IGBT ??

[Ed Lansinger]

>Would someone of you EE types tell me WHAT an IGBT is ..

Insulated Gate Bipolar Transistor.  Essentially a cross between a
MOSFET and a BJT (oops, more EE-speak :) ).  All you need to know
is that you can connect this device directly to a normal CMOS output
on your favorite microcontroller to switch large currents (as would
flow through, say for sake of argument, an ignition coil).  The
required drive current is very low (zero at steady-state) as
opposed to a normal BJT transistor.  The heat dissipation is
very low for large switch currents because the voltage drop across
the device at saturation is only a couple of volts, as opposed to
a high-voltage MOSFET which would typically have a high drain-
source resistance in the "on" state and thus large power dissipation
for large switch currents.

The ones of biggest concern to DIYers have built-in transient
overvoltage protection diodes to clamp high voltages, like when
you leave the plug wires disconnected and try to start the engine.
I have a part number that works very well for this sort of thing
if anyone is curious.

>And where you can get them??

Motorola makes them, but good luck!  They are as hard to find as
hen's teeth.  I assume that's because they get Hoovered up immediately
by the car companies (my employer included) and their suppliers.

-------------------------------------------------------
Ed Lansinger
General Motors Powertrain
Powertrain Control Center
Premium V Software & Calibration Group
Milford Proving Ground, Milford, MI
elansi01 at mpg.gmpt.gmeds.com  8-341-3049  (810) 684-3049
-------------------------------------------------------