Guru
Joined: 21/06/2018
Location: AustraliaPosts: 1310
| Posted: 09:57am 02 Mar 2019 |
Thanks Andrew - I learn't something today, must admit Spirito sounded a bit like voodoo stuff but I googled it and it is real ! I know well about linear planar versus trench when wanting linear performance but although this "Spirito" effect is closely aligned I had never heard of the gentleman or the effect named after him until your post.
Do you have any figures from your tests;
"dvdt can cause minor shoot-through at quite slow changes in Vdrain"
With regards to the slew rate (rise time) when you noticed the effect, just wondering how slow "slow" was.
A good description of gate resistor choice and some CRO shots are at this Link His conclusion about decent Gate drivers and low gate resistance concurs with these latest posts.
Note his third picture is headed " 1V, to the gate, with a 1 Ohm load resistor" - I believe he meant to say "1V, to the Drain, with a 1 Ohm load resistor"- then it made more sense. We are not operating at 300V but the large Cgd of our Mosfets and with multiple units in parallel has a similar effect at 48V with respect to gate drive requirements.
The post has moved on while I was writing this - there are drivers for IGBT's that have the negative offset you are after.
I bought 10 of the ZXGD3005's but when I saw their size I abandoned them for the TC4452 after I was reminded how small a SOT26 is. If you want 2, PM your address and Ill send them over.
If at first you dont succeed, I suggest you avoid sky diving....
Cheers Mike