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

4 How to Determine the ESD Structure of the Device from the Data Sheet

How can you know what type of protection the op amp has? The effectiveness of the ESD protection is listed on the data sheet in the ESD ratings table. This specification is developed by applying an emulated ESD pulse to all the device pins and checking for damage. The ESD event is generated by special test equipment that creates a controlled ESD pulse with the same charge, voltage levels, inductance, resistance, and capacitance of a real-world situation. Typically, the real-world situation being emulated is the human-body or charged-device in contact with a low impedance. This was mentioned earlier in a previous section. The ESD voltage levels specified in Table 4-1 reflect the maximum ESD voltage that was applied without damaging the device TLV9141.

Table 4-1 TLV9141 ESD Ratings
VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1) ±4000 V
Charged-device model (CDM), per ANSI/ESDA/JEDEC JS-002 (2) ±1500
(1) JEDEC document JEP155 states that 500V HBM allows safe manufacturing with a standard ESD control process
(2) JEDEC document JEP157 states that 250V CDM allows safe manufacturing with a standard ESD control process.

There are two ways to know if a particular device contains ESD protection diodes or relies upon another method to achieve ESD robustness. Look at the Absolute Maximum Ratings table, or in some cases you can find a functional block diagram that illustrates the diodes. In the Absolute Maximum Ratings table, when the input voltage range is limited to approximately 0.5V beyond the supply range, then the device contains dual diode configuration ESD diodes (see Table 4-2). This is due to the forward bias voltage of a diode generally being around 0.5V. If the input signal stays inside this range the ESD diodes does not turn on. This type of protection generally also provides an input current limit of ±10mA.

Table 4-2 TLV2888 Absolute Maximum Ratings (Dual Diode Example)
MIN MAX UNIT
VS Supply voltage, VS = (V+) – (V–) 26 V
Input voltage Common-mode (V–) –0.5 (V+) + 0.5 V
Differential (V+) – (V–) + 0.2
Output short-circuit (1) Continuous
TJ Operating junction temperature -40 150 °C
Tstg Storage temperature -65 150 °C
(1) Short-circuit to ground, one amplifier per package.

If the device is using a transient or level triggered protection, the input voltage range usually goes up to the maximum recommended power supply voltage operating conditions. This is shown below using the LM2904B data sheet (see Table 4-3).

Table 4-3 LM2904BQ Absolute Maximum Ratings (Level Triggered Example) over operating ambient temperature range (unless otherwise noted)(1)
MIN MAX UNIT
Supply voltage, VS = ([V+] – [V–]) 40 V
Differential input voltage, VID(2) –32 32 V
Input voltage, VI Either input –0.3 40 V
Duration of output short circuit (one amplifier) to V– at (or below) TA = 25°C,
VS ≤ 15V (3)		 Unlimited s
Operating ambient temperature, TA –40 125 °C
Operating virtual-junction temperature, TJ 150 °C
Storage temperature, Tstg –65 150 °C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods can affect device reliability.
(2) Differential voltages are at IN+, with respect to IN−.

3) Short circuits from outputs to the supply pins can cause excessive heating and eventual destruction.

Another simple way to determine the internal ESD protection scheme is to look at the functional block diagram of the device. The data sheet often contains this, and the internal diodes are frequently included in the functional block diagram. This was previously seen from Figure 3-2, the functional block diagram for OPA928.