• State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 2 answers
  • Subscribers 18 subscribers
  • Views 846 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

SN74LVC2244A: sn74lvc2240 short circuit current rating

Matthew MacDonald1
Prodigy 90 points
Part Number: SN74LVC2244A

What is the short circuit current rating for the SN74LVC2240A?

  • 0
    TI__Guru* 96681 points

    Hi Matthew,

    The SN74LVC2244A isn't characterized for short circuit current.  The recommended maximum output current is 12mA, although the device is likely capable of driving 50+ mA at a shorted output. Note that the absolute maximum rating of the device is 50mA per channel and 100mA total across all channels - so exceeding either of those values could damage the device.

  • 0 in reply to Emrys Maier
    Prodigy 90 points

    Hi Emrys


    Thanks for your reply. I came across a TI document called "Designing with Logic" SDYA009C. Table 2 in the document specifies the short circuit current (Ios) for several logic families. The SN74LVC240 was specified as 55mA. I would expect the SN74LVC2244A to be lower since it has 26 ohm equivalent resistors on its outputs. I have looked at several datasheets , for example the SN74LVC240, and have not seen the Ios numbers published. It seems that document SDYA009C is the only place the Ios numbers are published.

  • 0 in reply to Matthew MacDonald1
    Prodigy 90 points
    correction, the SN74LVC240 was specified as 85mA in document SDYA009C
  • 0 in reply to Matthew MacDonald1
    TI__Guru* 96681 points

    The output impedance of these devices (LVC family) typically are around 25 to 35 ohms. Assuming the worst case, the output would be ~50 ohms at 3.6V ~= 72mA @short circuit.

    As far as I know, there are only two reasons to add a series resistance to a signal line. One is to limit current, and the other is to improve signal integrity. The added resistor is really there to help with signal integrity -- ie to reduce ringing at the distant end.