Power Supply Sequencing to V4 MGTs

Peter,

There is no sequence sensitivity that I am aware of.

Perhaps there is something introduced as the device configures, and starts or tries to calibrate MGTs before all the supplies are present?

Since the device requires one Vcco (for the config bank), Vccaux, and Vccint to be above their power on reset thresholds, the device could configure and start before the MGT supplies are present or even while they are still changing (depending on how fast they power on in relation to the other three supplies I mentioned).

That might be the source of your problem?

Aust> Does anyone know if it's a problem if the LDO supplies to V4 MGTs come

Fantastic. Thank you.

No problem *yet*, I'm still at design stage, just want to aim for the golden egg of right first time :) The V4 specs require a soft-start for Vcco, Vccaux and Vccint which I'm giving them. The MGTs require separate LDO supplies which will come up pretty instantaneously at power on, certainly way before the three main supplies. I was just wondering whether this was a known no-no and if I needed to spec some kind of soft-start for these supplies too. I have a V2 dev board which works fine with an LDO which comes up before the main supplies, I just wanted to make that the situation was the same with the V4.

-- Peter

Peter,

Sounds just fine.

we are still characterizing switching power supplies for the MGTs, and I wish I could recommend one, but we haven't finished all our work. Right now, it is best to treat the MGTs like the multi-GHz blocks they really are.

If you have any questions, feel free to email me directly,

Austin