TVS breakdown voltages for higher currents

the TVS to get your results- the zener sets the peak firing voltage, TVS is low voltage not critical except that its threshold for significant conduction exceeds steady state worst case maximum DC on line with sufficient margin so that SCR shuts off by holding current deprivation.

If I had a surge-rated zener that would be great. But it must take >10A current spikes.

--
Regards, Joerg

http://www.analogconsultants.com/

All I really have is the square-footage of an SMA package. The transistor is not trivial because a >10A spike must be snuffed out. Ok, could use a FET but still, that spike is no small feat.

--
Regards, Joerg

http://www.analogconsultants.com/

What about a voltage regulator?

Too large :-(

--
Regards, Joerg

http://www.analogconsultants.com/

the TVS to get your results- the zener sets the peak firing voltage, TVS is low voltage not critical except that its threshold for significant conduction exceeds steady state worst case maximum DC on line with sufficient margin so that SCR shuts off by holding current deprivation.

milliseconds. You obviously do not have enough high frequency loss on your input. The fix would then be a series ferrite bead with a high frequency capacitor shunt to ground to kill the Q. or simply put a R in series to lower the Q.

Jamie

how much current does it need pass in normal operation? would a fet and disconnect work?

-Lasse

That's not ringing, that's a crap power supply losing regulation and breaki= ng into oscillation. What's causing it to spazz out like that? Makes no dif= ference, this calls more for an LDO than a clamp - there is this product th= at will fit the bill:

About an amp. If it can be opened fast it could be done with one of thiose 3*3mm DFN FETs. But needs that some electronics, and there's just no space.

--
Regards, Joerg

http://www.analogconsultants.com/

[...]

It is not the power supply, it is a vehicle bus with load dumps, long lines, EMC filters and a whole lot of nasty stuff on it. Nominal operating voltage 28V.

Won't work, abs max is 105V so it'll go ...*PHUT* :-)

And I need it to let 1A pass.

--
Regards, Joerg

http://www.analogconsultants.com/

[snip] 63mJ is the typical energy delivered to the spark plug in your car. ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Okay, well there are a whole bunch of reference circuits using HV MOSFETs to handle that situation- none of which are single component unfortunately. And a load dump can put more than 1-2A into a shunt- way more.

into oscillation. What's causing it to spazz out like that? Makes no difference, this calls more for an LDO than a clamp - there is this product that will fit the bill:

Interesting chip. I can see where that would be very useful in automotive applications.. Very easy to add a power fet on the output.

I notice it looks like a souring reg only ?

Jamie

That's pretty slow; have you tried bundling your cables or re-examining the return line distributions?

One zener, one fet w/gate resistor, two diodes. Should solve tolerance.

60mJ doesn't seem like much of a threat. 250mW zeners were generally good for a joule. Maybe you need more time with the hardware. Measure current deliverable and rep rate of the supposed 80V threat. It should have the same timing.....

RL

handle that situation- none of which are single component unfortunately. And a load dump can put more than 1-2A into a shunt- way more.

Again, I do not want to shunt the load dump. I only want to shunt the ringing, and even there only the part that exceeds 90V would be fine.

--
Regards, Joerg

http://www.analogconsultants.com/

A problem with 90V zeners is that they usually only spec max current at very low levels of tens of mA, and most of all that their impedance is much too high.

--
Regards, Joerg

http://www.analogconsultants.com/

On a sunny day (Mon, 24 Sep 2012 07:13:09 -0700) it happened Joerg wrote in :

If you only want one frequency damped use a series LC to ground ;-)

--- Joerg: No SPace ----

But maybe you can s[l]imulate a series LC with a transisistor or something, that would then need a capacitator.

handle that situation- none of which are single component unfortunately. And a load dump can put more than 1-2A into a shunt- way more.

So a sharp clamp at +90V would be OK? How far above +90V does the source go, and what is its impedance? ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

handle that situation- none of which are single component unfortunately. And a load dump can put more than 1-2A into a shunt- way more.

Yes, sir.

The source will never go above 80V and it's impedance is unknown. Typically very low and the impedance as seen by the electronics will largely depend on the total cable length from source to electronics, which can be half a soccer field long.

--
Regards, Joerg

http://www.analogconsultants.com/

60usec ring-out was a simulated worst case scenario, it can also be shorter because this depends on the installed cables length. Which will be all over the map.

--
Regards, Joerg

http://www.analogconsultants.com/