[time-nuts] Power supply for OCXO using "USB power blocks"

[jimlux]

On 3/10/19 8:58 AM, Richard (Rick) Karlquist wrote:
> Check out the LT3045-1. 
Ive used the LT3042 in a space application, it is basically the same 
thing with lower output current.  The really great thing is that the 
rejection extends up to 10 MHz.



  It is an ultra low noise (2nv) linear
> regulator with very high PSRR that has a 1 MHz bandwidth.
> The -1 version can control an external switcher (or linear)
> regulator ahead of it, where the voltage drop across the
> LT3045-1 can be set to, say 1V, and the front end supply
> output voltage automatically is 1V above the LT3045-1
> output voltage. 

I didn't know about the -1 version.. I'll have to take a look.



  It has 120 dB PSRR at 120 Hz.  You
> can buy an eval board for it.  Multiple LT3045's can be
> paralleled for additional current handling.  If the switcher
> is of the isolated type, you have galvanic isolation for
> the ultimate OCXO performance.
> 
> I think the vendor really got this right.

Yes, indeed


So my notional "run noise sensitive electronics from ubiquitous 5V USB" 
is "5V to TBD V boost converter (in a module from someone like Cui, most 
likely)" followed by a LT304X.

I will have to look into the "LT3045-1 feeds back a control signal"..

And as Bob notes - layout is critical (isn't it always) - but I must 
confess, the first one's going to be haywired with double stick foam 
tape for mounting.



> 
> Rick N6RK