Kirk Wallace wrote:
> So the FPGA would not be able to handle sinking 12 mAmps at 12 Volts?
> In other words, I would like to wire a 12 Volt supply to all of the SSR
> + inputs. Then wire each SSR - input to each FPGA sink socket on the
> controller card.
The FPGA is a 5 V IC.  I can guarantee, with 100% certainty, 
that applying 12 V, for even a microsecond, to the outputs will 
fry the FPGA.  I know, a wire touched at the CNC Workshop and 
popped the board I was using for benchtop demos.  Fortunately, I 
had brought some spares with me.  The 12 V powers the servo 
amps.  Now, in this case, there would be current limiting due to 
the SSR, so it might not pop the chip.  But, it would clamp the 
output line to +5 V, so the SSR would see 12-5 = 7 V when it was 
supposed to be off, and 12 V when supposed to be on.  This would 
cause it to be "stuck on" all the time, so it still wouldn't work.

Jon

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