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     The SM72442 requires a +5V source to operate, now it has to come somewhere  since it is responsible for providing power to the rest of our systems. Looking at the schematics for the provided evaluation board the +5V regulation system takes its input directly from the solar panel's input. Thus in order for us to get the magical 99.5% efficient MPPT we must consider highest efficient +5v regulator configuration. The evaluation board provides +5V power via two stages: a switching converter that steps down to +10V and then the +10V is regulated to +5V via a LDO.

A good 4-switch buck-boost design

     The SM72442 makes makes use of a 4-switch buck-boost converter in order to control the power drawn from the solar panel. Since this is what allows the MPPT to operate it is important to create the most efficient design available, in order to make the most efficient design, we have to look for:

NMOSFETS with lowest possible Rds ON

     The 4-switch buck-boost uses an H-bridge to charge/discharge an inductor. In order to minimize power losses, we should look for an NMOSFET that has the lowest possible ON resistance while being able to handle our high power requirements (As almost all the power from the solar panel will flow though it). For our basis, the evaluation board uses an IRF3205Z-010PBF NMOS with a on resistance of 6.5m Ohms while being able to handle up to 75A of continuous current.