SNVS953G December   2012  – May 2021 LM25018

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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 Characteristics
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 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  Control Overview
      2. 7.3.2  VCC Regulator
      3. 7.3.3  Regulation Comparator
      4. 7.3.4  Overvoltage Comparator
      5. 7.3.5  On-Time Generator
      6. 7.3.6  Current Limit
      7. 7.3.7  N-Channel Buck Switch and Driver
      8. 7.3.8  Synchronous Rectifier
      9. 7.3.9  Undervoltage Detector
      10. 7.3.10 Thermal Protection
      11. 7.3.11 Ripple Configuration
      12. 7.3.12 Soft Start
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Application Circuit: 12.5-V to 48-V Input and 10-V, 325-mA Output Buck Converter
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 8.2.1.2.2 RFB1, RFB2
          3. 8.2.1.2.3 Frequency Selection
          4. 8.2.1.2.4 Inductor Selection
          5. 8.2.1.2.5 Output Capacitor
          6. 8.2.1.2.6 Type III Ripple Circuit
          7. 8.2.1.2.7 VCC and Bootstrap Capacitor
          8. 8.2.1.2.8 Input Capacitor
          9. 8.2.1.2.9 UVLO Resistors
      2. 8.2.2 Application Curves
      3. 8.2.3 Typical Isolated DC-DC Converter Using LM25018
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
          1. 8.2.3.2.1  Transformer Turns Ratio
          2. 8.2.3.2.2  Total IOUT
          3. 8.2.3.2.3  RFB1, RFB2
          4. 8.2.3.2.4  Frequency Selection
          5. 8.2.3.2.5  Transformer Selection
          6. 8.2.3.2.6  Primary Output Capacitor
          7. 8.2.3.2.7  Secondary Output Capacitor
          8. 8.2.3.2.8  Type III Feedback Ripple Circuit
          9. 8.2.3.2.9  Secondary Diode
          10. 8.2.3.2.10 VCC and Bootstrap Capacitor
          11. 8.2.3.2.11 Input Capacitor
          12. 8.2.3.2.12 UVLO Resistors
          13. 8.2.3.2.13 VCC Diode
        3. 8.2.3.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

6.5 Electrical Characteristics

Typical values correspond to TJ = 25°C. Minimum and maximum limits apply over –40°C to 125°C junction temperature range, unless otherwise stated. VIN = 48 V unless otherwise stated. See(1).
PARAMETERTEST CONDITIONSMINTYPMAXUNIT
VCC SUPPLY
VCC RegVCC Regulator OutputVIN = 48 V, ICC = 20 mA6.257.68.55V
VCC Current LimitVIN = 48 V(2)26mA
VCC Undervoltage Lockout Voltage (VCC increasing)4.154.54.9V
VCC Undervoltage Hysteresis300mV
VCC Dropout VoltageVIN = 9 V, ICC = 20 mA2.3V
IIN Operating CurrentNonswitching, FB = 3 V1.75mA
IIN Shutdown CurrentUVLO = 0 V50225µA
SWITCH CHARACTERISTICS
Buck Switch RDS(ON)ITEST = 200 mA, BST-SW = 7 V0.81.8Ω
Synchronous RDS(ON)ITEST = 200 mA0.451Ω
Gate Drive UVLOVBST – VSW Rising2.433.6V
Gate Drive UVLO Hysteresis260mV
CURRENT LIMIT
Current Limit Threshold390575750mA
Current Limit Response TimeTime to Switch Off150ns
OFF-Time Generator (Test 1)FB = 0.1 V, VIN = 48 V12µs
OFF-Time Generator (Test 2)FB = 1.0 V, VIN = 48 V2.5µs
REGULATION AND OVERVOLTAGE COMPARATORS
FB Regulation LevelInternal Reference Trip Point for Switch ON1.21.2251.25V
FB Overvoltage ThresholdTrip Point for Switch OFF1.62V
FB Bias Current60nA
UNDERVOLTAGE SENSING FUNCTION
UV ThresholdUV Rising1.191.2251.26V
UV Hysteresis Input CurrentUV = 2.5 V–10–20–29µA
Remote Shutdown ThresholdVoltage at UVLO Falling0.320.66V
Remote Shutdown Hysteresis110mV
THERMAL SHUTDOWN
TsdThermal Shutdown Temperature165°C
Thermal Shutdown Hysteresis20°C
(1) All hot and cold limits are specified by correlating the electrical characteristics to process and temperature variations and applying statistical process control.
(2) VCC provides self bias for the internal gate drive and control circuits. Device thermal limitations limit external loading.