Which OEMs Actually Use The OPA627 / Other Uber-High Slew Rate OAs?

[VictorQ]

...it's much more annoying with SO packages, and downright unfeasible with more modern SMT packages.

Infeasible is a strong word...

My first prototype for my BS.Eng. thesis was a dead bug job with an MSOP8 and four six pin SOT-23. It held together long enough to prove the concept, but yes it was a pain to wire up. Strong magnification is required. Also a real SMT soldering tip.

 

[JohnRoberts]

Great thread everyone, thanks

Hi Micheal,

The oscillation was seen by connecting a probe to the o/p socket, with the i/p socket shorted. My audio analyser picked up broadband fuzz at around -50-ish. I then hooked the scope probe and saw 18mV of something sine-shaped at 18Mhz.

The layout is on stripboard! The next stage is to give it to the PCB designer I work with. It seems daft to prototype anything with a 'relatively' quick opamp such as the 4562 on strip-board, but you have to get proof of concept somewhere, right? With anything faster I suspect you'd have to go for a multi-layer PCB from the start. Just the inductance of an IC socket can set off some OAs.

edit - trust me, you don't need to see the layouts. The moral of the story is that just a couple of mm here and there can trigger bad behaviour if the OA is quite fast.

This is exactly the problem I am having right now. Trying to prototype on a solderless breadboard with LME49990 and OPA1612 is a time consuming process!

I recall trying to breadboard a simple digital circuit using a solder less breadboard back in the '80s and the capacitance between adjacent pins altered my circuit enough to make it unusable.  Back in the day I laid out some standard footprint PCB to build prototypes that reflected reality a little better.

Now with SMD I find I almost have to go straight to a PCB design because the tiny SMD parts with heat sink pads on the bottom are too hard for me to deal with point to point.

JR

 

[Andy Peters]

This is exactly the problem I am having right now. Trying to prototype on a solderless breadboard with LME49990 and OPA1612 is a time consuming process!

That's why you want SurfBoards. Stick them to a piece of copper-clad board and you have an instant ground plane, too.

-a