My system is powered from a wall adapter and backup SLA battery.
Since the voltage of the wall adapter is higher than the SLA, I have ORed the two so that the battery will be used only when wall is not available. In the event that wall is not available and the battery is discharged, I would like to disconnect the battery from the load to prevent further discharge. I could simply place a high side switch before the ORing diode, however I thought using an ORing mosfet controller would be smarter since it can do the ORing with better efficiency and act as a switch at the same time (win win!!).
I found the TPS2419 ORing contoller with enable and LM5050. The enable pin on these controllers allow me to turn the high side N-mosfet off, but to my surprise this does not disconnect the load as the mosfet is connected such that its body diode will conduct (see figure below). Every other ORing controller I have seen also uses the same configuration. The data sheet of the LM5050 even mentions that current will still conduct when the external mosfet is off.
I have also looked at power multiplexer ICs but they are rated for lower voltages.
My question is, is it even possible to use the ORing mosfet as a load switch? If not, why is the mosfet connected that way and what is the purpose of the enable pin?