SNVSCF0 October   2024 LM65680-Q1

ADVANCE INFORMATION  

  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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Descriptions
      1. 7.3.1  Output Voltage Selection
      2. 7.3.2  EN Pin and Use as VIN UVLO
      3. 7.3.3  Device Configuration
      4. 7.3.4  Single-Output Dual-Phase Operation
      5. 7.3.5  Mode Selection
        1. 7.3.5.1 MODE/SYNC Pin Uses for Synchronization
        2. 7.3.5.2 Clock Locking
      6. 7.3.6  Adjustable Switching Frequency
      7. 7.3.7  Dual Random Spread Spectrum (DRSS)
      8. 7.3.8  Internal LDO, VCC UVLO, and BIAS Input
      9. 7.3.9  Bootstrap Voltage (BST Pin)
      10. 7.3.10 Soft Start and Recovery From Dropout
      11. 7.3.11 Safety Features
        1. 7.3.11.1 Power-Good Monitor
        2. 7.3.11.2 Overcurrent and Short-Circuit Protection
        3. 7.3.11.3 Hiccup
        4. 7.3.11.4 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
        1. 7.4.2.1 Peak Current Mode Operation
        2. 7.4.2.2 Auto Mode Operation
          1. 7.4.2.2.1 Diode Emulation
        3. 7.4.2.3 FPWM Mode Operation
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Power Train Components
        1. 8.1.1.1 Buck Inductor
        2. 8.1.1.2 Output Capacitors
        3. 8.1.1.3 Input Capacitors
        4. 8.1.1.4 EMI Filter
      2. 8.1.2 Error Amplifier and Compensation
      3. 8.1.3 Maximum Ambient Temperature
        1. 8.1.3.1 Derating Curves
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Inductor Selection
        2. 8.2.2.2 Output Capacitors
        3. 8.2.2.3 Feed-forward Capacitor (CFF)
        4. 8.2.2.4 Input Capacitor Selection
        5. 8.2.2.5 Choosing the Switching Frequency
        6. 8.2.2.6 Setting the Output Voltage
        7. 8.2.2.7 Compensation Components
        8. 8.2.2.8 CBST
        9. 8.2.2.9 External UVLO
      3. 8.2.3 Application Curves
    3. 8.3 Best Design Practices
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
        1. 8.5.1.1 Ground and Thermal Considerations
      2. 8.5.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Development Support
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
        1. 9.2.1.1 PCB Layout Resources
        2. 9.2.1.2 Thermal Design Resources
    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
    1. 11.1 Tape and Reel Information

Package Options

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

8.2.3 Application Curves

Unless otherwise specified the following conditions apply: VIN = 48V, TA = 25°C.

VOUT = 5V FSW = 400kHz FPWM
Figure 8-9 Efficiency vs IOUT, Linear Scale
VOUT = 5V FSW = 400kHz PFM
Figure 8-11 Efficiency vs IOUT, Linear Scale
VIN = 48V
VOUT = 5V		 IOUT = 8A
FSW = 400kHz		 FPWM
Figure 8-13 Full Load Switching
VIN stepped to 48V
VOUT = 5V		 IOUT = 8A (resistive)
FSW = 400kHz		 FPWM
Figure 8-15 VIN Start-Up Characteristic
VIN = 48V
VOUT = 5V		 FPWM
Figure 8-17 Load Transient, 0A to 8A
VIN = 48V
VOUT = 5V		 FSW = 400kHz
IOUT = 8A (resistive)		 FPWM
DRSS = ON
Figure 8-19 Typical CISPR 25 Conducted EMI 150kHz - 108MHz Green: Average Detect,
Purple = Peak Detect

VIN = 48V
VOUT = 5V
IOUT = 8A (resistive)
Fc = 72.46kHz		 FPWM
L = 3.3μH
FSW = 400kHz
PM = 51.29°

Figure 8-21 Bode Plot
VOUT = 5V FSW = 400kHz FPWM
Figure 8-10 Efficiency vs IOUT, Log Scale
VOUT = 5V FSW = 400kHz PFM
Figure 8-12 Efficiency vs IOUT, Log Scale
VIN = 48V
VOUT = 5V		 No load PFM
Figure 8-14 PFM Switching
VIN = 48V
VOUT = 5V		 IOUT = 8A (resistive)
FSW = 400kHz		 FPWM
Figure 8-16 EN Start-Up and Shutdown Characteristic
VIN = 48V
VOUT = 5V		 IOUT = 8A (resistive)
FSW = 400kHz		 FPWM
Figure 8-18 Short-Circuit Recovery
VIN = 48V
VOUT = 5V		 FSW = 400kHz
IOUT = 8A (resistive)		 FPWM
Figure 8-20 Thermal Performance, TAMB = 25°C, No Airflow