MyPi 24V Operation
MyPi Power Input Range
One of the questions that comes up a lot is "Can we run the MyPi board with a 24V PSU?"
To answer this question we need to fill in a bit of detail on why the top input range is specified as 23V not 24V.
The power converter chips used on the MyPi board are AP6503 buck converters from Diodes Inc - see AP6503 Data-sheet - these parts have a wide input range with absolute maximum input of 26V.
However the data-sheet also gives a maximum recommended input of 23V and states that "The device function is not guaranteed outside of the recommended operating conditions".
We've had discussions about this with our local Diodes Inc field service engineer (who confirmed our thinking on the matter) and performed our own internal testing running boards for extended periods without system problem at 24.6V input (allowing for a 24V PSU with 2.5% accuracy)
In combination with a reversed input polarity protection diode the PSU input is also protected by a SM6T27A Transguard device, in order to protect to the internal devices from transient voltage spikes, this device has a stand-off voltage of 23.1V and a breakdown voltage of 25.7V, so protecting the input PSU devices from exceeding the absolute maximum values.
So whilst we cannot guarantee correct parametric operation at 24V over the entire temperature range (in line with the Diodes Inc data-sheet) on the face of it there doesn't appear to be a problem with doing so.
We would of course advise customers to carry out their own testing to ensure compatibility for their application.