I'm attempting to use the LTC4359 to provide Reverse Polarity and Reverse Current Protection for the input of a DCDC converter that charges a battery. At the moment, I have spiced and prototyped something similar to Figure 10 in the datasheet. Please see the spice image below:
The DCDC converter, which is "off," is modeled as two diodes pointing towards the LTC4359 (body diodes of the MOSFETs). When the battery is present, the Reverse Polarity and Reverse Current Protection both work fine. But I run into a problem when the battery is not connected AND the input to the DCDC converter has been connected in reverse. In this case, Vout levels off around -0.7V (I believe ~two diode drops below ground). I have confirmed this in spice and on the bench. My concern is the bulk input capacitors on the DCDC converter are aluminum electrolytic, which are polarized and could be damaged by the negative voltage. Is there any way to prevent this.
I also confirmed it is indeed the body diodes that clamp the voltage to -0.7V, removing one lets the voltage wander even lower.
In the end, I'll need to combine this solution with that of Figure 11 from the datasheet to handle input voltages between 15V and 110V. If there is a better option please let me know.
Any advice is greatly appreciated.