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TE-0712 Power up

Started by Acam2014, November 07, 2016, 09:01:32 AM

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Acam2014

Hi!

I just started a new project with the TE0712-200 board and I'm experiencing some trouble with the board powering up after programming.
With a small design, the board drawing about 0,3Amp everything works fine after I download my configuration to the FPGA.
But with a little bit bigger design, the board drawing about 1Amp, I get an infinite loop with the board trying to power up after configuration and then failing, both LEDs flashes, then trying to read the configuration again, failing etc...

I guess my power source, a linear regulator is bad, but despite that I wonder if there is any configuration you can make to the TE0712 System controller in order to get it to power up "more softly"?
I drive both VIN and 3.3Vin from the same 3.3V  1.5A regulator.

Kind regards,
Jonas Nyberg

Antti Lukats

I am afraid the power supply is insufficient, while 1.5 may be OK in stable operation during the startup more current is needed, so you have a too big voltage drop. You may try adding really big C at 3.3V input but better to have a bit more powerful supply

Acam2014

Thank you for your fast reply!

Do you have any rough idea what the instantaneous current draw is at power up? How many x times the stable state?
I'm just wondering because in the near future I'm planning on developing a custom power supply for my board.

Regards,
Jonas

Thorsten Trenz

Hi,
on our own bases, we use always a 4A switch mode powersupply. This is sufficient for most of the designs. You may need more depending on your bitstream.

Best Regards,
Thorsten Trenz

Acam2014

Thanks for the info.
This will give me an idea of what to aim for.

Br,
Jonas

Acam2014

One last question,

I can see that you have "only" 47uF + 10uF capacitors placed on your baseboard TE703 at the output of the DC/DC. My design have a 22uF at the moment very near the FPGA module connectors but can of course be increased.
My finished design will be a separate power board with wires coming to the baseboard (where my TE0712 FPGA board is situated). I think my approach would need a lot more than 22uF because of the wires (about 5cm).
Of course also the transient response of the power supply will be critical, but I think I could ease things up with more capacitance.
Do you have any take on this?
Thanks again,
Jonas


Thorsten Trenz

Hi,
if your power supply can handle more capacitance, it is better to have more.

Best Regards,
Thorsten Trenz

itismamu

I have 12V input supply..can anyone please suggest me 3.3V regulator with 4A current as mentioned above?