ULN2003A: Connecting Isolation Diodes on the Input and Output

Christian, 

Thank you for sharing. I'm not sure where anode and cathode are but i am assuming as below photos. 

Typically you do not need to add any form supplementary diode from output to COM as it is redudant to the internal clamping diode. 

However, it will not cause any issue/harm and could even be beneficial as additional protection if are driving very inductive loads by shunting the extra current outside of the IC. 

This shunting effect will be most effective if you choose a diode with low Forward voltage, e.g. schottky,  as it will conduct earlier than internal diode. If that is your goal then this is a thing where you could even just have a DNP footprint just in case. If you are not driving inductive loads there is no point to use the diode.

And by "you" I mean the customer :)

Honestly even for inductive load / something like driving solenoid or motor, you most likely dont need to add it as the internal clamp diode is sufficient to protect against inductive voltagae spikes on the collector. 

Let me know if any additional questions and if not please i ask if you can press teh green button. 

Best

Dimitri 

Scott, 

Thanks for explaining the setup. I do not expect any issue with that setup, don't think you need to add diodes. 

If you get a chance to test it, could you report back here if you have issues and let me know your result?

best

dimitri