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Combination Ethernet POE Extension and Step-Down Power Supply


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your documentation states: "The Ethernet Extension can be used together with a Step-Down Power Supply."
Does it mean that, when powering the stack with your Ethernet POE Extension and adding a Step-Down Power Supply to the bottom of the stack, I get stable 5V output voltage of the Step-Down Power Supply?


Edited by cl-
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  • cl- changed the title to Combination Ethernet POE Extension and Step-Down Power Supply

No, this is not possible by design with version 1.3 of the Step-Down Power Supply. It has diodes included to prevent feeding the 5 V output from the USB port of the Master.

If you happen to already have a version 1.2, it is possible because it doesn’t have the diodes yet.

What the documentation means is that you can have both in a stack and either of them will power the stack if the other one loses input power.

There are, however, a few bricklets that have 5 V outputs that are fed from any 5 V source in the stack, including the Ethernet PoE Extension. Have a look at the IO-16, Analog In and Analog Out bricklets. If you only need a 5 V output and don’t actually need the input and power supply of the Step-Down Power Supply, using one of the bricklets will also be the cheaper option. The only drawback of the bricklets is that you might not be able to draw higher currents from their outputs, depending on your cabling. The Analog In and Analog Out bricklets have 350 mA fuses for their 5 V outputs, the IO-16 has no fuse and will output whatever you can get across the cables.

Another option would be to just get a 7-pin bricklet cable and cut off the data and 3.3 V wires and only use it to draw 5 V from one of the Master’s bricklet ports.

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