Any insight for Automotive Sensor Inputs/ Front-End Protection.

Also Transzorb. And ST calls them Transil. It's trade names, like Kleenex or Kim Wipes.

No canned answers. It depends on the circuitry. ...Jim Thompson

Sure it does. But it ain't rocket science. There must be a resistor, then a TVS to GND, then another resistor, then LED to GND. The latter resistor is sometimes part of the SSR already.

Hey, anyone else have issues with a Digikey order today? I was on the phone with their IT for over an hour, they were becoming frustrated as well, still no answer what's wrong. Had to order at Mouser now.

=A0 =A0 ...Jim Thompson

=A0 =A0| =A0 =A0mens =A0 =A0 |

=A0 | =A0 =A0 et =A0 =A0 =A0|

=A0|

=A0 =A0 =A0 |

Thank you all for the input, a little more on the circuit . Sensors are pressure switches/Temp that are connected to Vbatt. Pressure High=3D relay that switches Vbatt on/off. No current Limit. So I was thinking it would be best use opto. HSR312 SSR, Vr=3D7v, Vf=3D1.6V , control current approx 2mA.

Automotive opto front end for Vbatt switched with no current limit

Bav99/ TVS with a current limiter suffice? ? polarity protection p channel fet as well? any choice on fet, dmos only? thks

Who the frick needs a TVS? ...Jim Thompson

Entirely depends on the SSR. If it's a 12V input version and abs max sez you'd be gitten a *PHUT* sound at 30V you better put somethin' in there :-)

Do not forget protection from 48V nad reverse polarity!

Ah, you don't directly clamp the battery voltage? Too bad, that would have been another psshhh pop phuttt time... Well, maybe not that long :-)

Ah, I knew you were going to that :-)

TVS diodes. Transorbs is another name for them.

The 1.5k series seems to work nicely..

Do you actually need to do anything? LEDS will survive brief overcurrent just fine. If you size the LED resistor for 12V operation near the 2mA, you will have to get up to 100V or so to even get to its rated 25mA maximum. Any such pulses will be very brief, the LED won't mind.

I would just use a series resistor and connect a signal diode in anti-parallel across the LED.

There you go!

So many posters here want to make simple problems difficult... TVS's, etc :-] ...Jim Thompson

Those posters tend to design reliable electronics :-)

Figure 1, for a dose of reality:

Usually an LED survives that. But sometimes, especially when dumps happen in rapid succession, it doesn't. I don't have too much experience with automotive stuff for passenger cars but I do with electronics for larger vehicles such as aircraft. There, a non-TVS design is most likely going to hit the fan before it ever sees its fuselage mounting spot. At the RTCA test lab.

Nonsense! Find a single one of my chip designs that's ESD sensitive... including those I designed in the '60's.

Learn to read. Particularly my automotive patents. Not a single TVS in sight.

Circuits should be designed from the outset to survive. After-the-fact patches, like TVS's, are for amateurs :-) ...Jim Thompson

Can you give me part number, price and distributor (_with_ reel stock) of a Jim Thompson open drain SSR?

What has this thread to do with your automotive patents? Us guys have to use what's in stock here and now, not what's on a patent or what a company uses proprietarily. Because the client's purchasers have to be able to buy it. We can't bake ourselves a new chip every time we find that one is sub-par (and a lot of chips are).

It is occasionally cheaper to just plop down a TVS ;-)

Seems like you haven't designed such stuff for aerospace yet. Example: How is a PWM chip that only comes in a 40V edition supposed to survive an RTCA/DO-160 surge on a 28V supply rail? Yeah, you can make an over-voltage cutout around an n-channel plus half a dozen other parts. The smart and frugal engineer does that with one resistor and one TVS, to the tune of about 15 cents grand total.

Lets see.

Series resistor and diode = 2 components

TVS diode = 1 component and they come in bi or unidirectional.

Hmm.

All of my standard parts are listed on my website. OEM parts are listed by function but have no public part number.

As for SSR's, I've designed only two types... one type on Hubble, one type on a Honeywell Satellite Division spinner/launcher... you know, get them up there, spin, then boom, blow bolts. Nary EVER a failure :-)

I was designing for aerospace whilst you were still in knickers :-)

Check the facts before you burp. ...Jim Thompson

See, no publicly available SSR from your desk. Now where does that leave the OP?

BTW, my stuff with TVSes in there doesn't fail either. And it's really low cost :-)

Then you should be intimately familiar with DO160. Yet you haven't answered the question above, how you would solve that situation for 15c or less without a TVS.

How did the Romans say? Hic Rhodos, hic salta.

That'd be _way_ after my time in aerospace.

What is it you have running in any space vehicle?

What is it you have running in any car electronics?

Perhaps you have something in an implant. I do. ...Jim Thompson