Okay, I have some 74HC595N shift registers, but I guess those won't work as they have no internal transistor/mosfet to switch the load. If I should use these, I would have to use external transistors/mosfets.
I thought most TTL ICs are capable of handling 50mA current (sink or source) per output pin?if you just need 22mA, 74595 should be fine.
Quote from: Palatis on Mar 09, 2014, 08:33 pmI thought most TTL ICs are capable of handling 50mA current (sink or source) per output pin?if you just need 22mA, 74595 should be fine.You clearly thought wrong then!Take a look at the basic 7400 datasheet. Note the specifications for low drive as sixteen milliamps, and drive high as 400 microamps. Short circuit current possibly as high as 55 mA for one output only.
Does this mean that it's safe for me to use my 74HC595N shift registers to drive my Numitrons? or should I use the TPIC6B595N's I've ordered? - everything seems to run just fine using the 74HC595N's