Electronics > Projects, Designs, and Technical Stuff

CPLD erase from Airport X-ray scanners

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EEEnthusiast:
I guess the cargo X-rays are much stronger than the carry on ones. The cargo X-ray machines are larger as they scan through larger consignments and it makes sense to make the X-rays stronger for them to see through metal sheets.

texaspyro:
There is a company (can't recall who) that makes a line of precision voltage reference chips that use the charge in a floating gate to set the voltage.   They have a report on how x-rays affect the voltage.  Also saw some independent tests.   I seem to remember the results said the technology was not all that precision.

EEEnthusiast:
Next time I will put a 2 inch solid lead block over my CPLD....
Oh...wait a minute... that will violate LEAD free rules... I'm screwed now..  |O

texaspyro:

--- Quote from: EEEnthusiast on February 04, 2020, 05:15:30 am ---Next time I will put a 2 inch solid lead block over my CPLD....
Oh...wait a minute... that will violate LEAD free rules... I'm screwed now..  |O

--- End quote ---

Tungsten or tantalum works better that lead

BravoV:

--- Quote from: texaspyro on February 04, 2020, 05:10:28 am ---There is a company (can't recall who) that makes a line of precision voltage reference chips that use the charge in a floating gate to set the voltage.   They have a report on how x-rays affect the voltage.  Also saw some independent tests.   I seem to remember the results said the technology was not all that precision.

--- End quote ---

Former Intersil (now Renesas), their product line of voltage references that use Floating Gate Array is affected by X-Ray.

-> AN1533: X-Ray Effects on Intersil FGA References

Interesting quote :

"Shielding and PC board solutions. The FGA package leadframe plus two planes of copper provide an excellent shield for radiation from one direction as shown in Table 5 on page 4. Protection for the device side of the board must also be considered. A shield of zinc foil or sheet, 250µm minimum can be placed inside the enclosure above the FGA which effectively filters the most damaging energy. An alternative to consider is a thick aluminum sheet, 10mm or greater, placed over the device side of the PC board."

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