Can dual 12V power supplies be used in parallel?

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Can dual 12V power supplies be used in parallel? [Copy link]

The current usage is that two 12V systems from different sources share one relay (HF105F), and each 12V output is converted by a transformer and DCDC. The usage scenario is: each 12V system can drive the relay alone or at the same time. Now the question is, will there be any problems when the 12V circuit systems from different sources are connected in parallel? What is the reason? Thank you!

chunyang

Do not connect in parallel directly, otherwise the power supplies will affect each other. You can use diodes to isolate them before connecting in parallel, and each power supply must be connected in series with a diode. There will be no problem if the relay drive voltage is reduced by one diode junction voltage drop, so you can connect in series without worry.

maychang

It is best not to connect them in parallel directly.

You can add a diode to each of the two power supplies, preferably a dual Schottky diode. The effect of reducing the relay operating voltage by one diode drop on the relay operation can be ignored.

maychang

Although two DC-DC converters with the same output voltage are connected in parallel, they will not be damaged because the internal rectifier tube of the DC-DC converter does not allow current to flow backwards. However, the output voltages of the two DC-DC converters cannot be absolutely equal due to component errors. If they are directly connected in parallel, one DC-DC converter will bear all the load current while the other DC-DC converter will be idle. This situation should be avoided.

Gen_X

If there is only this relay "load" and no other circuits, then the above analysis is correct. Don't worry, you can directly "connect in parallel" to form a logical OR.

However, if there are other loads, they will compete for the load through this parallel point, causing the one with higher voltage to be overloaded or even burned.

史蒂芬

Try not to connect in parallel. The discreteness of semiconductor devices causes differences in the internal resistance of the power supply, making it difficult to achieve completely consistent voltages.