[time-nuts] Anybody want a Thunderbolt power supply
tractorb at ihug.co.nz
Thu Sep 1 00:09:45 EDT 2016
Getting the required Thunderbolt supply rails from a nominal 12v dc supply
of doubtful cleanliness is an issue that also needs to be addressed. I'm
still mulling over that one. (and using a triple output switcher from an
inverter backed mains supply meantime!)
The ex-telco GPSDOs all run on a nominal 24-50 volt DC supply but I don't
know how they generate their internal supplies. I suspect switchers?
----- Original Message -----
From: "Charles Steinmetz" <csteinmetz at yandex.com>
To: <time-nuts at febo.com>
Sent: Thursday, September 01, 2016 3:35 PM
Subject: Re: [time-nuts] Anybody want a Thunderbolt power supply
> Bruce wrote:
>> Low noise regulators for the +12V and +5V outputs would also be useful.
> Very true. By focusing on the -12v supply, I did not intend to suggest
> that low noise is unimportant on the +12v and +5v supplies.
> The suggestion to use LT3042s is a good one, but note that it has an
> output current rating of 200mA. The Tbolt needs ~250mA at +5v, and ~700mA
> at +12v [at startup -- but only ~150mA steady-state, depending on ambient
> temperature]. LT3042s can be used in parallel, so two of them for the +5v
> supply and four of them for the +12v supply would be required. That isn't
> so bad for the +5v supply, but seems excessive for the +12v supply
> (particularly when three of the four are needed only during warmup from
> The LT3088 and LT3080 will deliver 800mA and 1.1A, respectively, with low
> noise (but not as low as the LT3042). One of those might be a better
> choice for the +12v supply. Similarly, the LT3085 can deliver 500mA, so
> one of those could be used for the +5v supply.
> Finally: Linear Technology -- Where is our negative-voltage complement to
> the LT3042?
> Best regards,
> time-nuts mailing list -- time-nuts at febo.com
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