In my opinion the best way is still to use two 74xx90 connected divide by five and divide by two. That gives a symmetrical output. That is why you can not use a 390. The A output should subsequently be applied to a D or JK flip flop with the clock input connected to the 10 MHz. The D or JK F/F should be as fast as what is presently still available. Bert Kehren Miami WB5MZJ In a message dated 3/30/2009 1:10:57 A.M. Eastern Daylight Time, [email protected] writes:
> What would be a "through the hole" type of IC that would have less > jitter than a 74xx90. I CAN do surface mount if I have to. In general, I think faster logic families have lower jitter. I'm not sure I could prove that or find a good paper. There may be counter-examples. If you want low jittter, I think the right approach is to divide by X/2 and then do the final divide by 2 in a separate chip. There are several logic families that have only one gate or one FF in a package. They are usually SMT, typically SP-23 type packages with fairly big pins so hand soldering with old-fart eyes is not that hard. Prop time with multiple outputs in a package depends on how many outputs are switching. In the case of a divide by 10, the pattern is stable. If you look at the divide by 2 output pin, I'd expect more jitter since sometimes lower order bits are switching and sometimes they are not. Another approach is to use a CPLD. Clock the main divide by 10 or 100 on the wrong edge, and then buffer the final output on the right edge. Some CPLDs are targeted at low power. It'd expect them to have more jitter than the ones targeted at high-speed. There may not be much choice. -- These are my opinions, not necessarily my employer's. I hate spam. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. **************Worried about job security? Check out the 5 safest jobs in a recession. (http://jobs.aol.com/gallery/growing-job-industries?ncid=emlcntuscare00000003) _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
