altera, xilinx susceptible to power transients?

Just wondering...how susceptible are these RAM based FPGA devices to power supply transients, brownouts, etc? I am looking on Altera's website and have not found much yet.

Thanks,

Jeff

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Jeff
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Jeff,

If the transient is long enough, and large enough to upset a configuration latch, the power on reset circuit will see it first, and reset the device, cleaning it out, and preparing for a new configuration load.

Since we have been doing FPGAs for 20 years now, that is one basic we had to get right a long long time ago.....

The latches themselves maintain their storage down to ~ 300 mV, so anything that dips that low, trips the reset.

Aust> Just wondering...how susceptible are these RAM based FPGA devices to power

Reply to
Austin Lesea

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--Ray Andraka, P.E. President, the Andraka Consulting Group, Inc.

401/884-7930 Fax 401/884-7950 email snipped-for-privacy@andraka.com
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Reply to
Ray Andraka

I have been using 1.5V cyclone. Cyclone will reset some of its FF for a very fast transient on 1.5V rails. I am taling about voltage dipping well below 1V for more than 5-10nsec multiple times. I have never seen it going into the reconfiguration.

If transient is the problem, avoid using low voltage ICs, go for 2.5V or even 3.3V cores.

Naveed

Reply to
Naveed
5-10ns is a very narrow spike on the power, which should be caught mostly by your power supply bypassing. It is quite possible you have insufficient power supply bypassing on your board which is causing upsets or false clock transitions due to the narrow transients. Try it with much slower changes in the supply voltage, you'll see then that the chip continues to operate (although it slows down) as power is reduced until the reconfiguration reset trips.

Naveed wrote:

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--Ray Andraka, P.E. President, the Andraka Consulting Group, Inc.

401/884-7930 Fax 401/884-7950 email snipped-for-privacy@andraka.com
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"They that give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -Benjamin Franklin, 1759

Reply to
Ray Andraka

Andraka,

There is no amount of capacitors that will save me from the transients. My FPGA 1.5V supply share the same ground as programmable

0-800V power supply (different planes but connected). So if some body touches the 800V power supply with a probe for measurement, it creates spikes all over. You can reduce them, but not completely eliminate them.

If I did not have ceramics (in decades) all over, then these spikes would have been 2-3V at the FPGA, but they are about 1V now.

We don't mind these transients, as these boards will not be probed in actual use.

But if that was not the case, then I would have done one of the followings:

  1. Isolate the digital and power supplies (expensive option)
  2. Use a 5 or 3.3V core logic, and use expensive filtering scheme for Core supply (including inductors)

Thanks,

Naveed

your power supply bypassing.

board which is causing upsets or

changes in the supply

down) as power is reduced

Reply to
Naveed

your power supply bypassing.

board which is causing upsets or

slower changes in the supply

slows down) as power is reduced

--

--Ray Andraka, P.E. President, the Andraka Consulting Group, Inc.

401/884-7930 Fax 401/884-7950 email snipped-for-privacy@andraka.com
formatting link

"They that give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -Benjamin Franklin, 1759

Reply to
Ray Andraka

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