Design Summary
      3. 8.3.3 Application Curves
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Thermal Considerations
      2. 8.5.2 Typical EMI Results
      3. 8.5.3 Layout Guidelines
        1. 8.5.3.1 Compact PCB Layout for EMI Reduction
        2. 8.5.3.2 Feedback Resistors
      4. 8.5.4 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

5 Pin Configuration and Functions

LM5168 LM5169 8-Pin SO PowerPAD™Integrated Circuit Package(Top View) Figure 5-1 8-Pin SO PowerPAD™Integrated Circuit Package(Top View)
LM5168 LM5169 8-Pin WSON NGU Package (Top View) Figure 5-2 8-Pin WSON NGU Package (Top View)
Table 5-1 Pin Functions
PIN TYPE(1) DESCRIPTION
NO. NAME
1 GND G Ground connection for internal circuits
2 VIN P/I Regulator supply input pin to the high-side power MOSFET and internal bias regulator. Connect directly to the input supply of the buck converter with short, low impedance paths.
3 EN/UVLO I Precision enable and undervoltage lockout (UVLO) programming pin. If the EN/UVLO rising voltage is below 1.1 V, the converter is in shutdown mode with all functions disabled. If the UVLO voltage is greater than 1.1 V and below 1.5 V, the converter is in standby mode with the internal VCC regulator operational and no switching. If the EN/UVLO voltage is above 1.5 V, the start-up sequence begins.
4 RT I On-time programming pin. A resistor between this pin and GND sets the buck switch on time.
5 FB I Feedback input of voltage regulation comparator
6 PGOOD O Power-good indicator. This pin is an open-drain output pin. Connect to a source voltage through an external pullup resistor between 10 kΩ to 100 kΩ. Connect to GND if the PGOOD feature is not needed.
7 BST P/I Bootstrap gate-drive supply. Required to connect a high-quality 2.2-nF X7R ceramic capacitor between BST and SW to bias the internal high-side gate driver.
8 SW P Switching node that is internally connected to the source of the high-side NMOS buck switch and the drain of the low-side NMOS synchronous rectifier. Connect to the switching node of the power inductor.
— EP — Exposed pad of the package. No internal electrical connection. Solder the EP to the GND pin and connect to a large copper plane to reduce thermal resistance.
(1) G = Ground, I = Input, O = Output, P = Power