SNVSAV8B June   2017  – August 2020 LMR23615

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  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  Enable/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  Feedforward 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 Support 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 only requires a few external components to convert from a wide voltage range supply to a fixed output voltage. Figure 8-1 shows a basic schematic.

GUID-0BD68106-A34F-4462-B60D-29A25B63C547-low.gifFigure 8-1 Application Circuit

The external components must fulfill the needs of the application, but also the stability criteria of the device control loop. Table 8-1 can be used to simplify the output filter component selection.

Table 8-1 L, COUT, and CFF Typical Values
fSW (kHz)VOUT (V)L (µH) (1)COUT (µF) (2)CFF (pF)(4)RFBT (kΩ)(3)
2003.32220022051
53315012088.7
125668See note(5)243
245633See note(5)510
4003.31012010051
515906888.7
123347See note(5)243
243322See note(5)510
10003.34.7684751
55.6472288.7
121033See note(5)243
22003.32.2332251
53.3221588.7
(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) RFBT = 0 Ω for VOUT = 1 V. RFBB = 22.1 kΩ for all other VOUT settings.
(4) For designs with RFBT other than recommended value, adjust CFF so that (CFF × RFBT) is unchanged and adjust RFBB such that (RFBT / RFBB) is unchanged.
(5) High ESR COUT gives enough phase boost and CFF not needed.