I know how high side mosfet and driver and low side mosfet and driver work. I was wondering if it would be possible to drive a load like this: first the power supply, then comes a high side mosfet with its own driver, then comes the load, then a low side mosfet and driver, and finally ground...
The reason is that I dont want my load connected to either the power or ground when it is not driven...
If the high-side driver uses bootstrap diode/cap to power an n-channel MOSFET
then probably not (though some driver chips such as the HIP4081 have an auxialiary charge-pump not reliant on PWM).
If you mean a p-channel high side MOSFET and an n-channel low-side MOSFET, then
yes, it will be possible.
Note that the load, when off, will be semi-floating (leakage currents may be in
the microamp range for a power MOSFET, for instance, and you cannot take the load
outside the range of the power supply due to the body-diodes of the MOSFETs. There
is also source-drain capacitance in a MOSFET even when off to consider.
Thanks for the reply,
The second option with P channel and N channel mosfet is what I meant.
Is there any application notes about the circuit setup of this kind. I dont really care about the leakage currents anyway. Just as long as load is not connected to power or ground is good enough for me.
FardinB:
Thanks for the reply,
The second option with P channel and N channel mosfet is what I meant.
Is there any application notes about the circuit setup of this kind. I dont really care about the leakage currents anyway. Just as long as load is not connected to power or ground is good enough for me.
Thanks
The point is it is connected via two big diodes! It can float between power and ground but
not go above the positive rail or below ground without forward-biasing one of the diodes.
As i understand you want to make a circuits like the attached one.
Why do you not want one side of the load connected when not driven? For safety reasons?(thats he only reason i can think of) In that case remember MOSFETS are NOT switches, they do NOT galvanically disconnect. In this case you would be better of with an relay for disconnection an one MOSFET for control.