Go Down

Topic: Overcurrent protection (Read 2970 times) previous topic - next topic


Mar 13, 2007, 08:45 pm Last Edit: Mar 13, 2007, 08:49 pm by jims Reason: 1
I slipped with a probe, shorted a power to ground, and burned a trace off my protoshield (sparkfun variant) today. Seems the first 7mm or so of trace from the +5v pin is the fusible link in the design.

I'm a bit surprised. I was running on USB power and I thought those were limited to 500mA. Perhaps PCB traces don't handle as much current as I thought.

So, for people making protoshields, I'm glad the shield failed before the Arduino, but...

It would be nice to have a resettable fuse to limit the current to something under the trace failure current. I looked at polyfuses but wasn't able to find one of an appropriate current limit that didn't have an unacceptably high resistance.

An alternative would be to beef up the +5 traces so they could handle the 1 amp or so that the onboard regulator makes, and hope the USB won't make more. It is currently a very narrow trace so it can sneak through the hole field. A wider trace would have to go around, but could be serveral times wider... heck, have both.



fyi the Arduino regulator is a 78M05, good for 500ma. It does have short circuit protection/current limiting. but that won't help with burnt traces...
But hey, what would building things in electronics be without the occasional smell of burnt PCB? :)


Go Up

Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

via Egeo 16
Torino, 10131