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SN7406: sn7406 vs sn74ls06

zrno soli
Guru 34333 points
Part Number: SN7406
Other Parts Discussed in Thread: SN74LS06, SN74LVC1G07,

Hi,

There are more than 2 devices that share (over the cable) same bus. Each bus line is pulled high to 5V over 1k resistor, and for low value is used 7406. I am adding new device to the same bus. Can I use sn74ls06 instead of non ls device? I checked datasheet and both (ls and non ls) have almost the same switching characteristics. On device input is 3.3V signal from microcontroller pin (few mA) and device output is connected to bus (over the cable).

Regards,

JH

  • +1
    Guru 271290 points

    SN74LSxx devices are designed to be compatible with SN74xx devices (except for the power consumption).

    If you have only a single line, consider a smaller device like the SN74LVC1G07.

  • 0 in reply to Clemens Ladisch
    Guru 34333 points

    If difference is only in power consumption (and I prefer lower) than I can use (more avaiable) LS part.

    LVC2G07 is perfect, but output signal is going over the cable, and I am afraid about over/under shooting due to fast switching, and interference with other signal wires in cable. But if output at IC pin is pulled to 5V over 1k, than over/under shooting is dumped?

  • 0 in reply to zrno soli
    Guru 271290 points

    The speed of rising edges is determined only by the pull-up resistor. (So they are slow.)

    The speed of falling edges is determined by the drive strength. The SN7406 and SN74LVC1G07 are actually quite similar. You need only 5 mA, not the rated 40 mA/32 mA, so you could add a series resistor (it would form a voltage divider with the pullup, so it should be smaller than 100 Ω).