SNVS107G June   1999  – March 2023 LM2576 , LM2576HV

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 Information
    5. 6.5  Electrical Characteristics: 3.3 V
    6. 6.6  Electrical Characteristics: 5 V
    7. 6.7  Electrical Characteristics: 12 V
    8. 6.8  Electrical Characteristics: 15 V
    9. 6.9  Electrical Characteristics: Adjustable Output Voltage
    10. 6.10 Electrical Characteristics: All Output Voltage Versions
    11. 6.11 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 Undervoltage Lockout
      2. 7.3.2 Delayed Start-Up
      3. 7.3.3 Adjustable Output, Low-Ripple Power Supply
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
      3. 7.4.3 Current Limit
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Input Capacitor (CIN)
      2. 8.1.2  Inductor Selection
      3. 8.1.3  Inductor Ripple Current
      4. 8.1.4  Output Capacitor
      5. 8.1.5  Catch Diode
      6. 8.1.6  Output Voltage Ripple and Transients
      7. 8.1.7  Feedback Connection
      8. 8.1.8  ON /OFF INPUT
      9. 8.1.9  Inverting Regulator
      10. 8.1.10 Negative Boost Regulator
    2. 8.2 Typical Applications
      1. 8.2.1 Fixed Output Voltage Version
        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 Inductor Selection (L1)
          3. 8.2.1.2.3 Output Capacitor Selection (COUT)
          4. 8.2.1.2.4 Catch Diode Selection (D1)
          5. 8.2.1.2.5 Input Capacitor (CIN)
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Adjusted Output Voltage Version
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Programming Output Voltage
          2. 8.2.2.2.2 Inductor Selection (L1)
          3. 8.2.2.2.3 Output Capacitor Selection (COUT)
          4. 8.2.2.2.4 Catch Diode Selection (D1)
          5. 8.2.2.2.5 Input Capacitor (CIN)
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
      3. 8.4.3 Grounding
      4. 8.4.4 Heat Sink and Thermal Considerations
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Device Nomenclature
        1. 9.1.1.1 Definition of Terms
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design with WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Support Resources
    4. 9.4 Receiving Notification of Documentation Updates
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • NDH|5
  • NEB|5
  • KTT|5
  • KC|5
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.1.6 Output Voltage Ripple and Transients

The output voltage of a switching power supply contains a sawtooth ripple voltage at the switcher frequency, typically about 1% of the output voltage, and can also contain short voltage spikes at the peaks of the sawtooth waveform.

The output ripple voltage is due mainly to the inductor sawtooth ripple current multiplied by the ESR of the output capacitor (see Section 8.1.2).

The voltage spikes are present because of the fast switching action of the output switch, and the parasitic inductance of the output filter capacitor. To minimize these voltage spikes, special low inductance capacitors can be used, and their lead lengths must be kept short. Wiring inductance, stray capacitance, as well as the scope probe used to evaluate these transients, all contribute to the amplitude of these spikes.

An additional small LC filter (20 μH and 100 μF) can be added to the output (as shown in Figure 7-4) to further reduce the amount of output ripple and transients. A 10 × reduction in output ripple voltage and transients is possible with this filter.