Gecko 5V supply

Terry Toddy <tltoddy@...> wrote:

> I appreciate your assurance that the pc power supply will work just
> fine, but I have a switching power supply with +5 right in the control
> panel with my Gecko G201s. It would be easier to connect them to the
> +5v from the switcher than to bring +5 out from the pc.

Easier yes, but if you connect the ground you've defeated the isolation.

> Can this be done
> by simply connecting the Gecko +5 to the +5 on the swithcher and connect
> the parallel port ground to the common on the switcher?

This is the tricky part (that complicates things):

- The POWER ground and the LOGIC ground are completely separate
inside the Gecko. This is good (LOGIC & POWER are isolated).

- Keep in mind the LOGIC ground has to go back to the computer

- But if you connect +5 and GND from the switcher (ie POWER)
to the logic, the Gecko 201's are no longer isolated from the PC
(because the GNDs are now connected).

Maybe thats ok, better ask Mariss. But I prefer to avoid the complication
by just taking the LOGIC +5V from the PC, because the 201 was designed
that way (ie isolated LOGIC & POWER). And its not too much of a
coincidence I designed my breakout board to supply the +5V from the
PC (conveniently down the parallel cable) to handle this exact situation!

Doug Fortune
http://www.cncKITS.com