[time-nuts] low power divide by 5

[jimlux]

On 7/2/20 2:50 PM, Bob kb8tq wrote:
> Hi
> 
>> On Jul 2, 2020, at 5:30 PM, jimlux <jimlux at earthlink.net> wrote:
>>
>> On 7/2/20 11:37 AM, ed breya wrote:
>>> It's been fun reminiscing about all these dividers and techniques, but getting back to the OP, the original search was for a divide by 5 with "low power" and operation from 5 to possibly 3.3V, and clocking properly at 50 MHz. One would assume also minimal size and complexity, and low cost.
>>
>> You forgot to add rad-hard.. I was the OP - This has been a fascinating thing - we have a breadboard that uses a fancy clock distribution chip that consumes close to a watt (and has too much jitter, as well)..
>
>> 3) It's hard to even find programmable logic that is simple and small. All the mfrs tout their latest tiny parts with *only half a million gates* (I exaggerate, but you get the picture)
> 
> If they want to sell you a fully self contained "million gate" device for a couple bucks, is that really
> a bad thing?  Sure, if it’s in a thousand pin BGA, it’s a bad thing. If it’s in a < 40 pin package that
> you can get on a small board …. maybe not so much.

yes, if it's in a small pinout package. One other peculiarity that I've 
been burned by is that a lot of the modern devices with large logic and 
few I/O pins have power dissipations that are clock rate independent 
for the internal logic - it's the leakage current that dominates and 
that's VERY dependent on die temp.


I think though, that the marketplace is driving towards increased 
functionality on one chip, with bigger die size. Those of us who want 50 
gates at medium or low speed are distinctly in the minority.