SNVS121E May   1996  – May 2019 LM2586

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Typical Applications
  3. 3 Description
    1.     Device Images
      1.      Block Diagram
  4. 4 Revision History
  5. 5 Pin Configurations
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Ratings
    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: Adjustable
    9. 6.9 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 Flyback Regulator Operation
      2. 7.3.2 Step-Up (Boost) Regulator Operation
      3. 7.3.3 Programming Output Voltage (Selecting R1 And R2)
      4. 7.3.4 Shutdown Control
      5. 7.3.5 Frequency Adjustment
      6. 7.3.6 Frequency Synchronization
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Typical Flyback Regulator Applications
        1. 8.2.1.1 Design Requirements
          1. 8.2.1.1.1 Transformer Selection (T)
          2. 8.2.1.1.2 Transformer Footprints
        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 Flyback Regulator Input Capacitors
          3. 8.2.1.2.3 Switch Voltage Limits
          4. 8.2.1.2.4 Output Voltage Limitations
          5. 8.2.1.2.5 Noisy Input Line Condition
          6. 8.2.1.2.6 Stability
      2. 8.2.2 Typical Boost Regulator Applications
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
    3. 8.3 System Examples
      1. 8.3.1 Test Circuits
  9. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
  10. 10Heat Sink/Thermal Considerations
  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 Receiving Notification of Documentation Updates
    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

7.3.2 Step-Up (Boost) Regulator Operation

Figure 20 shows the LM2586 used as a step-up (boost) regulator. This is a switching regulator that produces an output voltage greater than the input supply voltage.

A brief explanation of how the LM2586 boost regulator works is as follows (refer to Figure 20). When the NPN switch turns on, the inductor current ramps up at the rate of VIN/L, storing energy in the inductor. When the switch turns off, the lower end of the inductor flies above VIN, discharging its current through diode (D) into the output capacitor (COUT) at a rate of (VOUT − VIN)/L. Thus, energy stored in the inductor during the switch on time is transferred to the output during the switch off time. The output voltage is controlled by adjusting the peak switch current, as described in .

LM2586 01251651.pngFigure 20. 12-V Boost Regulator

By adding a small number of external components (as shown in Figure 20), the LM2586 can be used to produce a regulated output voltage that is greater than the applied input voltage. The switching waveforms observed during the operation of this circuit are shown in Figure 21. Typical performance of this regulator is shown in Figure 22.

LM2586 01251667.png
A: Switch Voltage,10V/div

B: Switch Current, 2A/div

C: Inductor Current, 2A/div

D: Output Ripple Voltage,100 mV/div, AC-Coupled
Figure 21. Switching Waveforms
LM2586 01251668.png
Figure 22. VOUT Response To Load Current Step