[sdiy] Coping with diode drop(s) on Iabc input with LM13700/CA3080

Aaron B. aaron at zadzmo.org
Wed Sep 30 19:22:49 CEST 2020


If I'm understanding the problem correctly, the OTA is powered by +9
volts, the microcontroller by +5v. With the mirror sourced from +9 as
well, the diode drop will move 3 or more volts beyond the
microcontroller's power rail.


I may also be completely wrong about everything here. :)


On Wed, 30 Sep 2020 19:00:12 +0200
Roman <modular at go2.pl> wrote:

> Current mirror will only move the problem of coping with diode drop from gnd to plus rail
> 
> Roman
> 
> ---- Użytkownik Aaron B. napisał ----
> 
> > This will invert the polarity of the CV, but if that isn't a big deal -
> > drive the OTA through a current mirror. The PIC's output will sink
> > current through a programming resistor at the mirror's input;
> > the mirror's output then sources Iabc to the OTA.
> > 
> >  

-- 
Aaron B. <aaron at zadzmo.org>



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