I'm working on a device and I'm encountering some problems. Basically the device pushes varying currents through a variable load using a current source and an H-bridge. For safety purposes, the load needs to be grounded on both sides in case the power drops so that built up voltages over the load are able to dissipate.
Thus far I've solved this with the circuit down below, using two P-channel JFETs. If Vsupply drops below voltages on either side of the load, the P-JFETs will turn on and current can flow to ground. However, recently the requirements for the voltage supply have changed from 15V to 40V. I cannot find any P-JFET yet that complies with these voltage requirements.
I did consider using PMOSFETs instead of the P-JFET, however they do have the disadvantage that Vthreshold of voltage remains over the load. Also the choice for a JFET is not so easy, since many JFETs start to leak current if voltage over the load (Vload) starts to equal the Vsupply. The LSJ74A was one of the best options I could find, but it doesn't comply with the 40V requirements.
In short: I am looking for a solution that grounds both sides of the load if Vsupply drops to zero. Additionally, not leaking any current (or at least as little as possible), if Vsupply is at 40V. All while complying with a voltage-rating of 40V or more.
Any help is welcome, thanks already in advance!