On a sunny day (Sat, 13 Jul 2024 06:53:01 -0700) it happened john larkin <jlarkin_highland_tech> wrote in <pf059j9jdrlh1744aj27noiurhsr5g9fr4@4ax.com>:

On Sat, 13 Jul 2024 12:02:56 GMT, Jan Panteltje <alien@comet.invalid>
wrote:

On a sunny day (Sat, 13 Jul 2024 07:50:52 -0400) it happened legg >><legg@nospam.magma.ca> wrote in <bgq49jpna5a8menqfc1t7br9ui92rf29ml@4ax.com>: >>

On Sat, 13 Jul 2024 05:06:26 GMT, Jan Panteltje <alien@comet.invalid> >>>wrote:

NASA’s flagship mission to Europa has a problem: Vulnerability to radiation
https://arstechnica.com/science/2024/07/peer-review-is-essential-for-science-unfortunately-its-broken/

MOSFETS are not as rad-hard as promised
Any of that in your projects?

Wrong link.

Sorry, this one should work:
https://arstechnica.com/space/2024/07/nasas-flagship-mission-to-europa-has-a-problem-vulnerability-to-radiation/

How do mosfets fail from radiation?

Probably gate puncture?

Enough rads to kill a mosfet would be bad news for people.

It is well known, you could use that sort of semiconductor as radiation detector,
CCDs make great particle detectors too, tried it.

Radiation Effects on the Power MOSFET for space applications:
http://marcelod.pbworks.com/f/radeffpowercmos.pdf
lasting treshold voltage shift...

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On 7/13/24 17:08, Jan Panteltje wrote:

On a sunny day (Sat, 13 Jul 2024 06:53:01 -0700) it happened john larkin <jlarkin_highland_tech> wrote in <pf059j9jdrlh1744aj27noiurhsr5g9fr4@4ax.com>:

On Sat, 13 Jul 2024 12:02:56 GMT, Jan Panteltje <alien@comet.invalid>
wrote:

On a sunny day (Sat, 13 Jul 2024 07:50:52 -0400) it happened legg
<legg@nospam.magma.ca> wrote in <bgq49jpna5a8menqfc1t7br9ui92rf29ml@4ax.com>:

On Sat, 13 Jul 2024 05:06:26 GMT, Jan Panteltje <alien@comet.invalid>
wrote:

NASA’s flagship mission to Europa has a problem: Vulnerability to radiation
https://arstechnica.com/science/2024/07/peer-review-is-essential-for-science-unfortunately-its-broken/

MOSFETS are not as rad-hard as promised
Any of that in your projects?

Wrong link.

Sorry, this one should work:
https://arstechnica.com/space/2024/07/nasas-flagship-mission-to-europa-has-a-problem-vulnerability-to-radiation/

How do mosfets fail from radiation?

Probably gate puncture?

Enough rads to kill a mosfet would be bad news for people.

It is well known, you could use that sort of semiconductor as radiation detector,
CCDs make great particle detectors too, tried it.

Radiation Effects on the Power MOSFET for space applications:
http://marcelod.pbworks.com/f/radeffpowercmos.pdf
lasting treshold voltage shift...

Radhard electronics is as much a problem of design as of component
and technology selection. In MOSFETs, the nett effect is positive
charge getting trapped in gate oxide, resulting in threshold
voltage shifting increasingly negative. In bipolar transistors,
radiation creates recombination centres in the base region, resulting
in a reduction of transistor beta at low bias currents.

The message is obvious: In MOS circuitry, anticipate threshold
voltage drift, so apply wide gate voltage swings for switching
MOSFETs and bias point feedback for linear circuitry.

In bipolar circuits, anticipate a drop of beta and use generous
bias currents. Avoid ICs with lateral PNPs, which are only barely
good enough to start with. It's a good rule to choose old designs,
because those were designed in an era when parameters were less
well controlled, and consequently admitted more variability in
parameters before failing.

This is a gross simplification, of course, but it gets you
quite far on the way towards rad-hard design,

Jeroen Belleman

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On 7/13/2024 10:44 AM, Jeroen Belleman wrote:

In bipolar circuits, anticipate a drop of beta and use generous
bias currents. Avoid ICs with lateral PNPs, which are only barely
good enough to start with. It's a good rule to choose old designs,
because those were designed in an era when parameters were less
well controlled, and consequently admitted more variability in
parameters before failing.

Are you able to choose old bipolar designs? With MOSFETs, the vendors
regularly do die shrinks etc. that you don't have good visibility to
unless you have a record of all the Part Change Notifications (PCNs)
that have occurred throughout the part's history.

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On 7/15/24 19:47, Buzz McCool wrote:

On 7/13/2024 10:44 AM, Jeroen Belleman wrote:

In bipolar circuits, anticipate a drop of beta and use generous
bias currents. Avoid ICs with lateral PNPs, which are only barely
good enough to start with. It's a good rule to choose old designs,
because those were designed in an era when parameters were less
well controlled, and consequently admitted more variability in
parameters before failing.

Are you able to choose old bipolar designs? With MOSFETs, the vendors regularly do die shrinks etc. that you don't have good visibility to
unless you have a record of all the Part Change Notifications (PCNs)
that have occurred throughout the part's history.

That's a problem, indeed. The manufacturer may change the
chip so that it still answers to the original specs without
telling us, and that may indeed completely change its
radiation hardness.

I was in the fortunate -if uncomfortable- situation of never
making large series of devices, and several times was able
to find enough old stock.

I remember being shocked by the fact that the newer TTL
chips, F, AS, ALS, what not, tended to die after 40Gy or
so, while the old standard and LS TTL would still work
reliably with more than a kGy.

Rad hard design has its challenges.

Jeroen Belleman

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On 7/15/2024 11:22 AM, Jeroen Belleman wrote:

I remember being shocked by the fact that the newer TTL
chips, F, AS, ALS, what not, tended to die after 40Gy or
so, while the old standard and LS TTL would still work
reliably with more than a kGy.

Rad hard design has its challenges.

I've been thinking about designing a radiation resistant counter.
Basically feed in a 32.768 kHz clock and be able to pick off bits that
will tell me when a certain amount of time has elapsed since the last
power on of the spacecraft. Just AND the higher order bits together if
I'm looking for intermediate times. So if I want to get up into the
length of days, I'm going to need > 32 bits. Any ideas on how to do this?

3.2768E4 Clock Input
0 Bit 1.638E4Hz 6.10E-5 Sec 1.02E-6 Min 1.70E-8 Hour 7.1E-10 Day
1 Bit 8.192E3Hz 1.22E-4 Sec 2.03E-6 Min 3.39E-8 Hour 1.41E-9 Day
...
29 Bit 3.05E-5Hz 3.277E4 Sec 5.461E2 Min 9.1022 Hour 0.3793 Day
30 Bit 1.53E-5Hz 6.554E4 Sec 1.092E3 Min 18.2044 Hour 0.7585 Day
31 Bit 7.63E-6Hz 1.311E5 Sec 2.185E3 Min 36.4089 Hour 1.5170 Day
32 Bit 3.81E-6Hz 2.621E5 Sec 4.369E3 Min 72.8178 Hour 3.0341 Day
33 Bit 1.91E-6Hz 5.243E5 Sec 8.738E3 Min 1.456E2 Hour 6.0681 Day
34 Bit 9.54E-7Hz 1.049E6 Sec 1.748E4 Min 2.913E2 Hour 12.1363 Day

A handful of flip flops and a SN74LV8154 32 bit counter gets me up to 35
bits terrestrially. What about space?

HCC4060B Rad-hard 14-stage counter/divider w/ oscillator +
HCC4020B Rad-hard 14-stage binary/ripple counter +
HCC4024B Rad-hard 7-stage binary/ripple counter
gets me 35 bits, but is that nuts?

Are there radiation resistant PLDs or tiny FPGAs that get used for
something like this? Are the old discrete logic families radiation
resistant enough? I have some experience with radiation resistant
memories and large SoCs, but not lower level logic.

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On a sunny day (Tue, 16 Jul 2024 13:14:53 -0700) it happened Buzz McCool <buzz_mccool@yahoo.com> wrote in <v76kbv$1duve$1@dont-email.me>:

Are there radiation resistant PLDs or tiny FPGAs that get used for
something like this? Are the old discrete logic families radiation
resistant enough? I have some experience with radiation resistant
memories and large SoCs, but not lower level logic.

Maybe have a look at the NASA site with info about the stuff used in the Mars rover:
https://science.nasa.gov/mission/mars-2020-perseverance/rover-components/
Clicking on top right 'Brains' selects this link:

https://science.nasa.gov/mission/mars-2020-perseverance/rover-components/#brains
quote:
Processor:
Radiation-hardened central processor with PowerPC 750 Architecture: a BAE RAD 750
Operates at up to 200 megahertz speed, 10 times the speed in Mars rovers Spirit and Opportunity's computers

There is more on the net, google Mars rover electronics.
Was interesting for me as to the camera they used.

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