SNVSB35B May   2018  – June 2020

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      LM26420 Dual Buck DC/DC Converter
      2.      LM26420 Efficiency (Up to 93%)
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions: 16-Pin WQFN
    2.     Pin Functions 20-Pin HTSSOP
  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 Per Buck
    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 Soft Start
      2. 7.3.2 Power Good
      3. 7.3.3 Precision Enable
    4. 7.4 Device Functional Modes
      1. 7.4.1 Output Overvoltage Protection
      2. 7.4.2 Undervoltage Lockout
      3. 7.4.3 Current Limit
      4. 7.4.4 Thermal Shutdown
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Programming Output Voltage
      2. 8.1.2 VINC Filtering Components
      3. 8.1.3 Using Precision Enable and Power Good
      4. 8.1.4 Overcurrent Protection
    2. 8.2 Typical Applications
      1. 8.2.1 2.2-MHz, 0.8-V Typical High-Efficiency Application Circuit
        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 Inductor Selection
          3. 8.2.1.2.3 Input Capacitor Selection
          4. 8.2.1.2.4 Output Capacitor
          5. 8.2.1.2.5 Calculating Efficiency and Junction Temperature
        3. 8.2.1.3 Application Curves
      2. 8.2.2 2.2-MHz, 1.8-V Typical High-Efficiency Application Circuit
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
      3. 8.2.3 LM26420-Q12.2-MHz, 2.5-V Typical High-Efficiency Application Circuit
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
        3. 8.2.3.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
      1. 10.3.1 Method 1: Silicon Junction Temperature Determination
      2. 10.3.2 Thermal Shutdown Temperature Determination
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

6.5 Electrical Characteristics Per Buck

Over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VFB Feedback Voltage 0.788 0.8 0.812 V
ΔVFB/VIN Feedback Voltage Line Regulation VIN = 3 V to 5.5 V 0.05 %/V
IB Feedback Input Bias Current 0.4 100 nA
UVLO Undervoltage Lockout VIN Rising 2.628 2.9 V
VIN Falling 2 2.3 V
UVLO Hysteresis 330 mV
FSW Switching Frequency 2.01 2.2 2.65 MHz
FFB Frequency Foldback 300 kHz
DMAX Maximum Duty Cycle 86% 91.5%
RDSON_TOP TOP Switch On Resistance WQFN-16 Package 75 135 mΩ
HTSSOP-20 Package 70 135
RDSON_BOT BOTTOM Switch On Resistance WQFN-16 Package 55 100 mΩ
TSSOP-20 Package 45 80
ICL_TOP TOP Switch Current Limit VIN = 3.3 V 2.4 3.3 A
ICL_BOT BOTTOM Switch Reverse Current Limit VIN = 3.3 V 0.4 0.75 A
ΔΦ Phase Shift Between SW1 and SW2 160 180 200 °
VEN_TH Enable Threshold Voltage 0.97 1.04 1.12 V
Enable Threshold Hysteresis 0.15
ISW_TOP Switch Leakage –0.7 µA
IEN Enable Pin Current Sink/Source 5 nA
VPG-TH-U Upper Power Good Threshold FB Pin Voltage Rising 848 925 1,008 mV
Upper Power Good Hysteresis 40 mV
VPG-TH-L Lower Power Good Threshold FB Pin Voltage Rising 656 710 791 mV
Lower Power Good Hysteresis 40 mV
IQVINC VINC Quiescent Current (non-switching) with both outputs on VFB = 0.9 V 3.3 5 mA
VINC Quiescent Current (switching) with both outputs on VFB = 0.7 V 4.7 6.2
VINC Quiescent Current (shutdown) VEN = 0 V 0.05 µA
IQVIND VIND Quiescent Current (non-switching) VFB = 0.9 V 0.9 1.5 mA
VIND Quiescent Current (switching) VFB = 0.7 V 11 15
IQVIND VIND Quiescent Current (switching) LM26420Q0 VFB = 0.7 V 11 18 mA
IQVIND VIND Quiescent Current (shutdown) VEN = 0 V 0.1 µA
TSD Thermal Shutdown Temperature 165 °C