Brent, it's not the initial moment (t=3D0). But immediately after the turni=
ng
on.
Take a look please at his pictures showing the voltage across
the current sensing resistor:
http://orlandorobotbuilders.com/stuff/BIM2-01.jpg

So, on 50miliohm and about 280mV seems to be about 5.6A after turn on and
slow down to
1A in normal run.

If he measured the voltage drop across drain-source in the same time, he
may knew if that
current is producing the transistor dissipation or not.




On Thu, Nov 26, 2015 at 11:04 PM, Brent Brown <brent.brown@clear.net.nz>
wrote:

> On 26 Nov 2015 at 20:31, embedded systems wrote:
>
> > Schematic looks good.
> > I prefer a fast rectifying diode in anti-parallel on the load versus yo=
ur
> > zener on the MOSFET.
> > Maybe you should try.
> > At turn on you have 4x nominal current on the load.
> > Say the value of this current.
>
> How at turn on can you have 4x nominal current? Inductor theory tells me
> at t =3D 0
> current =3D 0.
>
> http://hyperphysics.phy-astr.gsu.edu/hbase/electric/indtra.html
>
> Not being critical, I'm just curious where your idea (rule of thumb?)
> comes from. It's
> not uncommon to hear people associating "inrush current" with inductance.
> In AC
> circuits it's a different ball game, assymetric currents due to phase
> angle at switch
> on etc.
>
> Brent
>
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.