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

7.1 Output VOL and IOL

A critical graph for the output is the Output voltage vs Output Current graph, shown in Figure 7-1. From this graph, the output Low voltage can be determined from the expected sinking load current.

Typical Output Low (Saturation) Voltage vs Output Sinking CurrentFigure 7-1 Typical Output Low (Saturation) Voltage vs Output Sinking Current

The graph also shows the current limit, where the output voltage sharply inflects upwards in the 10-20mA region. This region must be avoided as the specified minimum short circuit current is only 6mA (typically 12-16mA) and can vary across devices, lots and temperature. TI recommends sinking currents of less than 5mA.

This graph must also be used to determine the pull-up resistor value needed for a desired output low voltage.

For example, if a 3.3kΩ resistor is used on a 3.3V pull-up voltage, the resulting current is 1mA when sinking. From the graph, 1mA results in a worst-case (125°C) VOL voltage of 90mV. However, if a 330Ω pull-up resistor is used, the output low voltage is now 350mV, and is also uncomfortably close to the current limit.