[time-nuts] Linear voltage regulator hints...

Arnold Tibus arnold.tibus at gmx.de
Mon Dec 8 19:49:30 EST 2014


Am 08.12.2014 um 19:18 schrieb Dan Kemppainen:
> Hi,
>
> In playing with some oscillators and a GPSDO here, I think I'm seeing
> a voltage sensitivity issue.
>
> So, I started looking at the output voltage of various regulators vs.
> temp. Using standard LM/UA type linear regulators and some LDO's, they
> all appear to be pretty sensitive to temperature. (millivolt / few
> degrees Fahrenheit sort of sensitivity). Most of the datasheets seem
> to ignore temp sensitivity. Almost like they are so bad they don't
> want to publish it...
>
> Does anyone have hints on TO-220 or D-Pak type regulators that have
> really good temp coefficients and good line regulation? A few PPM/Deg
> C might be nice, if possible. Or am I into a 'roll you own' type
> design...
>
> Dan
>
Hi Dan,

I like to use the universal LM723C or µA723C, manuf. eg. Ti or NS
Short description:
it contains a temperature compensated reference source Vref Zener, ext.
filter C is connectable to further reduce noise
abt. 150 ppm/°K offset drift, but possible to work with ext. ref. as eg.
LM129, 1n82x, LM399 etc.
still available in N (DIL14), J, U, FK packages
The LM723 can produce up to 150mA of output current without additional
transistors
hp did use it quite often in their equipment.
Lot of example circuits and hints can be found in the internet
to avoid unwanted oscillations use ceramic Cs as close as possible
connected to the circuit.

Good luck,

Arnold, DK2WT



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