SNVSAS5 March   2018 LMR23615-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      Efficiency vs Load, VIN = 12 V
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  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
    6. 6.6 Timing Characteristics
    7. 6.7 Switching Characteristics
    8. 6.8 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  Fixed-Frequency Peak-Current-Mode Control
      2. 7.3.2  Adjustable Frequency
      3. 7.3.3  Adjustable Output Voltage
      4. 7.3.4  EN/SYNC
      5. 7.3.5  VCC, UVLO
      6. 7.3.6  Minimum ON-time, Minimum OFF-time and Frequency Foldback at Dropout Conditions
      7. 7.3.7  Internal Compensation and CFF
      8. 7.3.8  Bootstrap Voltage (BOOT)
      9. 7.3.9  Overcurrent and Short-Circuit Protection
      10. 7.3.10 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
      3. 7.4.3 CCM Mode
      4. 7.4.4 Light Load Operation
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Custom Design With WEBENCH® Tools
        2. 8.2.2.2  Output Voltage Setpoint
        3. 8.2.2.3  Switching Frequency
        4. 8.2.2.4  Inductor Selection
        5. 8.2.2.5  Output Capacitor Selection
        6. 8.2.2.6  Feed-Forward Capacitor
        7. 8.2.2.7  Input Capacitor Selection
        8. 8.2.2.8  Bootstrap Capacitor Selection
        9. 8.2.2.9  VCC Capacitor Selection
        10. 8.2.2.10 Undervoltage Lockout Setpoint
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Compact Layout for EMI Reduction
      2. 10.1.2 Ground Plane and Thermal Considerations
      3. 10.1.3 Feedback Resistors
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 Custom Design With WEBENCH® Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2 Typical Applications

The LMR23615-Q1 only requires a few external components to convert from a wide voltage range supply to a fixed output voltage. Figure 22 shows a basic schematic.

LMR23615-Q1 LMR2361DRR_typical_application_snvsav8.gifFigure 22. Application Circuit

The external components have to fulfill the needs of the application, but also the stability criteria of the device's control loop. Table 2 can be used to simplify the output filter component selection.

Table 2. L, COUT, and CFF Typical Values

fSW (kHz)VOUT (V)L (µH) (1)COUT (µF)(2)CFF (pF)(3)RFBT (kΩ)(4)(5)
200 3.3 22 200 220 51
5 33 150 120 88.7
12 56 68 See note(3) 243
24 56 33 See note(3) 510
400 3.3 10 120 100 51
5 15 90 68 88.7
12 33 47 See note(3) 243
24 33 22 See note (3) 510
1000 3.3 4.7 68 47 51
5 5.6 47 22 88.7
12 10 33 See note(3) 243
2200 3.3 2.2 33 22 51
5 3.3 22 15 88.7
(1) Inductance value is calculated based on VIN = 36 V.
(2) All the COUT values are after derating. Add more when using ceramic capacitors.
(3) High ESR COUT will give enough phase boost and CFF not needed.
(4) RFBT = 0 Ω for VOUT = 1 V. RFBB = 22.1 kΩ for all other VOUT setting.
(5) For designs with RFBT other than recommended value, adjust CFF such that (CFF × RFBT) is unchanged and adjust RFBB such that (RFBT / RFBB) is unchanged.