MAT04 for ASM-1's

[Terry Michaels]

Message text written by INTERNET:music.maker at gte.net
>Won't there be a current sharing problem with this?  I seem to
remember seeing an application with parallel transistors to 
increase the current handling capacity, but there were also small
ohm resistors to help share the current more equally.  Or is 
this not going to be an issue because they are all carved out
of the same rock?<

Hi Scott:

Current sharing is definately a problem with power transistors running amps
of current.   If one heats up more than the other, the Vbe decreases,
turning the transistor on harder, making it draw more current, heating it
further, eventually leading to a run-away condition.   That won't happen
with a MAT04, the current levels aren't high enough to cause significant
heating, and since the devices are matched and on the dame die, they should
all draw the exact same current.  For the MAT04, you definately don't want
to add emitter resistors, that would defeat the purpose of paralleling the
transistors.

I just had a thought on this, you could use just one of the 4 transistors
for the Vbe compensation, and parallel the remaining 3 for expo conversion.
 That would cut the Rbe by a factor of 3.

Terry Michaels