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

9.1.1.1 Definition of Terms

    BUCK REGULATORA switching regulator topology in which a higher voltage is converted to a lower voltage. Also known as a step-down switching regulator.
    BUCK-BOOST REGULATORA switching regulator topology in which a positive voltage is converted to a negative voltage without a transformer.
    DUTY CYCLE (D)Ratio of the output switch on-time to the oscillator period. For buck regulator:
    Equation 16. D= tONT=VOUTVIN
     For buck-boost regulator:
    Equation 17. D= tONT=VOUTVOUT+VIN
    CATCH DIODE OR CURRENT STEERING DIODEThe diode which provides a return path for the load current when the LM2576 switch is OFF.
    EFFICIENCY (η)The proportion of input power actually delivered to the load.
    Equation 18. η= POUTPIN=POUTPOUT+PLOSS
    CAPACITOR EQUIVALENT SERIES RESISTANCE (ESR)The purely resistive component of a real capacitor impedance (see Figure 9-1). It causes power loss resulting in capacitor heating, which directly affects the capacitor operating lifetime. When used as a switching regulator output filter, higher ESR values result in higher output ripple voltages.
    GUID-A9D4BCB3-5A9B-4589-8976-3E719D21E14D-low.pngFigure 9-1 Simple Model of a Real Capacitor

    Most standard aluminum electrolytic capacitors in the 100 μF–1000 μF range have 0.5Ω to 0.1Ω ESR. Higher-grade capacitors (low-ESR, high-frequency, or low-inductance) in the 100 μF to 1000 μF range generally have ESR of less than 0.15Ω.

    EQUIVALENT SERIES INDUCTANCE (ESL)The pure inductance component of a capacitor (see Figure 9-1). The amount of inductance is determined to a large extent on the capacitor construction. In a buck regulator, this unwanted inductance causes voltage spikes to appear on the output.
    OUTPUT RIPPLE VOLTAGEThe AC component of the switching regulator output voltage. It is usually dominated by the output capacitor ESR multiplied by the inductor ripple current (ΔIIND). The peak-to-peak value of this sawtooth ripple current can be determined by reading Section 8.1.3.
    CAPACITOR RIPPLE CURRENTRMS value of the maximum allowable alternating current at which a capacitor can be operated continuously at a specified temperature.
    STANDBY QUIESCENT CURRENT (ISTBY)Supply current required by the LM2576 when in the standby mode ( ON /OFF pin is driven to TTL-high voltage, thus turning the output switch OFF).
    INDUCTOR RIPPLE CURRENT (ΔIIND)The peak-to-peak value of the inductor current waveform, typically a sawtooth waveform when the regulator is operating in the continuous mode (vs. discontinuous mode).
    CONTINUOUS/DISCONTINUOUS MODE OPERATIONRelates to the inductor current. In the continuous mode, the inductor current is always flowing and never drops to zero, vs. the discontinuous mode, where the inductor current drops to zero for a period of time in the normal switching cycle.
    INDUCTOR SATURATIONThe condition which exists when an inductor cannot hold any more magnetic flux. When an inductor saturates, the inductor appears less inductive and the resistive component dominates. Inductor current is then limited only by the DC resistance of the wire and the available source current.
    OPERATING VOLT MICROSECOND CONSTANT (E•Top)The product (in VoIt•μs) of the voltage applied to the inductor and the time the voltage is applied. This E•Top constant is a measure of the energy handling capability of an inductor and is dependent upon the type of core, the core area, the number of turns, and the duty cycle.