S1 on nora, why and is it important?

Hi so I am ordering some nora’s, and I cannot find S1 (CUS-12TB) here in europe, so I was wondering why it is there and if I can just leave it out and change R14 to 0 Ohm like old nora design?

I have not been able to find similar footprint component either, so recommendations are welcomed.

ALso FYI S1 is not in nora bom list :slight_smile:

Taking a very quick look, it would appear to just be used to selectively bypass/disable the undervoltage lockout function @bz. I believe the DNS label indicates ‘do not install (stuff)’, so that’s why you’re not seeing it on the BOM. It’s likely just a design artifact from an earlier testing phase.

You should be good to go by just jumpering pins 1 and 2 together by any method you choose (assuming you want to retain the UVL feature).

Looking a bit further, given the low gate leakage of Q11 you should be fine with R14 of 1M, but I don’t see any harm using 0 ohm as you suggest if you want to mimic the original design.

Also, not sure where you’re located, but looks like Digikey has 10,000+ of the switches in stock if you did want to use it.

Hi Larry, thanks alot. I had not noticed the DNS label duh. I am in europe, digikey usualy ships form US i think, which has implications for in regards to tax and legislative stuff :slight_smile: