SLOS066W September   1975  – March 2015 LM124 , LM124A , LM224 , LM224A , LM224K , LM224KA , LM2902 , LM2902K , LM2902KAV , LM2902KV , LM324 , LM324A , LM324K , LM324KA


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  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 for LMx24 and LM324K
    6. 6.6 Electrical Characteristics for LM2902 and LM2902V
    7. 6.7 Electrical Characteristics for LMx24A and LM324KA
    8. 6.8 Operating Conditions
    9. 6.9 Typical Characteristics
  7. Parameter Measurement Information
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Unity-Gain Bandwidth
      2. 8.3.2 Slew Rate
      3. 8.3.3 Input Common Mode Range
    4. 8.4 Device Functional Modes
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Related Links
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information



11 Layout

11.1 Layout Guidelines

For best operational performance of the device, use good PCB layout practices, including:

  • Noise can propagate into analog circuitry through the power pins of the circuit as a whole, as well as the operational amplifier. Bypass capacitors are used to reduce the coupled noise by providing low impedance power sources local to the analog circuitry.
    • Connect low-ESR, 0.1-μF ceramic bypass capacitors between each supply pin and ground, placed as close to the device as possible. A single bypass capacitor from V+ to ground is applicable for single supply applications.
  • Separate grounding for analog and digital portions of circuitry is one of the simplest and most-effective methods of noise suppression. One or more layers on multilayer PCBs are usually devoted to ground planes. A ground plane helps distribute heat and reduces EMI noise pickup. Make sure to physically separate digital and analog grounds, paying attention to the flow of the ground current.
  • To reduce parasitic coupling, run the input traces as far away from the supply or output traces as possible. If it is not possible to keep them separate, it is much better to cross the sensitive trace perpendicular as opposed to in parallel with the noisy trace.
  • Place the external components as close to the device as possible. Keeping RF and RG close to the inverting input minimizes parasitic capacitance, as shown in Layout Examples.
  • Keep the length of input traces as short as possible. Always remember that the input traces are the most sensitive part of the circuit.
  • Consider a driven, low-impedance guard ring around the critical traces. A guard ring can significantly reduce leakage currents from nearby traces that are at different potentials.

11.2 Layout Examples

LM124 LM124A LM224 LM224A LM224K LM224KA LM324 LM324A LM324K LM324KA LM2902 LM2902V LM2902K LM2902KV LM2902KAV layout2.gifFigure 11. Operational Amplifier Board Layout for Noninverting Configuration
LM124 LM124A LM224 LM224A LM224K LM224KA LM324 LM324A LM324K LM324KA LM2902 LM2902V LM2902K LM2902KV LM2902KAV layout1.gifFigure 12. Operational Amplifier Schematic for Noninverting Configuration