Why is a 15 stage binary counter/divider so cumbersome?

Question

There seem to be many ways to take a 32.768kHz signal and turn it into 1Hz.

• I can use a CD4060, but still have to add a flip-flop... so 2 "large" chips with excess (potentially) unused functions there. Sure the other 4060 outputs could come in handy, and I might find a use for the other flip-flop on board, but still a lot of real estate for a pile of maybe with a built-in oscillator likely as accurate as a 555 - negated by a crystal anyhow.

• The "Swiss Army Knife of dividers" - I can use the programmable CD4536, which provides a single output from any stage from 1-24. But again, with chip size and "wiring" for programming - a lot of real estate for one function - and again with the on board oscillator.

• The picture of simplicity, Nexperia makes a small 5-pin 14-stage divider. Oh so close. Still need to add a flip-flop, but at least the '4214 is not a 16 lead divider like the '4060.

• Just for fun, I could cascade 8 CD4013s.

There are other counter/dividers that fall very short or way beyond 15 stages as an option. It seems that 15 stages of binary division is not nearly as important as I would suspect.

So my question is: With the 32.768 kHz Crystal being so prolific, and the (I would think, common) need to yield "seconds" with clocks and timers, why is there no discrete solution for doing so? Am I missing something?

P.S. I know that microcontrollers, GPS RX, RTCs, and other modern devices can provide all the timekeeping function one might need, but with all of the other "archaic" technology still available, I find it hard to believe such a device doesn't/didn't exist.

Addendum I seem to have created some confusion with my example, where I was personally looking for a 1Hz signal from what I thought was a "jellybean" frequency. But, it's about the stage count availability, not the frequency yielded. My example is my discovery of a lack of devices with a specific intermediate division capability - regardless of the input frequency - where the output of \$2^{15}\$ (and 16th and 17th) seems to be almost avoided, and that with the exception of one example, an additional device is required to achieve that number.

I already had my 1Hz solution before this question, but got curious and sought out what I thought was the "old way" of achieving this frequency in small, cheap timing products. So, my search was for a 15th stage readily available within a single device. Maybe the 32.768k wasn't part of the old way at all. Regardless, it seemed odd that all of the available preset counters/dividers I found that provide select ranges between \$2^0\$ and \$2^{24}\$ seemed to beat around that \$2^{15}\$ bush.

Answer 1

The reason is that that's not all a counter needs to do.

Since any timer or counter will need to provide BCD counters for the seconds (and minutes and hours, if appropriate), along with display formatting and driving, it makes far more sense for the custom IC to incorporate both the oscillator and the divider chain into the IC, rather than having this as a second, external IC.

What you seem to be asking is why nobody makes a 6-pin IC which takes power, ground, 2 pins for the crystal, and outputs a 1 Hz signal. Well, that's because there isn't much demand for it.

If you want 1 Hz, a much smaller solution is this ASTMK part, which provides 1 Hz logic-level output in a 2 mm x 1 mm package, which is smaller than a standard 32,768 crystal, which typically will run about 4 mm x 8 mm.

Answer 2

with the 32.768 kHz Crystal being so prolific, and the (I would think, common) need to yield "seconds" with clocks and timers, why is there no discrete solution for doing so?

Is that need really all that common? aside from consumer analog wall clocks, which tend to use cheaper things than DIP packaged ICs, I see none right now – anything that does more than move a seconds hand will simply have a minimal MCU (microwave oven), usually, or even some ASIC (watches, for example).

The use cases for something that only divides a slow clock by \$2^{16}\$ kind of seem sparse.

Answer 3

I also needed a 1 Hz clock and wanted to avoid the usual CD4060 / CD4013 / CD4521, and I just found this AHC divider series from NXP, in particular the 74AHC1G4215 that does just that, has a small package and is available for 50ct in qty. 1 from Digikey for example.

I think these are quite recent and weren't available when you posted your original question. For the moment they seem little known, maybe in the future we'll see more of them in DIY clock builds!