Fast but small optocouplers?

On a sunny day (Sat, 01 Sep 2012 13:17:54 -0700) it happened Joerg wrote in :

I knowm, but I thought you took it maybe for output rise time :-) This thing really is not Ferry Vast, some years ago we discussed that issue here and somebody came up with really fast ones, maybe google still has it.

What about spiral turn PCB transformer, the prepreg constitutes approved isolation between the two turns. Needs HF (above 10MHz) though due to low magnetizing inductance if you need it that small

Cheers

Klaus

That works. But it would make EMC a challenge. I'll try the opto thing, looks like the Sanyo couplers might do the job. If not then I guess it'll have to be a transformer. Or maybe an ultrasound piezo transfer, that would be really high tech :-)

here

The Sanyo is fast enough, so most likely I'll use that one.

Cute! It's a miniature SFH6345 (which is, in turn, a 6N136 without the base pin...and its pesky capacitance). That'll come in handy for IGBT drivers!

Hmm, offhand, Digikey and Mouser don't stock it.. will have to look around.

Tim

Did you look at this one? They tout it as a pulse transformer replacement:

Don't insult the base pin. A b-e resistor really speeds up an opto.

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

The ones from Analog brag about their active refresh, which makes sure that, if they flip, they flip back to the correct state within some period of time.

We've used them (the ADI parts) with MOSFET drivers, where the dV/dt pushes the datasheet limits. We haven't seen them chatter at all.

Tim

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

I have full right to insult anything that breaks!

Resistors aren't necessary with these types, and taking it out to a pin is far more detrimental in typical applications: big edges really screw them up.

Note carefully, for example, how Fairchild rates the dV/dt of their 6N136.

As for empirical results, a 6N136 will do this in a gate driver:

Tim

P.S. Mmmm, Sprecher Abbey Triple. Geez, some fruit flies got in through the window, they're curious about it. Heck, I would be too. Now where's the fly swatter...

"John Larkin" wrote in message news: snipped-for-privacy@4ax.com...

I have full right to insult anything that breaks!

Resistors aren't necessary with these types, and taking it out to a pin is far more detrimental in typical applications: big edges really screw them up.

Note carefully, for example, how Fairchild rates the dV/dt of their 6N136.

As for empirical results, a 6N136 will do this in a gate driver:

Tim

P.S. Mmmm, Sprecher Abbey Triple. Geez, some fruit flies got in through the window, they're curious about it. Heck, I would be too. Now where's the fly swatter...

You claim that everything suggested is too big, but I just wonder, how you are going to handle the PCB creapage distances with very small (narrow) packages, if you intend to keep the _system_ level insulation ratings in the kV range.

I've used an Avago HCPL-0631 for a similar situation. Its blazingly fast. It does require 5V-ish power on the secondary side. In my case I solved that with a simple resistor + zener diode.

They hold 21,000 of them right now. Is that not enough stock? :-)

Partially by potting. I have space, but not as much as needed for a big fat HCNW137 chip or the like.

Yes, I looked at those. They have the usual problem, a whopping 0.500" length. It would be like trying to squeeze a Ford F-350 Crew Cab with a full length bed into a parking space for a compact car.

But you also had the space for these rather fat IC packages :-)

It also comes in an SO-8 compatible housing. Its a bit high but the footprint is small and it is a dual-opto so the footpring for each optocoupler is tiny :-)

But it's still too big and we only need one.

Weird, I had found the PC457L0NIT0F, which has the exact same datasheet, which is the -P0F, not -T0F.

Digikey has 23k and change of the -NIP0F, and 58k and change of the -YIP0F, which is VDE marked. Again, same datasheet and link.

Now I want to know what the hell is the difference! Nothing about part numbering in the datasheet. Sharp's website isn't helpful; datasheet specifies "corresponding Optoelectronic Application Notes", but there are none listed under this product type. And their listing shows the

Tim