Hi
I have a Low-side driver application where we switch a solenoid on/off with a low-side N-channel mosfet. For failure redundancy we're actually using two N-channel mosfets in series. Someone pointed out to me that when both mosfets are commanded off, both their gates are grounded, and the bottom mosfet's source is grounded, but the upper mosfet source (bottom mosfet drain) is floating. They mentioned this could actually damage the top mosfet, because that floating node could float up over 20V (max Vgs rating). The load these are switching is tied to 28V.
Is this a real threat? I tried to attach a simplified schematic.
I have a Low-side driver application where we switch a solenoid on/off with a low-side N-channel mosfet. For failure redundancy we're actually using two N-channel mosfets in series. Someone pointed out to me that when both mosfets are commanded off, both their gates are grounded, and the bottom mosfet's source is grounded, but the upper mosfet source (bottom mosfet drain) is floating. They mentioned this could actually damage the top mosfet, because that floating node could float up over 20V (max Vgs rating). The load these are switching is tied to 28V.
Is this a real threat? I tried to attach a simplified schematic.