Part Number: 74LS, Maunfacturer: Motorola, Part Family: 74, File type: PDF, Document: Datasheet – semiconductor. These 8-bit shift registers feature gated serial inputs and an asynchronous clear. A low logic level at either input inhibits entry of the new data, and resets the first. This 8-bit shift register features gated serial inputs and an asynchronous reset. The gated serial inputs (A and B) permit complete control over incoming data as a.

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IF the pin is NOT being used for any function, ie: Setup Time, A1 or A2 to Clock.

74LS164 Datasheet PDF

Maximum Ratings are those values beyond which damage to the device may occur. The gated serial inputs A and B permit complete control over incoming data as a low at either or both input s inhibits entry of the new data and resets the first flip flop to the low level at the next clock pulse.

Propagation Delay Time, Clock to Q. I have this lingering gut-feeling that I there is something very basic that i am not understanding You do not require pull downs. If I understood the datasheet’s diagram correctly, there’s an AND gate on the two input pins, so I think both have to be high – but that doesn’t really matter, since I simply connected the two together. Low Level Output Current. High Level Output Current. Output Short Circuit Current.

Read the above entry d it seems that the LS type ICs are famous for their floating voltages and sensitivity – is there some other type of IC that might be more forgiving for a beginner?

Or am i maybe measuring the voltage in a wrong way? Propagation Delay Time, Clock to Q. That didn’t nudge the 1.


I’m a software guy, who is now trying to get a little bit into circuits, just for fun. Thread starter schweini Start date Nov 16, Could I simply buy a handful of the same ones, or does the difference actually make a huge difference, somehow? Your circuit may work Datahseet sometimes and then not others, for a reliable, predictable circuit follow good engineering practice.

74LS Datasheet(PDF) – Fairchild Semiconductor

Low Level Input Current. Thank you very much for that diagram – although I think I have none of the components you added at hand and I hope they sell them here! Same with ‘cleaning’ capacitators. Propagation Delay Time, Reset to Q. If I have a shared clock signal for both the ICs which dayasheet to be a common pratice datsheet, then this high input on the second ICs input would get shifted 8 times, until the first IC has any way of affecting that pin – so all outputs of the second IC would be high by then.

All diodes are 1N or 1N All diodes are 1N or 1N Low Level Input Voltage.

74LS164 8-bit Shift Register IC

Since the IC is a relatively bad datasjeet right? Just one last question i hope: But I’d be happy to stand corrected. You do not need a pull down resistor.

I’m simply poking my multimeter at the pin and the common ground Is that a good thing, or a bad thing? Functional operation should be restricted to the Recommended Operating Conditions.

Where this voltage is datasheeh from, I don’t know.

High Level Output Voltage. My problem is that nothing seems to work, and, even worse: For anybody else with the idea of going the pull-DOWN route, i found this article that finally convinced me of my erroneous ways, which i’d like to share: I googled around, and most of the internet seems to agree that a pull-up and datasheer resistors are nice and all, but shouldn’t really be an absolute necessity for a simple thing like this and, I don’t quite ‘grok’ them b I was afraid that I somehow fried my ICs, but noone else seems to have a problem connecting them directly to their power supply.


Thanks, and sorry that this post got rather lengthy.

If you just ‘hook things up’ as the ‘so call experts’ state you will get the problems that you are experiencing. In my so-called diagram, I drew 74,s164 I would have thought to be a pull-up resistor on the signal pins in red.

74LS Datasheet(PDF) – System Logic Semiconductor

Satasheet high level input enables the other input which will then determine the state of the first flip-flop. Search field Part name Part description. This works even with a tiny wire, so I hope that capacitance is not the issue. There could be any number of reasons why its not working, follow my instructions and we may find out why. The mains electricity here in Costa Rica is horrendously ‘dirty’, so I wanted to eliminate that factor.

Replacing a 4 pin leaded inductor with a 2 pin Started by gkmaia Yesterday at I think I understand the function of the capacitators de-noising, by functioning as a little ‘buffer’ of sorts, right?

This seems to contradict any basic understanding of physics I thought I had. Diver Well-Known Member Nov 16, If own of the two posts gets an answer, I will of course also post it on the other board. That switch dataeheet NOT turn on the outputs – but touching that pin does.