SNVS780E May   1998  – December 2016 LM337L

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
    6. 6.6 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 Output Voltage Adjustment
    4. 7.4 Device Functional Modes
      1. 7.4.1 Protection Diodes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 1.2-V to 25-V Adjustable Regulator
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curve
      2. 8.2.2 Regulator With Trimmable Output Voltage
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
  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 Documentation Support
      1. 11.1.1 Related Documentation
    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

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

8 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.

8.1 Application Information

The LM337L is a negative output linear regulator with high accuracy and a wide temperature range. An output capacitor can be added to further improve transient response, and the ADJ pin can be bypassed to achieve very high ripple-rejection ratios. The device's functionality can be utilized in many different applications that require negative voltage supplies, such as bipolar amplifiers, operational amplifiers, and constant current regulators.

8.2 Typical Applications

8.2.1 1.2-V to 25-V Adjustable Regulator

LM337L 00913403.gif
Full output current not available at high input-output voltages
†C1 = 1-μF solid tantalum or 10-μF aluminum electrolytic required for stability
*C2 = 1-μF solid tantalum is required only if regulator is more than 4″ from power supply filter capacitor
Figure 6. 1.2-V to 25-V Adjustable Regulator Diagram

8.2.1.1 Design Requirements

The device component count is very minimal, employing two resistors as part of a voltage divider circuit and an output capacitor for load regulation. An input capacitor is needed if the device is more than 4 in. from the filter capacitors.

8.2.1.2 Detailed Design Procedure

The output voltage is set based on the selection of the two resistors (R1 and R2) as shown in Equation 1.

Equation 1. LM337L 00913405.gif

8.2.1.3 Application Curve

LM337L app_curve_SNVS780.gif Figure 7. Dropout Voltage across Load Current at 25°C (∆Vout < 100 mV

8.2.2 Regulator With Trimmable Output Voltage

LM337L 00913404.gif Figure 8. Regulator with Trimmable Output Voltage Diagram

8.2.2.1 Design Requirements

This design uses five resistors with two being used for a voltage divider circuit and the other three used for trimming the output voltage. The benefit is lower cost as compared to using a trim pot. An output capacitor is needed to improve load regulation.

8.2.2.2 Detailed Design Procedure

This design will trim the output voltage to within 1% of –22 V. The parallel combination of R1, R3, R4 and R5 serve as the bottom resistance and R2 as the top resistance in the voltage divider that sets the output voltage.

Trim Procedure:

  • If VOUT is –23.08 V or larger, do not use R3, otherwise leave it in.
  • Then if VOUT is –22.47 V or bigger, do not use R4, otherwise leave it in.
  • Then if VOUT is –22.16 V or bigger, do not use R5, otherwise leave it in.
This will trim the output to well within 1% of –22 VDC, without any of the expense or trouble of a trim pot (see LB-46). This technique can be used at any output voltage level.