SNVSB91C July   2019  – June 2020 LMR36506-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      Efficiency versus Output Current VOUT = 3.3 V (Fixed), 2.2 MHz
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD (Automotive) Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Characteristics
    7. 7.7 Switching Characteristics
    8. 7.8 System Characteristics
    9. 7.9 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 UVLO, and VOUT/BIAS Input
      6. 8.3.6  Bootstrap Voltage and VCBOOT-UVLO (CBOOT Terminal)
      7. 8.3.7  Output Voltage Selection
      8. 8.3.8  Spread Spectrum
      9. 8.3.9  Soft Start and Recovery from Dropout
        1. 8.3.9.1 Recovery from Dropout
      10. 8.3.10 Current Limit and Short Circuit
      11. 8.3.11 Thermal Shutdown
      12. 8.3.12 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 What to Do and What Not to Do
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Ground and Thermal Considerations
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.1 Enable, Start-up and Shutdown

Voltage at the EN pin controls the start-up or remote shutdown of the LMR36506-Q1 family of devices. The part stays shut down as long as the EN pin voltage is less than VEN-WAKE = 0.4 V. During the shutdown, the input current drawn by the device typically drops down to 0.5 µA (VIN = 13.5 V). With the voltage at the EN pin greater than the VEN-WAKE, the device enters the device standby mode, the internal LDO powers up to generate VCC. As the EN voltage increases further, approaching VEN-VOUT, the device finally starts to switch, entering the start-up mode, with a soft start. During the device shutdown process, when the EN input voltage measures less than (VEN-VOUT – VEN-HYST), the regulator stops switching and re-enters the device standby mode. Any further decrease in the EN pin voltage, below VEN-WAKE, the device is then firmly shut down. The high-voltage compliant EN input pin can be connected directly to the VIN input pin if remote precision control is not needed. The EN input pin must not be allowed to float. The various EN threshold parameters and their values are listed in the Electrical Characteristics. Figure 8 shows the precision enable behavior, Figure 9 depicting a typical remote EN start-up waveform in an application. Once EN goes high, after a delay of about 1 ms, the output voltage begins to rise with a soft start and reaches close to the final value in about 2.67 ms (tss). After a delay of about 2 ms (tPGOOD_ACT), the PGOOD flag goes high. During start-up, the device is not allowed to enter FPWM mode until the soft-start time has elapsed. This time is measured from the rising edge of EN. Check External UVLO section for component selection.

LMR36506-Q1 FEATuvlFIG.gifFigure 7. VIN UVLO Using the EN pin
LMR36506-Q1 en_threshold_graph_revA.gifFigure 8. Precision Enable Behavior
LMR36506-Q1 EN_Startup.gifFigure 9. Enable Start-up
VIN = 12 V, VOUT = 5 V, IOUT = 600 mA