From: "Poul-Henning Kamp" <[EMAIL PROTECTED]> Subject: Re: [time-nuts] Off the wall: anyone with experienceprogrammingHP3456A? Date: Sat, 10 Sep 2005 23:26:57 +0200 Message-ID: <[EMAIL PROTECTED]>
> In message <[EMAIL PROTECTED]>, Magnus Danielson writes: > > >> This is less of a problem with modern CMOS based interface chips. > > > >Actually, there you end up in another problem, you power the box through the > >protection diodes which you really must have for CMOS. So it is really not so > >much better, just different. > > This doesn't happen in any of the designs I've seen. They basically have > a FET in series with the line and when the instrument is OFF, it is really > OFF. OK, then they have done it properly. If you don't... OUCH! We learned the hard way when we did the first attempts on hotswap. Burned a perfectly nice FPGA input into a nice little low-impedance short-circuit which happilly ate several amps. :/ Cheers, Magnus _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
