Hello :o

I've been spending the whole day trying to get some (you know, the magic sm=
oke) TPS2816 to drive the gate of a couple of (magic smoked the first) IRG4=
BC30S IGBT.

Then I got smarter and I currently limited the power to the TPS2816, to avo=
id frying the fifth of the lot.

But I still can't get the damn thing to work well, in practice I get MHz (o=
r GHz??) full output swing awful noise at the gate. I can provide screensho=
ts if it may be useful.

The TPS2816 is oscillating although I seem to have made everything the data=
 sheet asked me to do.

Not a PCB though, I'm prototyping to see what the IGBT solution can give me=
 vs the SCR one, so no PCB yet but the output pin of the TPS2816 driver is =
soldered directly to the gate of the IGBT, and at the power pins of the TPS=
2816 I'm using very short (2 cm) kinar wires to reach a generous bypass cap=
acitor. Vdd and Vcc are tied together, as I'm not using the internal regula=
tor but I'm feeding +14V directly. The ground is low impedance, star-topolo=
gy connected to the main ground of the circuit, not to the IGBT emitter (wh=
ich is at ground too). Parasitic inductances appear to be very low, as impe=
dances: although it's not on a PCB, I tried to be careful.

As I have to drive the input TPS2816 from a 3.3V PIC OutputCompare pin, I h=
ad to put a transistor (2N3904) inbetween. As the TPS2816 has an active pul=
l-up at its input, I connected it to the collector of the 2N3904, emitter t=
o ground, base to resistor which is connected to the PIC output. Should be =
rock solid.

But it looks awful at the scope.

I start to even doubt a TPS2816 can drive such an IGBT (the IRG4BC30S is a =
fast turn on (~20ns), slow turn off (~600ns) device).

50 nC total gate charge.. doesn't even look too much!

Maybe I'm missing something, as this is the very first time I deal with suc=
h a driver? Or even with IGBT's at all. At first I even wanted to design th=
e driver myself, but the TPS2816 looked just perfect, and I'm afraid I can'=
t match its performance.

Thanks for any hints,
Mario

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