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

7 Summary

  • Older devices without dedicated ESD protection require external clamping to avoid exceeding input range.

  • Conventional ESD (CMOS or low voltage) input devices will clamp the inputs to the supplies with a diode and should not exceed the supplies.

  • "Fault Tolerant" or "Fail-Safe" inputs allow the input to exceed the supply up to a maximum voltage without damage, but the output may not be correct. Inputs remain high impedance.

  • "Above-The-Rails" inputs can exceed the supply voltage and are functional up to a maximum voltage, regardless of the supply voltage. Input bias current may increase or reverse when input is greater than the supply voltage.

  • Inputs that allow voltages above the supply voltage will need external clamps to avoid exceeding the maximum input voltage.

  • Avoid negative voltages on any pin (lower than V-).