1. Home
  2. Electronics Design
  3. Deja-vu redesign task

Deja-vu redesign task

I am likely to be tasked with "recreating" a board/design from the mid-70's which (among other considerations) used some long-obsolete Fairchild 9000 series chips. At the time, these were chosen for their speed and functionality.

This board is part of a multi-board setup, and as such retaining the original "block diagram functionality" is essential.

95H28 - Dual D flipflop that happily clocked at 250 MHz when configured as two cascaded /2 stages. Anything dual-D - preferably DIP - that goes that fast and is readily available would suffice.

9504 - a quad triple-input OR gate in a DIP-16, with one input per gate commoned as an enable. Followed the above, max Fin was 70 MHz in the application. As all pins are employed in the existing design, finding a single-chip replacement block is proving a challenge.

Also used the Motorola MC10216 which I can't find "out there". (The application ran faster than the 10116). The role is a limiting amp with inputs to 250 MHz.

There was also an 11C90 or 95H90 as a high-speed (for the day) /10 prescaler stage. The biquinary nature of the division was not a requirement. While I have seen a lot of DIP-8 and SMD prescalers, they seem to all be either powers of 2 or dual modulus for synthesisers, and again /10 is not apparent.

I would welcome suggestions for functional replacements. If responses are along the usual lines of "use a PIC", "start with a fresh slate" or "give up" the please don't waste my time and yours.

Reply to
pedro
Loading thread data ...

Re-do the functionality with ECLinPS and translate back to TTL at the periphery. ECLinPS only comes in surface mount packages, and these take up a lot less board space than through-the-board TTL. The ECLinPS

100E116 is probably quite a bit faster than the MC10216 - the 216 line- driver/line receiver was was a bit faster than the 116, but ECLinPs was about a factor of four faster than the 10k ECL series.

ECLinPS has perfectly fine multipurpose counter, which goes to 550MHz

formatting link

Similar - if rather more specialised - EL and EP parts are faster, but there's no EL or EP 136

formatting link

Or do everything in a single big, fast programmable logic device - which will run at a lower supply voltage - and deal with the voltage compatibility with buffers. The speeds mentioned are easily attainable inside today's programmable logic.

This may strike you as "starting with a fresh slate" but you should be able to reproduce the functionality without much intellectual effort, and with very high confidence that what you put together can be plugged into the original system and will "just work".

There is the risk that the modern parts will react to glitches that the older hardware ignored, but a little judicious filtering on the inputs would fix that - you might not even have to load the filter components but it would be wise to add pads to accommodate them if it turned out that you needed them.

--
Bill Sloman, Nijmegen
Reply to
Bill Sloman

FPGA.

Reply to
krw

You could do the whole thing with a couple-of-dollars CPLD, with possibly some level translation. You'd have to program it, but the tools would be free. Modern CPLDs are planty fast enough.

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom timing and laser controllers 
Photonics and fiberoptic TTL data links 
VME  analog, thermocouple, LVDT, synchro, tachometer 
Multichannel arbitrary waveform generators
Reply to
John Larkin

LDVT receivers -- John Larkin uses them as super fast comparators.

The CPLD probably really is the cleanest way, but, if strict replacement is the goal, searching DigiKey for "ecl" and "in stock" gives a plethora of choices. 10E, 10EP, 10EL, 100EL, etc.

For example,

formatting link

single D-flop, 2.8Ghz f(toggle), t(prop) < 620pS.

--
Cheers, 
James Arthur
Reply to
dagmargoodboat

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.