I have a quad LT3042 board somewhere. I should get around to measuring its output noise.
Bruce > On 20 March 2018 at 03:11 John Ackermann N8UR <j...@febo.com> wrote: > > > Thanks, all. I think I'll end up using the 3042 with pass transistor, > partly for reasons of cost. I have no idea whether paralleling two > 3042s would result in lower noise from the device, and there are already > three or four fairly pricey chips on the board. > > I appreciate all the info! > > John > ---- > > On 03/18/2018 06:43 PM, Charles Steinmetz wrote: > > Tom wrote: > > > >> Run two in parallel for twice the current and less noise? > > > > This is actually a better solution than using an LT3045, for two > > reasons. First, as Tom noted, by paralleling two devices, the noise is > > reduced by sqrt 2 = ~1.4: > > > > "Designed as a precision current reference followed by a high > > performance voltage buffer, the LT3042 is easily paralleled to increase > > output current, spread heat on the PCB and further reduce noise -- > > output noise decreases by the square-root of the number of devices in > > parallel." [LT Journal of Analog Innovation, v25 n1 Apr 2015]. > > <http://www.linear.com/docs/46398> > > > > Second, it reduces the dissipation of each regulator, so they run > > cooler. And as LT says, it allows spreading the heat on the board (but > > it is not advisable to put them too far apart). > > > > The primary disadvantage is that two 3042s cost about half again more > > than one 3045. Also, board space may be a factor in some applications. > > > > So, unless you are extremely tight on board space or the ~1.5x cost > > increase is prohibitive, two 3042s in parallel are a better solution > > than one 3045 if you are seeking the lowest noise possible. > > > > Best regards, > > > > Charles > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.