[time-nuts] ULN regulator with more current capability than LT3042?

[Bruce Griffiths]

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 <jra at 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
> > 
> > 
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