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I'm confused about how N-channel MOSFETs operate in BLDC circuits. enter image description here

Say we had MOSFETs that are being driven with Vg = 10V, and DC+ is 36V. Say we have Q1 and Q4 on at some instance (Through phase A and C). What would be the voltage at the source of Q1 (and drain of Q4)? From my understanding, due to the nature of mosfets Vgs > Vth, so would the source voltage be at most 8V (with the assumption Vth = 2V)?

The broader question is I'm confused how higher voltage is resulting in higher current draw/spins faster when it seems like Vgs is the limiting factor. (I know I'm probably wrong, but am confused).

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  • \$\begingroup\$ The lower legs gates can be directly driven with a LDO, say Vgs=10V, while the upper legs do need a charge pump or bootstrap circuit. Having a supply voltage that can't supply Vgs>>Vth it will burn the MOSFETs. \$\endgroup\$ – Marko Buršič Sep 16 at 8:28

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