SNOAA35F April   2019  – December 2024 LM2901 , LM2901B , LM2901B-Q1 , LM2903 , LM2903-Q1 , LM2903B , LM2903B-Q1 , LM339 , LM339-N , LM393 , LM393-N , LM393B , LM397 , TL331 , TL331-Q1 , TL331B

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Devices Covered in Application Note
    1. 1.1 Base Part Numbers
    2. 1.2 Input Voltage Offset Grades
    3. 1.3 Maximum Supply Voltage
    4. 1.4 High Reliability Options
  5. 2 The New TL331B, TL391B, LM339B, LM393B, LM2901B and LM2903B B Versions
  6. 3 PCN's to Change Classic Die to a New Die Design
    1. 3.1 PCN #1 for Single and Dual (TL331 and LMx93/LM2903)
    2. 3.2 PCN #2 for Single and Dual (TL331 and LMx93/LM2903)
    3. 3.3 PCN For Quad (LMx39, LM2901)
    4. 3.4 PCN for B Devices (including -Q1's)
    5. 3.5 Device PCN Summary
    6. 3.6 Determining Die Version Used
      1. 3.6.1 Determine Die Used for Single TL331 and Dual LM293, LM393, and LM2903 - PCN #1 (Ji3)
      2. 3.6.2 Determine Die Used for Single TL331 and Dual LM293, LM393, and LM2903 - PCN #2 (TiB)
      3. 3.6.3 Determine Die Used for Quad LM139, LM239, LM339, and LM2901
      4. 3.6.4 Determine Die Used for Post-PCN B Devices
  7. 4 Changes to Package Top Markings
  8. 5 Roughened Leadframe Finish
  9. 6 Input Considerations
    1. 6.1  Input Stage Schematic – The Classic LM339 Family
    2. 6.2  Input Stage Schematic - New "B" and TiB Devices
    3. 6.3  Differences Between the Classic, "B" and Tib Die Devices
    4. 6.4  Input Voltage Range
    5. 6.5  Input Voltage Range vs. Common Mode Voltage Range
    6. 6.6  Reason for Input Range Headroom Limitation
    7. 6.7  Input Voltage Range Feature
    8. 6.8  Both Inputs Above Input Range Behavior
    9. 6.9  Negative Input Voltages
      1. 6.9.1 Maximum Input Current
      2. 6.9.2 Phase Reversal or Inversion
      3. 6.9.3 Protecting Inputs from Negative Voltages
        1. 6.9.3.1 Simple Resistor and Diode Clamp
        2. 6.9.3.2 Voltage Divider with Clamp
          1. 6.9.3.2.1 Split Voltage Divider with Clamp
    10. 6.10 Power-Up Behavior
    11. 6.11 Capacitors and Hysteresis
    12. 6.12 Output to Input Cross-Talk
  10. 7 Output Stage Considerations
    1. 7.1 Output VOL and IOL
    2. 7.2 Pull-Up Resistor Selection
    3. 7.3 Short Circuit Sinking Current
    4. 7.4 Pulling Output Up Above Vcc
    5. 7.5 Negative Voltages Applied to Output
    6. 7.6 Adding Large Filter Capacitors To Output
  11. 8 Power Supply Considerations
    1. 8.1 Supply Bypassing
      1. 8.1.1 Low VCC Guidance
      2. 8.1.2 Split Supply use
  12. 9 General Comparator Usage
    1. 9.1 Unused Comparator Connections
      1. 9.1.1 Do Not Connect Inputs Directly to Ground
      2. 9.1.2 Unused Comparator Input Connections
      3. 9.1.3 Leave Outputs Floating
      4. 9.1.4 Prototyping
  13. 10PSpice and TINA TI Models
  14. 11Conclusion
  15. 12Related Documentation
    1. 12.1 Related Links
  16. 13Revision History

6.7 Input Voltage Range Feature

A nice feature of the LM339 family (and ONLY applies to the LM339 family devices listed in Table 1-2) is that only one input needs to be within the valid input voltage range for a valid output. The other input can be above the input voltage range or, even above VCC and the output maintains the correct state.

Note: The following feature was originally intended to reassure users of expected behavior during fault conditions or transient conditions. The feature is described here only because the functionality has been mentioned in the data sheets over the years. TI strongly advises to stay within the specified input voltage range limits and not to rely on the following feature as part of normal operating conditions. The device does not meet full data sheet specifications in this mode.

This occurs because as long as one of the inputs is still within the valid input voltage range, that input pairs tail current (I1 or I2) is still flowing, signaling the correct output polarity to the active loads Q5 and Q6.

While this is a nice feature, the feature does come at a cost. When operating outside the specified input voltage limits, performance deteriorates and no longer meets the data sheet specifications. Critical specifications such as offset voltage, bias current and propagation delay are adversely affected. TI still recommends to stay within the data sheet input voltage range specifications.