Attaching a 5 volt supply to Proto Board.
CCraig
Posts: 163
I have a project that already has a 5 volt supply and I what to attach a SX Proto Board to it. Can I just tie my current power supply to the Vdd bus on the Proto Board? Vin is not needed
I'm not smart enough to know how the LM2940 will like that. I guess I should dig into·my current·PS and grab power before the 5 volt regulator and sent it to the LM2940 on the Proto Board. But as always, I'm looking for the easy way out.
In writing this, I decided to tear into the PS and add another output. I'd still like to know how the LM2940 would handle that reverse power. ie. +5 on the output, floating on the input.
TIA, Chris
I'm not smart enough to know how the LM2940 will like that. I guess I should dig into·my current·PS and grab power before the 5 volt regulator and sent it to the LM2940 on the Proto Board. But as always, I'm looking for the easy way out.
In writing this, I decided to tear into the PS and add another output. I'd still like to know how the LM2940 would handle that reverse power. ie. +5 on the output, floating on the input.
TIA, Chris
Comments
My expectation is that you should be fine doing what you have described, provided your other 5V supply is regulated. Here is why I expect that to be the case.
1.) The LM2940 has “Mirror image insertion protection.” I understand that to mean it is protected against damage if you supply power to the output of the LM2940 instead of to the input, which is what you would be doing.
2.) I have done this with other voltage regulators, though not yet one on an SX proto-board, and have not observed any ill effects.
Check it for heat buildup when you first connect it, but I expect you will be fine supplying your own regulated 5V.
- Sparks
I'm going to breadboard one, but it's been my experience that: just because it doesn't blow up, doesn't mean it's not going to blow up. I'll do it the right way. It's against my grain to get in there and hack it. i.e. cut the leads etc.
Thanks again, Chris