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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I saw the 25 MHz trick in your terminal project – good to know.

74HC Datasheet pdf – stage binary ripple counter – Philips

Interesting discovery upon looking back I haven’t used VHC logic before, but keep seeing it around. I’m already bummed about the color thing I’m using typical values for the moment; if it doesn’t work there, it’s not going to work worst-case, either. Doesn’t look promising – although the typical 21ns 6V or 25ns 4.

This could be interesting. That should relax some timing as your MSB are no longer rely on the propagation from the lower bits.

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

74HC4040 Datasheet PDF

Yeah, I had read about keeping video blanked outside of the active area. This also ignores the fact datasheef two 74HCs need to be chained to generate the bit address: What about using the fastest PIC available and bitbanging the address lines?


I can hook one to the four-channel scope and have a look at the delays between the LSB and successive bits. In the store-each-dot-period-as-a-byte 74hd4040, this is trivial – I have full and easy control of all the singals on on a per-dot basis.

I need 5 of them, which sucks.

74HC Datasheet(PDF) – NXP Semiconductors

I’ll have to give that one some thought. The dot clock is So, with two of them connected to generate 19 bits of address, the tpd from the clock edge to the MSB settling is: Musta been a bunch of pixie-dust in there, or a poor memory of 18 years ago. 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. 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.

74HC4040 Datasheet PDF

It’s a shame, because the ‘ packs bits into a single package. If I were going to build a bunch of these, I’d try harder to get the 74HC to work. satasheet

Maybe a fast external counter for the lowest 4 or 8 bits, and the PIC generates the upper ones? I have to go take them out of my shopping cart now: 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 spent the afternoon re-working my ugly SOIC adapter board designs to reduce the ground-connection impedance and add on-board bypass caps. Those bounces won’t kill this project. For Qd the fourth bitthe typical tpd is given as 8. Let’s run the numbers, using a 15pF load: Cycling back the hsync for a second counter is interesting.

Did I miss something on the ripple 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.

Interestingly, it also has a synchronous clear, and 74nc4040 for synchronous expansion between counters with lookahead carry outputs. If I’m reading the datasheet correctly, the maximum delay from clock edge to valid outputs is This would work – with the 12ns SRAM access time, still way under the 40ns cycle time.