Texas Instruments 74LS Logic Comparators are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for Texas Instruments . December INTEGRATED CIRCUITS. 74HC/HCT 8-bit magnitude comparator. For a complete data sheet, please also download. Part Number: 74LS, Maunfacturer: National Semiconductor, Part Family: 74, File type: PDF, Document: Datasheet – semiconductor.

Author: Vujind Nikojar
Country: Nepal
Language: English (Spanish)
Genre: Life
Published (Last): 23 August 2008
Pages: 337
PDF File Size: 20.41 Mb
ePub File Size: 8.73 Mb
ISBN: 181-1-40419-783-2
Downloads: 34498
Price: Free* [*Free Regsitration Required]
Uploader: Bralmaran

My calculations say yes, with lots of time to spare, but I’d like others’ opinions.

In other words, what function does it serve? It’s an 8-bit comparator, but it’s cheaper than the 74LS85 and has an enable input. A way to avoid that would be to de-glitch the circuit by adding a synchronizing flip-flop running 74ls88 16MHz just before the latching flip-flop. This sets the D-type flip flop, which switches off the NOP generator and turns on the bus tranceivers.

74LS datasheet & applicatoin notes – Datasheet Archive

As the address datssheet transition and settle out, they might very well set up a glitch that agrees with the test condition, well before you intended. I’m currently designing the power-on-jump circuit for my processor board. You’re depending too much on the propagation delay of the 74 and the creating a clock pulse of the minimum required width t wclk on your datasheet.


There may be better ways to do this job so keep tinkering. Just to scratch my own curious itch, what does the connect to?

It is a glitchy signal. Here’s the pieces relevant to Power on Jump: This might cause a false trigger if your address trap was at B. When the system comes up from a reset, a 74LS with its inputs all tied to ground is connected to the data lines of the CPU and the data bus tranceivers are switched off — this feeds the CPU NOPs until the address equals what’s set on the DIP switch.

Comparator 74LS688 DIP20

I’ve never had to use one. If you expect to use it, you need to turn the enable off during the time when the compare inputs are in transition. It’s comparing the high four address bits to a 4-position DIP switch.

This is all fine. Glitchy output shouldn’t be a problem — glitch, I see how you got your nickname. Note datqsheet this would take away 62 nS from the access time of the first instruction fetch after the proper address compare, but it should be OK if you are using newer memory devices. I got lost reading that.

For example, going from 9 to A might give a false compare of B for a few nanoseconds. You can’t use it while the inputs are changing. I’m not talking about little tiny noise spikes.


SN54/74LS datasheet & applicatoin notes – Datasheet Archive

Hi No it won’t. It might work, but I don’t like it much.

Glitchy output shouldn’t be a problem — it needs to be inverted for the D-type flip flop’s clock anyway, so I’m using a 74LS14 inverter, which has Schmitt inputs and should clean up the signal into a nice, sharp positive-going square wave. This would also add about 62 nS to your latch clock which right xatasheet is only 3 gate delays long and would be difficult to see on an old low bandwidth scope.

I don’t do well with word descriptions of circuits–can you draw a schematic?

74LS688 Datasheet

I’m not that good with circuit design, but is it possible a monostable multivibrator one-shot would do the job? Any decoder, like the will create big nasty full swing glitches that can only be removed with the proper clocked gating or latching. It may even make it datzsheet. Hi I doubt you’ll be able to run the output of the directly to a clock. You could then use it as a clock.