SNVSC31A march   2023  – may 2023 LMR36501 , LMR36502

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD (Commercial) 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
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Enable, Shutdown, and Start-up
      2. 8.3.2  Adjustable Switching Frequency (with RT)
      3. 8.3.3  Power-Good Output Operation
      4. 8.3.4  Internal LDO, VCC UVLO, and VOUT/FB Input
      5. 8.3.5  Bootstrap Voltage and VBOOT-UVLO (BOOT Terminal)
      6. 8.3.6  Output Voltage Selection
      7. 8.3.7  Soft Start and Recovery from Dropout
        1. 8.3.7.1 Soft Start
        2. 8.3.7.2 Recovery from Dropout
      8. 8.3.8  Current Limit and Short Circuit
      9. 8.3.9  Thermal Shutdown
      10. 8.3.10 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 Operation
        5. 8.4.3.5 Dropout
  10. 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 VOUT / 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
        9. 9.2.2.9  External UVLO
        10. 9.2.2.10 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
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Device Nomenclature
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

9.2 Typical Application

Figure 9-1 shows a typical application circuit for the LMR36502. This device is designed to function over a wide range of external components and system parameters. However, the internal compensation is optimized for a certain range of external inductance and output capacitance. As a quick-start guide, Table 9-1 and Table 9-2 provide typical component values for a range of the most common output voltages.

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A. The RT pin is factory-set for externally adjustable switching frequency RT variants only. Tying this pin to GND results in 2.2-MHz or to VCC results in 1.1-MHz switching frequency. See Section 8.3.2 for details.
B. The MODE/SYNC pin is factory-set for fixed frequency frequency MODE/SYNC variants only. Tying this pin to GND results in AUTO mode.
Figure 9-1 Example Application Circuit
Table 9-1 Typical External Component Values for Adjustable Output LMR36502
FSW (1) (2) (kHz) VOUT (V) L (µH) NOMINAL COUT (RATED CAPACITANCE) MINIMUM COUT (RATED CAPACITANCE) RFBT (Ω) (3) RFBB (Ω) CIN CBOOT CVCC
400 3.3 33 1 × 47 µF 1 × 22 µF 33.2 k 14.3 k 2.2 µF + 1 × 100 nF 100 nF 1 µF
1000 3.3 15 2 × 22 µF 1 × 22 µF 33.2 k 14.3 k 2.2 µF + 1 × 100 nF 100 nF 1 µF
400 5 47 1 × 47 µF 1 × 22 µF 49.9 k 12.4 k 2.2 µF + 1 × 100 nF 100 nF 1 µF
1000 5 22 2 × 22 µF 1 × 22 µF 49.9 k 12.4 k 2.2 µF + 1 × 100 nF 100 nF 1 µF
(1) Inductor values are calculated based on typical VIN = 24 V.
(2) The switching frequencies listed here can be achieved in a number of ways depending on the device variant. For RT devices see Section 8.3.2. .
(3) For RFBT and RFBB values outside the range stated above, see Section 9.2.2.2.1.
Table 9-2 Typical External Component Values for Fixed Output LMR36502
FSW (1) (2) (kHz) VOUT (V) L (µH) NOMINAL COUT (RATED CAPACITANCE) MINIMUM COUT (RATED CAPACITANCE) RFBT (Ω) RFBB (Ω) (3) CIN CBOOT CVCC
400 3.3 68 1 × 47 µF 1 × 22 µF 0 DNP 2.2 µF + 1 × 100 nF 100 nF 1 µF
2200 3.3 10 1 × 10 µF 1 × 10 µF 0 DNP 2.2 µF + 1 × 100 nF 100 nF 1 µF
400 5 82 1 × 47 µF 1 × 22 µF 0 DNP 2.2 µF + 1 × 100 nF 100 nF 1 µF
2200 5 15 1 × 10 µF 1 × 10 µF 0 DNP 2.2 µF + 1 × 100 nF 100 nF 1 µF
(1) Inductor values are calculated based on typical VIN = 13.5 V.
(2) The switching frequencies listed here can be achieved in a number of ways depending on the device variant. For RT devices see Section 8.3.2.
(3) DNP = Do Not Populate.