HV / LV side to 3.3V - Githubissues

LibreSolar / mppt-2420-rc

Solar/Wind MPPT charge controller for DIN rail mounting

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HV / LV side to 3.3V #10

Open BernhardEllmann opened 4 years ago

BernhardEllmann commented 4 years ago

Page 3 page of PDF "mppt-2420-rc" (sheet "/Power Supply/") defines "HV +" and "LV +" as inputs to the sub-circuit; on page 1 (sheet "/"), these are linked to "DCDC_HV+" and "DCDC_LV+" resp.. The circuit board (version v0.1) is hardwired accordingly.

At the same time, Page 3 states: "Use voltage from low side if available." (blue text on the left) This seems to offer a choice which is actually not available.

Please explain.

martinjaeger commented 4 years ago

The Power Supply sheet uses the name HV+ internally, but it's connected to the DCDC_HV+ net on the top level schematic.

The circuit around Q9 in the Power Supply sheet "chooses" automatically, which rail (HV+ or LV+) it uses for internal power supply. If LV+ is available (>around 12V), it is used instead of HV+ to increase efficiency.

BernhardEllmann commented 4 years ago

well, that's a nice feature :)