I have a KiCad error problem that I can't solve: error: the power output and power output type are connected
erreur: les de type power output et power output sont connectées
Asked
Active
Viewed 758 times
2
Transistor
- 168,990
- 12
- 186
- 385
hoyem
- 31
- 2
-
Please see the [help section](https://electronics.stackexchange.com/help). – JYelton Jun 13 '22 at 18:48
-
6Yes, KiCad says you can't connect two power outputs together, and you have connected two power outputs together. – Justme Jun 13 '22 at 18:48
-
Have you tried this circuit in the real world? – StainlessSteelRat Jun 13 '22 at 19:36
-
1You might also look at https://electronics.stackexchange.com/questions/290897/can-i-use-two-7805-ics-in-parallel-to-get-double-current-capacity for reason why KiCad indicates that this may be a bad idea – Seth Jun 13 '22 at 19:43
-
2what is your question? – jsotola Jun 13 '22 at 22:27
2 Answers
15
As an aside from the circuit's design being dubious: It's not exactly an error you have to fix, from the point of view of KiCad. It doesn't make KiCad "not work". KiCad is trying to help you avoid mistakes on your schematic. If you want to continue in spite of this guidance - that's up to you. You could suppress the error since this is an intentional design choice. And this error won't prevent you from linking the schematic to the PCB or anything else of that nature.
Paralleling 7805s in the way you show is not the best idea, since these devices have quite a bit of tolerance in the absolute output voltage value. This usually means that one of the 7805s will be running at the current limit - acting like a current source - and much hotter than the other one in the pair which will then act as a voltage source.
If you would like to parallel regulators so that they run at roughly equal currents, then this is one answer you might be looking for.
7805s are decades old parts and there are lots of app notes and designs out there that use them in creative ways. Recall that 7805 is a member of the LM340 family of regulators. This question covers increasing the current capacity of a 7805 regulator. The NatSemi app note AN-103 covers these regulators as well.
Kuba hasn't forgotten Monica
- 32,734
- 1
- 38
- 103
7
KiCad is telling you that you have two voltage regulator outputs connected together. It doesn't like that and it would be a bad design. You have two choices:
- Replace the two 78M05 (0.5 A) with a 7805 (1 A) type.
- Add 0.1 Ω after pin 3 on each. This will cause a 50 mV drop in voltage when 0.5 A is drawn from each regulator.
Transistor
- 168,990
- 12
- 186
- 385