John, The specifications for AC coupled input sensitivity of the 74HC4046 from the major manufacturers are shown below. Brooks found that the Fairchild device had lower sensitivity and recommended using devices from TI or Phillips.
Fairchild MM74HC4046 Ac coupled input sensitivity @ 500 KHz 25mv p-p typical, 100mv p-p guaranteed at 25C @ 2v 50mv p-p typical, 150mv p-p guaranteed at 25C @ 4.5v 135mv p-p typical, 250mv p-p guaranteed at 25C @ 6v Phillips 74HC4046A, TI CD74HC4046 Ac coupled input sensitivity @ 1 MHz 9mv p-p typical @ 2v 11mv p-p typical @ 3v 15mv p-p typical @ 4.5v 33mv p-p typical @ 6v On Semiconductor MC74HC4046A Ac coupled input sensitivity not specified Richard > Ulrich Bangert said the following on 04/04/2009 06:13 AM: > >>> As a curiosity, there are various variants of the original 4046 which >>> has different sensitivity on the input side... one of them >>> has several inverters in a row to get the needed gain where as the other >> variant >>> does not. This difference made a huge difference in some applications. >> >> are you going to say with that it would be reasonable to test different >> brands for input sensivity? I have been believing that all brands have this >> inverter chain. > > Brooks Shera used the 4046 as the input conditioning circuit in his > GPSDO that was published quite a while ago. I seem to recall that he > noted only certain brands seemed to work well, but I don't recall the > details. > > John > > _______________________________________________ > 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. > _______________________________________________ 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.
