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| Need help with an alternate part! |
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| samsmock:
I've got PCB's that I've built for years. Parts went obsolete on them years ago. I bought a bunch from Hong Kong and have had enough to keep me going for quite a while. Now I'm looking again. One of the suppliers pointed me to a possible substitute for the flip flop I've been using. I've never come across it before, and would like to get someone elses opinion of whether or not it's a match. Things look like they'd work to me, but I want to make sure I'm not missing something. So the part I've been using is here. http://pdf1.alldatasheet.com/datasheet-pdf/view/53719/FAIRCHILD/MM74C74.html The alternate they are suggesting is here. http://www.alldatasheet.com/datasheet-pdf/pdf/15662/PHILIPS/74HC74D.html Can someone double check me on this? |
| tsman:
There are several differences between those two parts. Things like the timings + propagation delays are completely different. The supply voltage range is far bigger on your old MM74C74. Only you can tell if it is compatible by looking at the rest of your circuit. |
| Benta:
If your circuit is running a 5 V supply, the 74HC74 is a drop-in replacement, although the faster signal edges/delays may cause issues. If your circuit is operating at higher voltages, eg, 12 V, the functional replacement is the MC14013/CD4013, which will require a PCB layout change or an adapter board. |
| samsmock:
Yeah, it's running at 5v. I may order some samples. Unfortunately, I do the assembly part and am out of touch with the guy who designed it for me in 2007! |
| t1d:
Don't forget about checking directly with the OEM for what they suggest as a sub. They have technical assistance, just for this purpose. And, the big component distributors also have personnel to help you with this very type of issue. Mouser, Digikey, etc. In doing your research, if you discover a new method to track down parts, please post it here. |
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