AFE11612-SEP: Single Event Functional Interrupt (SEFI) Characterized

Hi Alex,

I've asked the people in charge of the radiation testing to provide more information on the SEFI testing. I'll let you know what they say.

Thanks,
Erin

Hi Erin,

Thanks for this information. I realize my question is actually a two in one:

1.) What are the SEFI scenarios for the AFE11612 and how can we implement the device with this in mind?
2.) What are the potential effects of SEE on the DAC outputs?

I think you have answered my second question. I don't actually know what SETI testing is, my guess is that testing for Single-Event Transient effects? My interpretation of your response is that the inclusion of a low-pass RC filter on the DAC output will prevent the the transients from coupling into the rest of the system. In my implementation the DAC outputs are used to drive a high-voltage amplifier with limited bandwidth, so a 2 us transient is too fast to cause a meaningful change in the amplifiers output. I just verified this in simulation.

I think my first question is still unanswered. I am mainly interested in the SEFI characterization from the approach of implementing the firmware driver for the AFE11612-SEP.

Let me know if this makes sense,


- Alex

Hi Alex,

Erin is reviewing this now and will provide a response soon. 

Best,

Katlynne Jones

Hi Erin,

Thanks for sharing the abstract, it helps explain the SET effect and allows us to design a better implementation of the AFE11612-SEP.

I am still confused about what the term "Single-event functional interrupt (SEFI) characterized up to LET = 43 MeV-cm2 /mg" specified in the first page of the AFE11612-SEP datasheet. The abstract briefly mentions increased current draw due to register flips: "The supply current excursions seen were due to register flips experienced by device which resulted in configuration change of device as shown in the Figure 3 & 4." The next sentence follows with: "The supply currents returned back to prebeam levels after reconfiguring the device to original register settings.".


What I am trying to understand is twofold:

1.) Do we need continuously check and reset of the AFE11612 configuration due to SEFI/SEUs to ensure the DAC outputs do not change from their set value?
2.) If the device does experience SEFI/SEU event, what is required for recovery? A.) Rewriting/reconfiguring the devices registers? B.) Resetting the device via nRESET pin and then rewriting/reconfiguring the registers? or C.) Power cycling the device and then rewriting/reconfiguring the registers.

Our application consists of feeding the DAC signal into a low bandwidth power amplifier which is used to drive mechanical actuators and precisely position optical components. The application can not afford physical changes to these optical components due to SEE effects on the DAC driving them.

My takeaway from the abstract is that we should be frequently re-writing the DAC registers to the correct value in case they get flipped. We should also add a low pass filter to the DAC outputs to help mitigate fast DAC glitches from coupling into the amplifier. Does this sound reasonable or should we be looking at another device that is less susceptible to glitches on the DAC output?

Thanks for your help,


- Alex

Hi Alex,

Going to try to get this information to you today. I'm not 100% sure of this, but my assumption is that:
1) Yes, you will need to continuously check for these events
2) I believe you will just need to rewrite the registers, wouldn't require any resets.

Thanks,
Erin