SLVS047L November   1981  – January 2015 LM237 , LM337

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified Schematic
  5. 5 Revision History
  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
    6. 7.6 Electrical Characteristics
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Design Schematic
    4. 8.4 Feature Description
      1. 8.4.1 Output Voltage Adjustment
    5. 8.5 Device Functional Modes
      1. 8.5.1 Adjustable Output Mode
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 General Configurations
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    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

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

9.1 Application Information

9.1.1 General Configurations

fig2_lvs047.gifFigure 2. Current-Limiting Circuit

This application uses the LMx37 device's reference voltage, combined with the series resistor RS, to limit the current to 1.25 V ÷ RS

9.2 Typical Application

fig1_lvs047.gifFigure 3. Adjustable Negative-Voltage Regulator

9.2.1 Design Requirements

  • 1-µF solid tantalum on the input pin if the regulator is more than 10 cm from the power supply filter capacitor
  • 1-µF solid tantalum or 10-µF aluminum electrolytic capacitor is required on the output pin for stability.
  • R1, which is usually 120 Ω as part of the resistor divider.
  • R2, which can be varied to change the value of VO.

9.2.2 Detailed Design Procedure

VO is determined by the values of R1 and R2. Choosing R1 = 120 Ω means that about 10.42 mA of current will flow through R1. The ~10 mA of current satisfies the minimum operating current and renders IREF negligible. Since the current is coming from ground, the same amount of current will flow through R2. Therefore, the size of R2 will be the dominant factor in adjusting VO. The relationship between R1, R2, and VO is as follows:

Equation 1. eq_R2_lvs047.gif

where

    9.2.3 Application Curves

    D001_SLVS047.gifFigure 4. Ripple Rejection Over Frequency