74HC Datasheet, 74HC stage Binary Counter Datasheet, buy 74HC, 74HC pdf, ic 74HC description/ordering information. The ‘HC devices are stage asynchronous binary counters, with the outputs of all stages available externally. A high. Data sheet acquired from Harris Semiconductor. SCHSD. Features. • Fully Static Operation. • Buffered Inputs. • Common Reset. • Negative.

Author: Tuzil Muzilkree
Country: Uruguay
Language: English (Spanish)
Genre: Personal Growth
Published (Last): 1 March 2015
Pages: 297
PDF File Size: 19.57 Mb
ePub File Size: 6.94 Mb
ISBN: 523-5-52475-177-9
Downloads: 82294
Price: Free* [*Free Regsitration Required]
Uploader: Fenrikora

How about the 74HC? Maybe a fast external counter for the lowest 4 or 8 bits, and the PIC generates the upper ones?

74HC Datasheet(PDF) – NXP Semiconductors

That should relax some timing as your MSB are no longer rely on the propagation from the lower bits. I’m already bummed about the color thing This could be interesting. If I were going to build a bunch of these, I’d try harder to get the 74HC to work. Doesn’t look promising – although the typical 21ns 6V or 25ns 4.

For Qd the fourth bitthe typical tpd is given as 8.

I Hate Ripple Counters | Details |

About Us Contact Hackaday. I started with the VHC part this time: If I were making more than a one-off project, I think the 25 MHz idea might be the way to go. Add in the 12 ns access time of the SRAM, and we’re definitely over budget. I have a tube datashdet 50 MHz cans around here that I could divide down, but since I have to order parts for this thing anyway, I might as well pick up the exact frequency for a few bucks.

So, what the heck, I’ll look at timing before slapping something together. Musta been a bunch of pixie-dust in there, or a poor memory of 18 years ago. I’m using typical values for the moment; if it doesn’t work there, it’s not going to work worst-case, either.


Synchronous Counters Synchronous counters use extra logic to form the next state from the previous one directly, without waiting for clocks to datwsheet through, so the outputs settle faster. Synchronization is an issue, but it’s worth thinking about – maybe if the PIC runs from the external Next step – the rest of the logic and timing calculations. This would work – with the 12ns SRAM access time, still way under the 40ns cycle time.

Did I miss something on the ripple counters? Even if you could output a new address every cycle, that’s still only about half of the Interestingly, it also has a synchronous clear, and connections for synchronous expansion between counters with lookahead carry outputs.

Since it’s a ripple counter, Q0 flips, then Q1, then Q2, etc, so we have to add all the delays so see how long it takes for the address to settle to the next value.

Yes, delete it Cancel.

74HC4040 Datasheet PDF

VHC to the rescue? I’ll have to give that one some thought. They’re not completely general anymore, since now they assume standard corner pin supply connections, but they should be better for signal integrity. Those bounces won’t kill this project. Sign up Already a member? I need 5 of them, which sucks. The 74VHC is another candidate – it has twin 4-bit counters in a package, so three ICs would be necessary.

Surely the 74VHCwith its Mhz typical max clock frequency will do the job! Monitors can handle some clock frequency variations. Cycling back the hsync for a second counter is interesting. In the store-each-dot-period-as-a-byte plan, this is trivial – I have full and easy control of all the singals on on a per-dot basis.


Synchronous counters use extra logic to form the next state from the previous one directly, without waiting for clocks to ripple through, so the outputs settle faster. If I’m reading the datasheet correctly, the maximum delay from clock edge to valid outputs is Yeah, I had read about keeping video blanked outside of the active area. All these numbers involving multiples of propagation-delays are making me question even further how I got the ol’ LCD controller running.

Maybe I’m doing this wrong? Interesting discovery upon looking back I’m going to ignore those timing calculations for the moment next log because there’s an even bigger problem here – it takes too long for the address to settle.

Now, I need 5 ICs to make the counter – if it’s even fast enough.

It’s a shame, because the ‘ packs bits into a single package. I saw the 25 MHz trick in your terminal project – good to know. In this case, it’s not memory but registers. Here’s a simplified schematic of the guts of the VGA framebuffer it ignores the reset and connections between the two ”s required to generate 19 bits of address.

In the schematic above, the ‘ counters increment the address on the rising edge of the clock, while the ‘ d-flop captures the data from the last address before it changes. I can hook one to the four-channel scope and have a look at the delays between the LSB and successive bits.

I think either one would definitely work, and it would make an interesting project, but I’ve somehow got it into my head 74hc40400 I need actual x