SNVS093G June   1999  – May 2015 LM2990

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: -5 V and -5.2 V
    6. 6.6 Electrical Characteristics: -12 V and -15 V
    7. 6.7 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 Fixed Output-Voltage Options
      2. 7.3.2 Low Dropout Voltage
      3. 7.3.3 Short Circuit Protection (Current Limit)
      4. 7.3.4 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation with VOUT(TARGET) -5 V ≥ VIN > -26 V
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 -5 V Post Regulator for an Isolated Switching Power Supply
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 External Capacitors
          2. 8.2.1.2.2 Forcing The Output Positive
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Fixed or Adjustable Current Sink
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 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 Device Nomenclature
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • Input Voltage: –26 V to –6 V
  • Fixed Output Voltages: −5 V, −5.2 V, −12 V, and −15 V
  • 5% Output Accuracy over Entire Operating Range
  • Output Current in Excess of 1 A
  • Dropout Voltage Typically 0.6 V at 1-A Load
  • Low Quiescent Current
  • Internal Short-Circuit Current Limit
  • Internal Thermal Shutdown with Hysteresis
  • Functional Complement to the LM2940 Series

2 Applications

  • Post Switcher Regulator
  • Local, On-Card Regulation
  • Battery Operated Equipment

Typical Application

LM2990 1080101.png
* and **: Required for stability. Must be at least a 10-μF aluminum electrolytic or a 1-μF solid tantalum to maintain stability. May be increased without bound to maintain regulation during transients. Locate the capacitor as close as possible to the regulator. The equivalent series resistance (ESR) is critical, and should be less than 10 Ω over the same operating temperature range as the regulator.

3 Description

The LM2990 is a three-terminal, low-dropout, 1-A negative voltage regulator available with fixed output voltages of −5 V, −5.2 V, −12 V, and −15 V.

The LM2990 uses circuit design techniques to provide low-dropout and low-quiescent current. The dropout voltage at 1-A load current is typically 0.6 V and an ensured worst-case maximum of 1 V over the entire operating temperature range. The quiescent current is typically 1 mA with 1-A load current and an input-output voltage differential greater than 3 V. A unique circuit design of the internal bias supply limits the quiescent current to only 9 mA (typical) when the regulator is in the dropout mode (VOUT − VIN ≤ 3 V). Output voltage accuracy is ensured to ±5% over load and temperature extremes.

The LM2990 also implements short-circuit proof, and thermal shutdown includes hysteresis to enhance the reliability of the device when overloaded for an extended period of time.

All these features make the LM2990 an ideal negative power supply suited for dual supply systems. The device may also be used as fixed or adjustable current sink load.

The LM2990 is available in two 3-pin packages and is rated for operation over the junction temperature range of −40°C to 125°C.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM2990 DDPAK/TO-263 (3) 10.20 mm x 9.00 mm
TO-220 (3) 14.99 mm x 10.16 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.