T
treez
Guest
Hi,
It is necessary to provide reverse polarity protection for a 24W Buckboost LED driver with Vin = 8 to 136VDC. (when vin <18v, then power can be reduced to 2W).
I find that the diode D3 is needed to mitigate the current that comes through the drain_gate capacitance of the reverse polarity fet at supply-ON time. –Especially when Vin is negatively greater than -100V.
The simulator may be over-exaggerating the D-G capacitance of the FET……do you know how I can inspect how much D-G capacitance is in this FET in the LTspice simulator? (and how the simulator changes this capacitance with VDG?)
LTspice sim and pdf schem attached.
It is necessary to provide reverse polarity protection for a 24W Buckboost LED driver with Vin = 8 to 136VDC. (when vin <18v, then power can be reduced to 2W).
I find that the diode D3 is needed to mitigate the current that comes through the drain_gate capacitance of the reverse polarity fet at supply-ON time. –Especially when Vin is negatively greater than -100V.
The simulator may be over-exaggerating the D-G capacitance of the FET……do you know how I can inspect how much D-G capacitance is in this FET in the LTspice simulator? (and how the simulator changes this capacitance with VDG?)
LTspice sim and pdf schem attached.