SNVS778E May   1999  – January 2016 LM137 , LM337-N

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 Thermal Regulation
    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 Adjustable Negative Voltage 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 Adjustable Lab Voltage Regulator
      3. 8.2.3 Current Regulator
      4. 8.2.4 −5.2-V Regulator with Electronic Shutdown
      5. 8.2.5 High Stability −10-V Regulator
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
      1. 10.3.1 Heatsinking SOT-223 Package Parts
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Related Links
    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

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 LM137 and LM337-N are versatile, high performance, negative output linear regulators 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 Adjustable Negative Voltage Regulator

The LM137 and LM337-N can be used as a simple, negative output regulator to enable a variety of output voltages needed for demanding applications. By using an adjustable R2 resistor, a variety of negative output voltages can be made possible as shown in Figure 16.

LM137 LM337-N 00906701.png
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 inches from power-supply filter capacitor
Output capacitors in the range of 1 μF to 1000 μF of aluminum or tantalum electrolytic are commonly used to provide improved output impedance and rejection of transients
Figure 16. Adjustable Negative Voltage Regulator
Equation 2. LM137 LM337-N eq1_snvs778.gif

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 inches 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 Figure 16.

8.2.1.3 Application Curve

As shown in Figure 17, the maximum output current capability is limited by the input-output voltage differential, package type, and junction temperature.

LM137 LM337-N 00906717.png Figure 17. Current Limit

8.2.2 Adjustable Lab Voltage Regulator

The LM337-N can be combined with a positive regulator such as the LM317-N to provide both a positive and negative voltage rail. This can be useful in applications that use bi-directional amplifiers and dual-supply operational amplifiers.

LM137 LM337-N 00906709.png
Full output current not available at high input-output voltages
*The 10 μF capacitors are optional to improve ripple rejection

8.2.3 Current Regulator

A simple, fixed current regulator can be made by placing a resistor between the VOUT and ADJ pins of the LM137. By regulating a constant 1.25 V between these two terminals, a constant current can be delivered.

LM137 LM337-N 00906711.png
Equation 3. LM137 LM337-N eq2_snvs778.gif
Equation 4. LM137 LM337-N eq3_snvs778.gif

8.2.4 −5.2-V Regulator with Electronic Shutdown

The LM337-N can be used with a PNP transistor to provide shutdown control from a TTL control signal. The PNP can short or open the ADJ pin to GND. When ADJ is shorted to GND by the PNP, the output is −1.3V. When ADJ is disconnected from GND by the PNP, then the LM337-N outputs the programmed output of −5.2 V.

LM137 LM337-N 00906710.png
Minimum output ≃ −1.3 V when control input is low

8.2.5 High Stability −10-V Regulator

Using a high stability shunt voltage reference in the feedback path, such as the LM329, provides damping necessary for a stable, low noise output.

LM137 LM337-N 00906714.png