SNVS123D April   1998  – May 2016 LM2599

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics - 3.3-V Version
    6. 7.6  Electrical Characteristics - 5-V Version
    7. 7.7  Electrical Characteristics - 12-V Version
    8. 7.8  Electrical Characteristics - Adjustable Voltage Version
    9. 7.9  Electrical Characteristics - All Output Voltage Versions
    10. 7.10 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Shutdown/Soft-Start
      2. 8.3.2 Inverting Regulator
      3. 8.3.3 Undervoltage Lockout
      4. 8.3.4 Negative Voltage Charge Pump
    4. 8.4 Device Functional Modes
      1. 8.4.1 Discontinuous Mode Operation
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Soft-Start Capacitor (CSS)
      2. 9.1.2 Delay Capacitor (CDELAY)
        1. 9.1.2.1 RPULLUP
      3. 9.1.3 Feedforward Capacitor (CFF) for Adjustable Output Voltage Version Only
      4. 9.1.4 Input Capacitor (CIN)
      5. 9.1.5 Output Capacitor (COUT)
      6. 9.1.6 Catch Diode
      7. 9.1.7 Inductor Selection
      8. 9.1.8 Output Voltage Ripple and Transients
      9. 9.1.9 Open Core Inductors
    2. 9.2 Typical Applications
      1. 9.2.1 Fixed Output Voltage Version
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Inductor Selection (L1)
          2. 9.2.1.2.2 Output Capacitor Selection (COUT)
          3. 9.2.1.2.3 Catch Diode Selection (D1)
          4. 9.2.1.2.4 Input Capacitor (CIN)
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Adjustable Output Voltage Version
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Programming Output Voltage
          2. 9.2.2.2.2 Inductor Selection (L1)
          3. 9.2.2.2.3 Output Capacitor Selection (COUT)
          4. 9.2.2.2.4 Feedforward Capacitor (CFF)
          5. 9.2.2.2.5 Catch Diode Selection (D1)
          6. 9.2.2.2.6 Input Capacitor (CIN)
        3. 9.2.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
    3. 11.3 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Community Resources
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

6 Pin Configuration and Functions

NDZ Package
7-Pin TO-220
Top View
LM2599 01258250.png
KTW Package
7-Pin TO-263
Top View
LM2599 01258223.png

Pin Functions(1)

PIN I/O DESCRIPTION
NO. NAME
1 +VIN I This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor must be present at this pin to minimize voltage transients and to supply the switching currents needed by the regulator.
2 Output O Internal switch. The voltage at this pin switches between approximately (+VIN − VSAT) and approximately −0.5 V, with a duty cycle of VOUT/VIN. To minimize coupling to sensitive circuitry, the PCB copper area connected to this pin must be kept to a minimum.
3 Error Flag O Open-collector output that provides a low signal (flag transistor ON) when the regulated output voltage drops more than 5% from the nominal output voltage. On start up, Error Flag is low until VOUT reaches 95% of the nominal output voltage and a delay time determined by the Delay pin capacitor. This signal can be used as a reset to a microprocessor on power-up.
4 Ground — Circuit ground.
5 Delay O At power-up, this pin can be used to provide a time delay between the time the regulated output voltage reaches 95% of the nominal output voltage, and the time the error flag output goes high.
6 Feedback I Senses the regulated output voltage to complete the feedback loop.
7 Shutdown/Soft-start I This dual function pin provides the following features: (a) Allows the switching regulator circuit to be shut down using logic level signals thus dropping the total input supply current to approximately 80 μA. (b) Adding a capacitor to this pin provides a soft-start feature which minimizes start-up current and provides a controlled ramp up of the output voltage.
(1) If any of the above three features (Shutdown/Soft-start, Error Flag, or Delay) are not used, the respective pins must be left open.