HCT/TTL output current and supply current

TTL is a current sinking family. Outputs sink current from an external source.

"Grant Stockly"

** Says " Per Output Pin ".

So 140mA is possible with all four outputs in use.

** Cos something in the common Vcc & Ignd lines will not tolerate 140 mA indefinitely. ** 140mA at 7 volts = 980mW.

The max dissipation figure ( 750mW) is * theoretically * well possible under overload conditions - assuming the full 7 volts is dropped across the conducting MOSFETS.

...... Phil

You use some care in your design so that the total dissipation is less than 750 mW, like don't load them to the limit. A TTL input shouldn't need more than a few mA to get pulled high (although, I'd use a series resistor to limit _base_ current), and when pulled low, it only draws leakage, which will^H^H^H^Hshould be negligible. :-)

If you're trying to use them for power drivers, then, as I said, use care in your design, or use ULN2003 or so power buffers.

Hope This Helps! Rich

Thanks for the advice that everyone has given me. I am trying to choose a modern part to replace some bus drivers on a new S-100 card design. I'm trying to find a suitable replacement for the 8T97/74367 and a new implementation using the '125 parts. I can get old parts but they are not as reliable as the new ones it seems.

The HCT parts look like they can drive enough TTL loads to be a good match for the project. I don't expect that any of the pins will see any huge amount of current except for one, but that won't happen very long or very frequently.

Grant