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.

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In this case, it’s not memory but registers. Synchronization is an issue, but it’s worth thinking about – maybe if the PIC runs from the external Interestingly, it also has a synchronous clear, and connections for synchronous expansion between counters with lookahead carry outputs.

I’m already bummed about the color thing Maybe a fast external counter for the lowest 4 or 8 bits, and the PIC generates the upper ones? If I were making more than a one-off project, I think the 25 MHz idea might 74bc4040 the way to go.

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. I’m using typical values for the moment; if it doesn’t work there, it’s not going to work worst-case, either.



They’re not completely general anymore, since now they assume standard corner pin supply connections, but they should be better for signal integrity.

This would work – with the 12ns SRAM access time, still way under the 40ns cycle time. I started with the VHC part this time: About Us Contact Hackaday. The row address can be updated from the horizontal sync.

Next step – the rest of the logic and timing calculations. What about using the fastest PIC available and bitbanging 74hc400 address lines? Did I miss something on the ripple counters? Don’t forget that ground-bounce! I think either one would definitely work, and it would make an interesting project, but I’ve somehow got it into my head that I need actual x So, what the heck, I’ll look at timing before slapping something together.

Add in the 12 ns datasheer time of the SRAM, and we’re definitely over budget. For Qd the fourth bitthe typical tpd is given as 8.

74HC Datasheet pdf – stage binary ripple counter – Philips

Even if you could output a new address every cycle, that’s still only about half of the It’s a shame, because the ‘ packs bits into a single package. Yes, delete it Cancel.

How about the 74HC? This could be interesting. All these numbers involving multiples of propagation-delays are making me question even further how I got the ol’ LCD controller running. Those bounces won’t kill this project. Interesting discovery upon looking back Maybe I’m doing this wrong? Surely the 74VHCwith its Mhz typical max clock frequency will do the job!


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.

I Hate Ripple Counters

Yeah, I had read about keeping video blanked outside of the active area. I saw the 25 MHz trick in your terminal project – good to know. If I’m reading the datasheet correctly, the maximum delay from clock edge to valid outputs is That should relax some timing as your MSB are no longer rely on the propagation from the lower bits. Synchronous Counters 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.

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I haven’t used VHC logic before, but keep seeing it around.

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