The SN54 / 74LS74A dual edge-triggered flip-flop utilizes Schottky TTL cir- cuitry to produce high speed D-type flip-flops. Each flip-flop has individual clear and. This device contains two independent positive-edge-trig- gered D flip-flops with complementary outputs. The infor- mation on the D input is accepted by the. 74LS74A datasheet, 74LS74A circuit, 74LS74A data sheet: TI – DUAL D-TYPE POSITIVE-EDGE-TRIGGERED FLIP-FLOPS WITH PRESET AND CLEAR.
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Hopefully, I will be answering the questions one of these days!
Quite often, at least one of the suffixes refers to the package. Also, when you say inputs do you mean the number of flip flops or the actual inputs to the flip flop? You have to be careful when mixing families due to drive capabilities. Should we ignore datasgeet they don’t have the same number of pins? I am fairly new to the hobby, but am really enjoying learning. Also just order from U. It was frustration from knowing I have to place another order just for one chip!!!
Instead of waiting two weeks too, if I were you i’d just bite the bullet and order some of those particular chips. Same D type Flip Flops, 74ls74 without the extra features of a I don’t have a background in electronics, so it is all a learning experience. I am always impressed by the amount of knowledge that some of you all have! I prefer Digikey over Jameco as they have more parts, and the Priority Mail shipping is usually cheaper provided you don’t order anything to heavy.
I had ordered a bunch of odds and ends from Jameco, so I ordered the chips with that stuff, but man they kill you with shipping, and then it is slow to boot! The manufacturer sites are also good for getting specifics about what you want. Data sheets are also VERY helpful when replacing chips with one from a different family. This is where datasheets are VERY helpful.
I know that the 74 is a dual d-type flip flop, while the is a hex d-type flip flop with clear, and the is a quad d-type flip flop with clear. The suffixes are often manufacturer-specific, so you’d need to consult that manufacturer’s datasheet and hope it’s detailed.
The down side of Digikey is the site can be hard to navigate to find what you want, but once you get used to the parametric search it is actually pretty fast. I was a little worried about fakes, although eatasheet you said, on inexpensive chips, there isn’t much incentive. Wouldn’t the board just ignore the extra inputs?
Thanks for the help, everyone. A good book for reference is the TTL Datasheey. You don’t really need to worry much about fakes for the standard TTL families, in my opinion. Okay, I will answer the why first. It would be nice if there was even a guide somewhere as to what the suffixes on some of these chips mean I hate to wait another week or two for one chip.
I learned the hard way on some cheap TTL replacements from Mouser. C most often means ceramic but TI uses J; some others used D P most often means plastic but TI uses N Another bit of data sometimes coded in the suffix is the temperature range i.
Look datasheft the data sheets for the devices, compare pinouts, compare truth tables, etc. In 74lss74a cases, if the last numbers are not the same, then the IC is not plug-in compatible. In general, it’s fairly safe to ignore the suffix, as it’s usually not of any real consequence for arcade applications. Definitely a learning experience. I had also previously used Mouser for some stuff, but they have to have the worst search on any site I have ever seen!
It has a lot of great information.
Thanks for the reply! Of course, maybe there is, and I am just too dumb to find it, lol.
The datasheets are useful as far as packaging goes. Many times you can get 74ls74z small qty of common chips, shipped, for a buck or two. You have to be careful because the suffix denotes packaging and you don’t want to get a SIP or surface found when you want DIP.
When you start getting into TTL PROMs and older 8 bit CPUs, which are usually pretty expensive and have been discontinued for a fairly long time, then you need to verify what you are getting.
I actually did just that today, and ordered some from eBay. Lol, crap, I was thinking they had the same number of pins. I know from datasgeet on to just grab them from eBay with free shipping!
If it’s cheap though a quarter there’s no incentive for it to be faked and usually you should be alright. If it had a standardyou may not be able to replace it with a 74LS74 depending on how many 7ls74a there are to the output.
It is definitely frustrating at times, simply trying to digest all of this information. I have been trying to learn the datasheets on these things. Not all parts are the same.
It’s old however you can still find them on Amazon. I always use US sellers only, and found one with free shipping. Is there a reason I can’t sub daasheet of these two for the 74? Again, thanks for the information, everyone! Mouser is another good source as well.