UD2.7 Thru Hole

[alan sailer]

I am working on a small DRSSTC (80mm) that is using the UD2.7C thru hole driver. I am having some strange problems that have me quite confused.

The driver tests very well with FB, OCD, LV cutout and gate wave forms all look textbook.

I have a basic question about the circuit. On the PC board the output drive for the GDTs is a single set of terminals.*

I have assumed that the circuit has enough current capability and is intended to drive the two GDTs (full bridge) in parallel.

The gate wave forms look reasonably good so I doubt that this is my problem.

But still it would be nice to know for sure.

Cheers.

* the only other UD2.7 that I have worked with is Loneoceans and it has two GDT outputs.

[Mads Barnkob]

What IGBTs are you driving?

A single GDT with 4 outputs can be enough to drive a SKM200 bridge, that is what I do in my DRSSTC1 with a UD1.3b

[alan sailer]

Mads,

Thanks for the reply.

I'm driving a full bridge SKM100.

I have considered doing what you propose but the coils are wound and mounted. I'm pretty
sure my problems are in other areas but I wanted to understand what the intended set-up of the UD2.7C thru-hole was.

Cheers.

[alan sailer]

To finish off this post, it turns out that the problem I was having was not related to the gate drive. The coil is running
(with other problems!) and I can pretty much state that the UD2.7C thru-hole design does drive two GDTs with
inputs in parallel. The outputs are driving a pair of SKM100 in a full bridge connection.

Cheers.