SNOAA91 may   2023 TLV1812 , TLV1851 , TLV7011

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Input Types
    1. 2.1 Classic Bipolar Inputs
    2. 2.2 ESD Protected Inputs
    3. 2.3 "Fail-Safe" and "Fault Tolerant" Inputs
      1. 2.3.1 LM339 Family - The Original "Fail-Safe" Input
      2. 2.3.2 Modern "Fail-Safe" Inputs
    4. 2.4 "Over-the-Rail" Inputs
  6. 3Identifying The Difference Between The Input Types
    1. 3.1 Older Bipolar Device Inputs
    2. 3.2 Identifying ESD Clamped Inputs
    3. 3.3 Identifying "Failsafe" or "Over-The-Rail" Inputs
  7. 4Precautions for "Failsafe" and "Over-The-Rail" Inputs
  8. 5Negative Input Voltages
  9. 6Input Types Comparison Table
  10. 7Summary
  11. 8References

2.3 "Fail-Safe" and "Fault Tolerant" Inputs

"Fault Tolerant" and "Fail-Safe" have been used interchangeably across several device families. These terms are essentially the same and can be used interchangeably within this paper.

"Fault Tolerant" and "Fail-Safe" inputs are defined as being able to be pulled-up to a maximum voltage, without damage, and will remain high impedance, even when Vcc is zero.

Care must be taken when both inputs are taken above the specified valid input range as the output can be indeterminate. Please consult the Detailed Description or Application Information section of the data sheet for information on the tendency of the output behavior.

These input types do not have the "upper" ESD clamping diode to the positive supply. If any ESD protection is provided, it is usually a snapback or zener-type clamp to the negative supply only.