This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM319-N: Datasheet differences

Part Number: LM319-N
Other Parts Discussed in Thread: LM339, TLV1702

The Datasheet from Linear shows that there are Input Protection Diodes for the LM319.

However, the TI datasheet does not. Does the TI Chip contain those Input Protection Diodes?

www.ti.com/.../snosbj2b.pdf

  • Hello Hansel,

    No. The TI/National version does not have protection diodes across the inputs. LT added these diodes to their device.

    The NPN input devices used have a low breakdown voltage, so the Abs Max differential (voltage *between* input pins) is 5V.
  • Thanks for the quick response Paul.

    What will be the consequences of violating the Abs Max differential? ie; An 8 volt differential instead of 5.
  • Hello Hansel,

    Exceeding the Abs Max voltage can damage the base-emitter junctions of the input stage transistors, which would cause changes in offset and possibly response time.

    8V is into the damage territory - especially if current is not limited. Long term reliability (lifetime) will be affected.

    Don't do it!!

    You can add a 5V (or less) Zener externally (similar to what Linear did internally) along with series resistors to limit the current. Of course, this would cause the inputs to be clamped together when the differential voltage exceeds 5V. Your circuit would need to be reviewed to make sure this would not cause problems.

  • Thanks Paul,

    I'm currently using the LM319 because of the following:

    • Fast Comparator (Under 1 us)
    • Supply Voltage can handle 0V to 15V
    • Reference Voltage of 10V

    However, I do need the negative input voltage to be able to go from 0-15 Volts, which due to the Differential Input Voltage and Minimum Input Voltage (with a 0-15V supply) the LM319 doesn't work too well.

    Would you have any recommendations for another open collector comparator that can do this? Most 15V comparators seem to have the same problems as the LM319. Maybe the LM339?

    Best Regards,

    Hansel Qiu

  • The TLV1702 should work for you. It has rail to rail input capability and meets the other criteria.