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How Do I Parallel the Outputs of Two Power Supplies?

Joining two power supplies in parallel can cause overheating, should one supply sink current from the other. This may be due to a slight output voltage difference between the two supplies. To avoid this, each supply should be connected to the load through a suitably rated power diode. With some supplies, the voltage feedback control loop can be extended externally on a separate terminal and this connection should be extended to the diode summing point at the load termination.

Things You'll Need

2 DC power supplies of equal voltage output
2 power diodes

Instructions

- 1
  Connect the power diode negative leads together to form a current summing junction. This is the point where the currents flowing from the individual power supplies will be added together before entering the load.
- 2
  Connect this summing junction to the load positive terminal.
- 3
  Extend each power diode positive lead to its respective power supply positive terminal.
- 4
  Connect the load negative terminal to each power supply negative terminal.
- 5
  Connect each power supply external voltage feedback control loop terminal -- should they be available -- to the diode summing junction.

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