Regulator Synchronization

Andrey Sviyazov andreysviyaz at
Wed Nov 25 11:33:26 UTC 2015

Hi Sylvain.

Sorry for so delayed reply, I've found that I've lost subscription for this
mailing list.

Well, actually DC/DC were synchronized (between each other) even in the
very first UmTRX version.
On the first versions I saw spurs from DC/DC ~500 kHz at the TxPLL noise
plot (few in case of non-sync) and some other surprises.
You can see issue #42 here:

Nowadays, we use DC/DC chip TPS54560, synchronized to 541 kHz signal
(26/48) from FPGA.
No surprises noticed anymore, but actually, we chose TPS54560 because of
better efficiency and higher input voltage.

Best regards,

Andrey Sviyazov

> ---------- Forwarded message ----------
> From: Sylvain Munaut <246tnt at>
> Date: Sun, Nov 8, 2015 at 11:12 PM
> Subject: Regulator Synchronization
> To: umtrx <umtrx at>
> Hi,
> I know that on the UmTRX the switching controllers ( ST L5973 ) are
> all synchronized together.
> IIRC the earlier versions of the UmTRX didn't have this and I'm
> wondering if you really noticed a difference due to this change ?
> Cheers,
>     Sylvain
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