SNVS252H September   2003  – November 2018 LM5007

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Schematic
  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 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 Hysteretic Control Circuit Overview
      2. 7.3.2 High-Voltage Bias Supply Regulator
      3. 7.3.3 Overvoltage Comparator
      4. 7.3.4 On-Time Generator and Shutdown
      5. 7.3.5 Overcurrent Protection
      6. 7.3.6 N-Channel Buck Switch and Driver
      7. 7.3.7 Thermal Protection
      8. 7.3.8 Minimum Load Current
      9. 7.3.9 Ripple Configuration
    4. 7.4 Device Functional Modes
      1. 7.4.1 Standby Mode with VIN
      2. 7.4.2 Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      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 Custom Design With Excel Quickstart Tool
        3. 8.2.2.3 Feedback Resistors, RFB1 and RFB2
        4. 8.2.2.4 Switching Frequency Selection, RON
        5. 8.2.2.5 Buck Inductor, L1
        6. 8.2.2.6 Output Capacitor, COUT
        7. 8.2.2.7 Type I Ripple Circuit, RC
        8. 8.2.2.8 Input Capacitor, CIN
        9. 8.2.2.9 Current Limit, RCL
      3. 8.2.3 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 Custom Design With WEBENCH® Tools
      3. 11.1.3 Development Support
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
        1. 11.2.1.1 PCB Layout Resources
        2. 11.2.1.2 Thermal Design Resources
    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

8.2.2.8 Input Capacitor, CIN

The input capacitor should be large enough to limit the input voltage ripple that can be calculated using Equation 14.

Equation 14. LM5007 q_Cin_nvs252.gif

The input ripple reaches its maximum at D = 0.5. Targeting a ΔVCIN = 0.5 V at using a duty cycle of D = 0.5 results in CIN = 0.526 µF. A standard value of 1 µF is selected. The input capacitor should be rated for the maximum input voltage under all conditions. A 100-V, X7R type capacitor is selected for this design. The input capacitor should be placed close to the VIN pin and the anode of the diode (D1) as it supplies high-frequency switching current.

Also place a 0.1-µF bypass capacitor (CBYP) very close to VIN and RTN pins of the IC to reduce switching power loop parasitic inductance and mitigate SW node overshoot and ringing.