From: David Challis <dchallis@cox.net>
To: 'Microcontroller discussion list - Public.' <piclist@mit.edu>
Sender: "piclist-bounces@mit.edu" <piclist-bounces@mit.edu>
Date: Thu, 15 Jul 2021 23:07:38 -0700
Subject: RE: [EE] Redundant PSU for critical NAS server
Thread-Topic: [EE] Redundant PSU for critical NAS server
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Check out page 20 of the LTC4364.   It may be what you are looking for.

Dave Challis
(many years MIA from this list).

-----Original Message-----
From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> On Behalf Of smplx
Sent: Thursday, July 15, 2021 10:35 AM
To: Microcontroller discussion list - Public. <piclist@mit.edu>
Subject: Re: [EE] Redundant PSU for critical NAS server


Some time ago I came across a circuit for combining PSUs. It used something=
 called and ideal diode. I've had a ***quick*** look but can't find the cir=
cuit again but there is lots of stuff out there using ideal diodes. Perhaps=
 you could do a search and find something?

Regards
Sergio Masci

On Mon, 12 Jul 2021, foros@arocholl.com wrote:

> Hi there,
>
> Over the last couple of years have experienced problems with PSU=20
> failing and shutting down connected NAS servers, twice. These PSUs are=20
> 12v/100W external units from the manufacturer (Synology). The funniest=20
> thing is the PSUs are fully protected with 220v UPS but of course=20
> nothing helps if they fail themselves, and they do, without any=20
> advice... Not a good setup for a critical server.
>
> So I rather no longer rely on the manufacturer PSU and design my own,=20
> overrated 12v/200W redundant supply. My current thinking is to proceed=20
> like this:
>
> * Have two identical 12v PSU adjusted to different DC levels (12.6v=20
> and
> 12.2v) each one connected to a pair of schottky diodes (2x parallel=20
> 15V 9A 95SQ015 I have spare) so one PSU is the active one and the=20
> second PSU is running ready but passive.
> * In theory if the active PSU fails, the passive one becomes active=20
> and diodes prevent anything funny from happening.
>
> [Active PSU 12.6v]  -> 2x Parallel Diode -> Joint [Passive PSU 12.2v]=20
> -> 2x Parallel Diode -> Joint -> NAS server
>
> I've been testing this setup and the diodes get barely warm so=20
> everything looks kosher to move to production. I also tested the=20
> active/passive -> dead/active scenario with some alternative charge=20
> but don't want to risk the actual server with a full charge test.
>
> So I wanted to check if you have been there already and found a better=20
> setup, or if this approach may have an obvious issue I currently do not s=
ee.
>
>
> Regards,
> Ariel
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive=20
> View/change your membership options at=20
> http://mailman.mit.edu/mailman/listinfo/piclist


--=20
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