On Wed, Feb 6, 2013 at 4:16 PM, Sergey Dryga <sergey@dryga.us> wrote:
> Mark Rages <markrages <at> gmail.com> writes:
>
>> You are measuring current upstream from the output transistors, so if
>> you go BJT you will have error introduced by the base current, which
>> will be added to the output current.   The resultant error may be
>> acceptable with Darlington outputs.
>>
> Would not the base current sourced by Vsupply, and, therefore not measure=
d in
> the collector current?  This assumes that output transistor will be npn
> connected as emitter follower, of course.

Yes.  Extra unmeasured current will be delivered to the load,
introducing an error in constant-current mode.

Regards,
Mark
markrages@gmail
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