Hacker News Reader

Comment by _huayra_ | Hacker News Reader

Do medical devices and auto tech use similar components? I understand there's a lot in common, but I would think that safety constraints for one domain would cause it to not overlap with the other.

Forgive my ignorance on this, as I am but a humble software engineer who is forever in amazement at how all ICs are basically flattened rocks we shoot lightning through to make it do math real dang quick...

View on HN

Often yes. "Medical devices" covers a large array of products from in-vitro/small implantable to things similar to laboratory equipment (think patient monitoring) or industrial (MRI and the like, autoclaves, etc). "Safety" is not really achieved on a per-component basis, but as a sum of the parts.

As for other comments in this thread, depending on your device, it can see a great deal of thermal stress (steam autoclaves) or vibration (MRI), and not all components in autos are experiencing the total vibrations from internal combustion engines. I've typically designed in components with extended temperature ranges, most commonly 85C+ or even 125C. This increases the reliability and extends the life of your product.

"Automotive-grade" typically means extra lot testing, and some parameters may vary in the datasheet due to the way the parts were validated by the manufacturer, even though they're technically the same part. For instance, I am using a Texas Instruments part that became nearly impossible to source. I had the automotive version in my bill of materials because at time of the design, it was the only version out. An alternative made by TI looked like a good fit, but a few key parameters in the datasheet didn't quite line up. It was because the automotive was tested at like 13.8V input whereas the newer "industrial" part was tested with 24V and slightly different loads. Same exact component, tested slightly differently.

Similar but not the same. There is an insane variety of nearly identical MCUs, for example. For an otherwise identical part, you can often get it in half a dozen or more packages. (i.e. the chip has different physical form factors in terms of how it attaches to the PCB, pin type and spacing etc... but the actual die inside is the same) Then there are subtle variants for a given MCU (differing types/amounts/speeds of RAM/Flash/interfaces etc.) The matrix of variants quickly gets out of hand. It's probably easily 10-50x (depending on the part) the number of variants Intel/AMD come out with each year. The autos also typically use parts with an extended temperature range.

For the subtle variants, I believe it's how they price discriminate. It's all the same part, but they use fuses to disable various peripherals. Way easier to do that than to fabricate a whole bunch of different chips.

Most likely when it's moderate/major features. Sometimes it can be as simple as a case of packaging (i.e. fewer pins so they can't bring everything out.) I've always assumed that some of the packaging options were driven by large customers who wanted something just a bit different for whatever reason. (PCB space, power consumption, just to be difficult... who knows)

In addition to the other good comments regarding medical/automotive overlap, is that often those chip lines have long lifecycle commitments built into them - ie. we promise to make this set of parts for at least 10 years. For both both of those customer areas, not having to redesign your boards and recertify devices on an external timeline is of value.

Sometimes, automotive components are just better QA'd (validated) regular components.

One would assume (or hope) that medical device components are also QA'd to at least the standard of automotive components.

One of the most common additional requirements on automotive parts is extended range, often below -20 C and above 70 C. That is often not relevant for medical products which operate only inside, near room temperatures.

And then there's also the vibration issue. I don't think most medical devices need to stand up to continuous vibrations like you'd have in an auto engine. If they are not soldered well, eventually things can loosen up and fall off, or minimally just break contact. I think the car industry is closer to the aero/space industry than medical industry.

It took 20 years but the circuitboard on my Nissan's dash had deteriorated enough to warrant resoldering. Now that is done, it is as good as new. It's remarkable how dash clusters look inside, absolutely pristine behind the plastic lens in spite of their environment.

Aero has a few unique issues that make car parts unusable. One is the lower bound of the temperature range, it's not unusual to see -55 celcius for an aircraft. And pressure, air is really thin at the 41,000ft most large aircraft are certified for.

Walked into an ice rink.

They measured kids temperature. 107 degrees.

After much confusion as to why the healthy looking child, and that no I wasn’t rushing her to the ER, they finally figured out that for head scanners don’t work right at 20 degrees.

The solution of course was to have someone sit on it when not in use.

A week later no more temperature scans.

Would you kindly confirm your story involves an outdoor rink? (My mind conjures a miserably cold indoor rink and I’m shuddering; the story as told is unnecessarily confusing because the ice rink detail is immaterial, the important detail is using the device outdoors in cold weather)

Indoor rink. An unusually cold one.

Was great fun with I was wearing T-shirt and shorts and they insisted I go to the rink to be checked. Then had to stand several minutes waiting.

Kid got dropped at door until they changed policy.

Yikes. Sounds like rink management has multiple problems.

well they are completely different standards. you wouldn't expect a medical device inside a human body to operate at 130C

Reply on news.ycombinator.com