SNVSB35B May   2018  – June 2020 LM26420-Q1

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

Package Options

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

5 Pin Configuration and Functions

RUM Package
16-Pin WQFN
Top View
LM26420-Q1 30069601.gif
PWP Package
20-Pin HTSSOP
Top View
LM26420-Q1 30069602.gif

Pin Functions: 16-Pin WQFN

PIN TYPE DESCRIPTION
NUMBER NAME
1,2 VIND1 P Power input supply for Buck 1
3 SW1 P Output switch for Buck 1. Connect to the inductor.
4 PGND1 G Power ground pin for Buck 1
5 FB1 A Feedback pin for Buck 1. Connect to external resistor divider to set output voltage.
6 PG1 G Power Good Indicator for Buck 1. Pin is connected through a resistor to an external supply (open-drain output).
7 PG2 G Power Good Indicator for Buck 2. Pin is connected through a resistor to an external supply (open-drain output).
8 FB2 A Feedback pin for Buck 2. Connect to external resistor divider to set output voltage.
9 PGND2 G Power ground pin for Buck 2
10 SW2 P Output switch for Buck 2. Connect to the inductor.
11, 12 VIND2 A Power Input supply for Buck 2
13 EN2 A Enable control input. Logic high enable operation for Buck 2. Do not allow this pin to float or be greater than VIN + 0.3 V.
14 AGND G Signal ground pin. Place the bottom resistor of the feedback network as close as possible to pin.
15 VINC A Input supply for control circuitry
16 EN1 A Enable control input. Logic high enable operation for Buck 1. Do not allow this pin to float or be greater than VIN + 0.3 V.
DAP Die Attach Pad — Connect to system ground for low thermal impedance and as a primary electrical GND connection.

Pin Functions 20-Pin HTSSOP

PIN TYPE DESCRIPTION
NUMBER NAME
1 VINC A Input supply for control circuitry
2 EN1 A Enable control input. Logic high enable operation for Buck 1. Do not allow this pin to float or be greater than VIN + 0.3 V.
3, 4 VIND1 A Power Input supply for Buck 1
5 SW1 P Output switch for Buck 1. Connect to the inductor.
6,7 PGND1 G Power ground pin for Buck 1
8 FB1 A Feedback pin for Buck 1. Connect to external resistor divider to set output voltage.
9 PG1 G Power Good Indicator for Buck 1. Pin is connected through a resistor to an external supply (open-drain output).
10, 11, DAP Die Attach Pad — Connect to system ground for low thermal impedance, but it cannot be used as a primary GND connection.
12 PG2 G Power Good Indicator for Buck 2. Pin is connected through a resistor to an external supply (open-drain output).
13 FB2 A Feedback pin for Buck 2. Connect to external resistor divider to set output voltage.
14, 15 PGND2 G Power ground pin for Buck 2
16 SW2 P Output switch for Buck 2. Connect to the inductor.
17, 18 VIND2 A Power Input supply for Buck 2
19 EN2 A Enable control input. Logic high enable operation for Buck 2. Do not allow this pin to float or be greater than VIN + 0.3 V.
20 AGND G Signal ground pin. Place the bottom resistor of the feedback network as close as possible to pin.