So, I need to supply the electron from a 34VDC power source, initially I thought about using a linear regulator like LM317 but I’ve noticed that the power supplied with this big “linear” step is limited down to 0.4A max.
I’ve found the LM2596 that have adjustable output voltages of 3.3V, 5V and 12V and have a good efficiency. I’ve noticed the Electron can be supplied up to 12V, what is the recommended Vin voltage?
Here in the forum a lot of people talk about using Pololu regulators, however I couldn’t find their reference desings, which can be a problem when we want to scale the production, since they are pretty expensive.
@ricsilvs, a linear regulator is not a good approach. The difference in voltage between the input and output is shed in the form of heat proportional to the amount of current provided by the device (Power = Vdelta x Load current). You are correct in wanting to use a buck regulator.
What is the source of the 34VDC power? How much current do you need beyond the Electron’s requirements? It is 2G or 3G?
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The source is a MDB bus (https://ccv.eu/sites/default/files/mdb_interface_specification.pdf). I couldn’t find the spec for the current it supplies, but I think it’s enough to supply the Electron since the same bus supplies all the peripheral inside a vending machine.
I’m using 2G electron but I want to make the design able to switch to a 3g electron, if needed.
@ricsilvs, Pololu is not open source. The MDB spec calls for a nominal 34VDC with up to 42.5v ripple voltage. You may want to check out TI’s regulators. Their datasheets include a reference design and layout rules:
http://www.ti.com/lsds/ti/power-management/step-down-buck-products.page#p212max=27.450980392156865;100&p451max=2;2.9&p238min=1;20&p238max=34;60&p634min=-5.5;5&p634max=5;92
There are plenty of designs available online. Adafruit publishes the schematics for many of their boards so you might want to check them out.
By using the Electron LiPo battery, the power supply is only required to charge the battery. The highest typical charging current is 500ma so your supply should be able to supply at most 1 amp (think wall charger).
@peekay123 I forgot to mention that I plan not use the LiPo battery, so I guess it needs to provide at least 10W.
Is there any disadvantage of supplying 12V instead of 5V?
@peekay123, you can supply 12v without any problem. If you skip the battery, your power supply will need to provide a peak of at least 2A. I believe there was thread by a member designing a board that also did not use the battery.
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