That's a really nice part, like the old LM723 was bring your own pass element, the 3042 is essentially bring your own reference, I hope that is a trend that continues. And a 10uF capacitor is pretty quiet at 1KHz plus. The other neat thing about the 3042 is the error amplifier is run unity gain with a compensation network. For a typical 12V ldo you loose 20 dB loopgain and 1 decade of loop bandwidth gaining up 1.2 VRef to 12 V on the feedback divider. At 12 V I'm sure the 3042 would blow a typical LDO out of the water in line/load regulation. On Wed, Dec 7, 2016 at 11:36 PM, jimlux <jimlux@earthlink.net> wrote: > On 12/7/16 4:20 PM, Scott Stobbe wrote: > >> Yes, the short hand I like to use is 4 nV*sqrt(R/1000). >> >> 2 nV/rthz off a bandgap is pretty darn impressive, that includes a delta >> vbe gained up ~10x. >> >> On Wed, Dec 7, 2016 at 7:03 PM Bob Camp <kb8tq@n1k.org> wrote: >> >> H >>> >> > the cool thing about those parts is that their PSRR extends up to several > MHz. A lot of LDOs have good PSRR to kHz. > > Someone at LT did a good job on that design. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. >

On Thu, 8 Dec 2016 02:25:14 +0100, you wrote: >Am 08.12.2016 um 01:20 schrieb Scott Stobbe: >> Yes, the short hand I like to use is 4 nV*sqrt(R/1000). >> >> 2 nV/rthz off a bandgap is pretty darn impressive, that includes a delta >> vbe gained up ~10x. > >Methinks the advantage comes from converting their reference (whatever >that may be) >to a really high impedance current source where a few uF help >tremendously in cleaning things up. > >regards, Gerhard The output stage of the LT3042 also operates with unity gain so the reference noise is not multiplied by the gain set by the divider and bandwidth of the error amplifier is maximized. Some regulators include an extra pin or the voltage divider is external so that point can be bypassed but their reference is still in series with the error amplifier so this does not suppress noise from the bandgap reference itself.