16 Oct
2012
16 Oct
'12
2:24 p.m.
On Oct 16, 2012, at 4:59 PM, Peter C. Wallace wrote:
A bipolar transistor will turn off too slowly for this
use, but a little SOT-23 MOSFET will work just fine (and a series resistor in the gate can
tailor the on/off slew rates) You can get ones with less than 5 pF output capacitance that
will easily sink 100 mA with less than .7V VOL
You could keep the bipolar from saturating with a Schottky clamp, but at
the expense of even more parts. I like the idea of a FET, but I haven't
looked very hard at the available parts.
but discretes would add to the assembly cost...
Certainly. Or, if one makes a kit, they add to the headache of the
consumer. :-) Some of us don't mind soldering upwards of 40 tiny SOT
parts, but some do.
- Dave