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Inoue_PTX's avatar
Inoue_PTX
Icon for New Contributor rankNew Contributor
2 years ago

Power supplies don't rise monotonically

In ACEX 1K and Cyclone, the power supply don't rise not monotonically. The waveforms is shown below. Is the 3.3V in Cyclone "monotonically"? Also, the 2.5V in ACEX 1K has a slope that is always...
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FvM's avatar
FvM
Icon for Super Contributor rankSuper Contributor
2 years ago

Hi,
i'd refer to datasheets. ACEX datasheet e.g. specifies "Maximum VCC rise time is 100 ms, and VCC must rise monotonically" for VCCINT and VCCIO.

In other words, the device is not guaranteed to work correctly if you violate this condition. I won't expect damage, but configuration might fail.

As the shown VCCINT and VCCIO waveforms are nearly montonical, I won't expect failure. But it's obviously bad 5V regulator design that should be fixed.

Out of curiosity, are you newly designing with 20 years old ACEX1K and Cyclone or just servicing old instruments?

Regards
Frank