SLVSBM9E October   2013  – September 2018 LMZ31520

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     Efficiency
  3. 3 Description
    1.     Simplified Application
  4. 4 Specifications
    1. 4.1 Absolute Maximum Ratings
    2. 4.2 Recommended Operating Conditions
    3. 4.3 Thermal Information
    4. 4.4 Package Specifications
    5. 4.5 Electrical Characteristics
  5. 5 Device Information
    1.     Pin Functions
    2. 5.1 Functional Block Diagram
  6. 6 Typical Characteristics (PVIN = VIN = 12 V)
  7. 7 Typical Characteristics (PVIN = VIN = 5 V)
  8. 8 Application Information
    1. 8.1  Adjusting the Output Voltage
    2. 8.2  Frequency Select
    3. 8.3  Capacitor Recommendations for the LMZ31520 Power Supply
      1. 8.3.1 Capacitor Technologies
        1. 8.3.1.1 Electrolytic, Polymer-Electrolytic Capacitors
        2. 8.3.1.2 Ceramic Capacitors
        3. 8.3.1.3 Tantalum, Polymer-Tantalum Capacitors
        4. 8.3.1.4 Input Capacitor
        5. 8.3.1.5 Output Capacitor
    4. 8.4  Transient Response
    5. 8.5  Application Curves Device configured for FCCM mode of operation, (pin 3 connected to pin 19).
    6. 8.6  Application Schematics
    7. 8.7  Custom Design With WEBENCH® Tools
    8. 8.8  VIN and PVIN Input Voltage
    9. 8.9  3.3 V PVIN Operation
    10. 8.10 Power Good (PWRGD)
    11. 8.11 Slow Start (SS_SEL)
    12. 8.12 Auto-Skip Eco-mode / Forced Continuous Conduction Mode
    13. 8.13 Power-Up Characteristics
    14. 8.14 Pre-Biased Start-Up
    15. 8.15 Remote Sense
    16. 8.16 Output On/Off Inhibit (INH)
    17. 8.17 Overcurrent Protection
    18. 8.18 Current Limit (ILIM) Adjust
    19. 8.19 Thermal Shutdown
    20. 8.20 Layout Considerations
    21. 8.21 EMI
  9. 9 Revision History
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
        1. 10.1.1.1 Custom Design With WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Community Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  11. 11Mechanical, Packaging, and Orderable Information
    1. 11.1 Tape and Reel Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RLG|72
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.11 Slow Start (SS_SEL)

Connecting the SS_SEL pin to PWRGD or PGND sets the slow start interval of approximately 0.7 ms. The connection to either PWRGD or PGND determines the mode of the LMZ31520 as decribed in Auto-Skip Eco-mode / Forced Continuous Conduction Mode. Adding a resistor between SS_SEL pin and PWRGD or PGND increases the slow start time. Increasing the slow start time will reduce inrush current.Table 5 shows a resistor connected between SS_SEL pin and PWRGD to select FCCM and Figure 17 shows a resistor between SS_SEL pin and PGND to select Auto-skip mode. See Table 5 below for SS resistor values and timing interval.

LMZ31520 SSResistorFCCM.gifFigure 16. Slow-Start Resistor (RSS) in FCCM
LMZ31520 SSResistorAutoSkip.gifFigure 17. Slow-Start Resistor (RSS) in Auto-skip Mode

Table 5. Slow-Start Resistor Values and Slow-Start Time

RSS (kΩ) short 61.9 161 436
SS Time (msec) 0.7 1.4 2.8 5.6