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

[Bruce Griffiths]

The details are on the LT3042 datasheet.

A small series ballast resistor is used in series with each output and the Iref terminals are connected in parallel so only the offset of the unity gain output buffer is of significance.

Bruce

> 
>     On 20 March 2018 at 02:23 Peter Vince <petervince1952 at gmail.com> wrote:
> 
>     Please forgive this naive question, but I am concerned about the idea of
>     simply running two regulators in parallel. Just like you don't put two
>     batteries in parallel, how do you ensure accurate load balancing between
>     the two? I would worry that one of them, with a fractionally higher
>     voltage, would be driven into saturation, thus ruining any noise
>     isolation. I must be missing something here?
> 
>     Peter
> 
>     On 18 March 2018 at 22:43, Charles Steinmetz <csteinmetz at yandex.com> 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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