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

[Bob kb8tq]

Hi

Part of the problem is radiated / mag coupled spur energy. One of the things that 
makes the fancier switchers more friendly is that they can contain this better. 

Bob

> On Mar 10, 2019, at 12:10 PM, jimlux <jimlux at earthlink.net> wrote:
> 
> 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
> 
> 
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