Christoph Maier wrote:
Unlike digital watch logic, which consumes next to no quiescent current, a voltage multiplier that drives a LED draws substantial current. So the rds(on) of the MOSFETs is a serious problem, and you can't just use commercial off the shelf low voltage CMOS inverters.
Hmmmm, I went and looked up a bunch of the discrete MOSFET's on DigiKey, and you're right, the rds(on) is killer. I actually pulled a couple transistors from my bin, the rds(on) varies from an ohm to a couple hundred ohms. I can't match the markings on the low-end ones. They're probably ancient FET's. And, when I say ancient, I mean it. I've got some RTL (resistor transistor logic) and DTL (diode transistor logic) chips in that same drawer.
It looks like the rds(on) from an off-the-shelf, depletion-mode discrete is, at best, 75ohms. That's not going to work.
-a -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
