SPVA018 August   2025 LM2904B

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2ESD Overview
    1. 2.1 What is Electrostatic Discharge?
      1. 2.1.1 ESD Cell Robustness in Semiconductors
  6. 3Types of ESD Cells
    1. 3.1 Dual Diode Configuration
      1. 3.1.1 Why Not Always Use Dual Diode Configuration?
    2. 3.2 Bootstrapped Diodes
    3. 3.3 Absorption Devices
      1. 3.3.1 Active Clamps
      2. 3.3.2 GCNMOS Clamps
    4. 3.4 Silicon Controlled Rectifiers
    5. 3.5 CER and ECR NPN Diodes
      1. 3.5.1 Measuring the Response of an ECR and CER ESD Cell
    6. 3.6 Comparison of ESD Cells
  7. 4How to Determine the ESD Structure of the Device from the Data Sheet
  8. 5How to Protect The System from In Circuit ESD/EOS Events
    1. 5.1 Using TVS Diodes and Series Resistance for Circuit Protection
    2. 5.2 Using Schottky Diodes for Circuit Protection
  9. 6How to Test an Op Amp in a System Level Circuit
    1. 6.1 ESD Protection Cell Advancements Over the Years
  10. 7Summary
  11. 8References

1 Introduction

Op amps can be damaged by electrostatic discharge (ESD) or other types of electrical overstress (EOS) events. The internal op amp device has ESD protection structures (called ESD cells) that are designed to protect against out of circuit ESD events. Out-of-circuit refers to the ESD applied to the device during the assembly and test process before it is soldered to a PCB. In some instances the ESD protection structures can also protect against in circuit ESD as well as other forms of EOS. However, it is important to understand what type of ESD cells are used, to understand how they behave versus overstress events. Furthermore, it is often necessary to add external components such as resistors, TVS diodes, and Schottky diodes to improve the robustness against overstress signals. Finally, knowing the type of ESD cells used can be important in board level product testing as different ESD cells have different characteristics for board level tests. This document describes the different ESD cells, and explain how to use these ESD cells with external components to protect the amplifier. The document also explains the general characteristics of the ESD cells that are normally seen in board level product tests.