J
Joerg
- Jan 1, 1970
- 0
John said:Same here, the LT6700 had a glitch on the chip and I was the unfortunateJim said:Jim Thompson wrote:
Jim Thompson wrote:
Jim Thompson wrote: [...]
And Analog Devices modeling efforts are now managed by a MARKETING VP,
and they are ultimately heading to requiring simulation of their parts
ONLY on their web-based simulator.
That would be a marketing decision that borders on stupid.
I was there (San Jose) last August trying to convince them of the best
way to do modeling... let me see the real netlist and then I'd match
it behaviorally. The MARKETING VP nixed the idea.
(I even showed them various posts from this newsgroup complaining
about model quality... did no good.)
Then I assume they'll never understand why, when it comes to performance
and cost is not a major issue, I always default to LTC and never even
look at AD unless I can't find a chip at LTC. This is because LTC has
behavioral models that work in LTSpice and AD does not.
Same with TI. Who in their right mind would install and learn half a
dozen competing "free" simulators? If they can't understand that LTSpice
is the de facto winner, oh well.
PSpice will run ANY non-encrypted model, as will LTspice, HSpice, any
Cadence tool, and most amateur spin-offs.
If you run a complicated switcher non-behavioral (and I had to do that)
the sims take forever. For designing SMPS that clearly is not the most
efficient method.
Encrypting so a model will run only on the parent tool turns me off.
Me, too.
What do you do if you want to mix LT and ADI and TI parts on your
board? You're screwed.
On high end designs I never do that, and there is no need to. You can
usually get everything at LTC. Except for some hardcore RF stuff and
then that gets simulated separately.
If it has to be cheap then no special ICs are used anyhow most of the
time. For example, my first mass-produced device with a boost converter
revolves around a CD40106 as the "highest-tech" chip. There is no
dedicated PWM chip because that would have added at least 10c back in
the early 90's.
Joerg, sounds like LT is happy as a clam with you. You're a locked-in
customer. Enjoy >:-}
Well, yeah, at some point you have to pick one and run with that. I have
made my choice, and that choice is LTC.
"Most" of their stuff is good. I've had a recent situation where an
encrypted model works just fine on LTspice, but not on a PCB.
one who had to discover that the hard way.
In my case the LTC design engineers looked at it right away, found outThe FAE was flummoxed, referred the problem to factory... 4 months
have passed, no solution.
that it was indeed a bug, fessed up, apologized, rolled up the sleeves
and corrected things. That left a very positive impression with me.
Over the years I experienced numerous similar situations with other,
larger manufacturers. The classic solution was an attempt to cover it up.
They are, mostly. That is the reason why you can simulate switchers soI posted the problem on the LTspice list, but was basically told,
"LTspice, love it or leave it" :-(
All I've been able to find out is that LTspice encrypted models are
behavioral internally.
blazingly fast. This does come with pitfalls and (minor) risks but it
sure beats non-behavioral sims that take hours.
My LT3757 boost sim runs at about 15 PPM of real time. I need seconds
of sim to model my product, so I'd get two or three runs per week. And
I'd run out of hard drive for the RAW file!
If it's not super secret send it over and I'll take a look. There's
usually a way to speed things up, like by pre-charging a large cap and
things like that.
I've ordered samples.
It's a good chip, I don't think you'll be disappointed.