SNVSBY5B december   2020  – may 2023 LMR43610 , LMR43620

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 System Characteristics
    7. 7.7 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  Enable, Start-Up, and Shutdown
      2. 8.3.2  External CLK SYNC (with MODE/SYNC)
        1. 8.3.2.1 Pulse-Dependent MODE/SYNC Pin Control
      3. 8.3.3  Adjustable Switching Frequency (with RT)
      4. 8.3.4  Power-Good Output Operation
      5. 8.3.5  Internal LDO, VCC, and VOUT/FB Input
      6. 8.3.6  Bootstrap Voltage and VBOOT-UVLO (BOOT Terminal)
      7. 8.3.7  Output Voltage Selection
      8. 8.3.8  Soft Start and Recovery from Dropout
        1. 8.3.8.1 Recovery from Dropout
      9. 8.3.9  Current Limit and Short Circuit
      10. 8.3.10 Thermal Shutdown
      11. 8.3.11 Input Supply Current
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Standby Mode
      3. 8.4.3 Active Mode
        1. 8.4.3.1 CCM Mode
        2. 8.4.3.2 Auto Mode – Light-Load Operation
          1. 8.4.3.2.1 Diode Emulation
          2. 8.4.3.2.2 Frequency Reduction
        3. 8.4.3.3 FPWM Mode – Light-Load Operation
        4. 8.4.3.4 Minimum On-Time (High Input Voltage) Operation
        5. 8.4.3.5 Dropout
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Choosing the Switching Frequency
        2. 9.2.2.2 Setting the Output Voltage
          1. 9.2.2.2.1 FB for Adjustable Output
        3. 9.2.2.3 Inductor Selection
        4. 9.2.2.4 Output Capacitor Selection
        5. 9.2.2.5 Input Capacitor Selection
        6. 9.2.2.6 CBOOT
        7. 9.2.2.7 VCC
        8. 9.2.2.8 CFF Selection
          1. 9.2.2.8.1 External UVLO
        9. 9.2.2.9 Maximum Ambient Temperature
      3. 9.2.3 Application Curves
    3. 9.3 Best Design Practices
    4. 9.4 Power Supply Recommendations
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
        1. 9.5.1.1 Ground and Thermal Considerations
      2. 9.5.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
      2. 10.1.2 Device Nomenclature
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
9.2.2.2.1 FB for Adjustable Output

If other voltages are desired, the VOUT/FB pin can be connected to a feedback resistor divider network to set the output voltage. The divider network is comprised of RFBT and RFBB, and closes the loop between the output voltage and the converter. The converter regulates the output voltage by holding the voltage on the FB pin equal to the internal reference voltage, VREF. The converter determines whether fixed output voltage or adjustable output voltage is required by sensing the resistance of the feedback path during start-up. To ensure that the converter regulates to the desired output voltage, the typical minimum value for the parallel combination of RFBT and RFBB is 5 kΩ while the typical maximum value is 10 kΩ as shown in Equation 5. Equation 6 can be used as a starting point to determine the value of RFBT. Reference Table 9-6 for a list of acceptable resistor values for various output voltages.

Equation 5. 5 kΩ < RFBT||RFBB ≤10 kΩ
Equation 6. RFBT≤10 kΩ× VOUT1 V
Table 9-6 Recommended Feedback Resistor Values for Various Output Voltages
VOUT (V) RFBT (1) (kΩ) RFBB (kΩ)
2.5 24.9 16.5
3.3 33.2 14.3
5 49.9 12.4
6 60.4 12.1
9 90.9 11.3
(1) RFBT and RFBB based on 1% standard resistor values.

For this 5-V example, the user can choose the LMR43620MB5RPER and connect the VOUT/FB pin directly to the output capacitor.