Hey electronics guys (OT)...

[Amphiprion]

Does anyone know of any good electronics-specific forums? In addition to the audio electronics I'd like to start discussing here, I've got some questions on electronics that aren't quite appropriate for this forum (they're just not terribly related to audio).

Right now I've got to design a constant current source, of variable current (controlled by a uC), that will deliver 0-100ma of current into a 0.1ohm load (10mV across load max). And it has to be as efficient as possible. I'm wondering where I might find a good discussion forum to answer these kinds of questions so I don't have to abuse my audio forums with these OT posts.

Thanks!

[JonMarsh]

How efficient? Efficient enough to justify the use of an SMPS converter with a transfer function that is essentially a current source (variable dependent on switching frequency) , or just a low voltage linear circuit running off how much Vb? For the latter, a cheap current mode or voltage mode DAC outputting into a current mirror with a defined current gain transfer ratio might be the easiest thing to do- but how much precision or accuracy do you need? Beyond a certain point, you'll need closed loop control.

Insufficient data for meaningful answer...

[ThomasW]

Mark,

Prior to Jon becoming a big time 'manager'.... ,
this info was at the end of his company emails..... :B

Jon M*** H******
Senior Applications Engineer
Power Management and Supply
Infineon Technologies North America

[Amphiprion]

Sorry, we have insufficient knowledge

They want it to operate at 3.3V. Battery powered, so voltage supply may be as low as 2V. This is to drive an electrochemical pump in a field usage device, doesn't need to be terribly accurate, precise, or clean - just efficient. 5% or more innacuracy may be acceptable, closed loop control not necessary. Cost not an issue.

I guess I don't even really know what my options are, never even heard of the variable switching freq SMPS idea. At this point I am searching the net at places like EDN for ideas. The current mode DAC into a current mirror sounds like an idea I could easily manage. I really have no knowledge of CCS stuff beyond basic current mirrors...

[Amphiprion]

Thomas,

That's why I ask these questions here and not at, say, DIYAudio where everyone is an 'expert' whereas here we have experts.

Though I really should find a forum so I don't post so much OT stuff here. As I start branching out into more diverse projects here at work questions will become even crazier (my HV switch was actually doing 6.5kW, 200ns pulses the other day before the control board fried).