I was working with the TPS40077 over the full temperature range of -55 to 120. The MOSFET Rds_on within this temperature range shifted from 11mOhms to 40mOhms.
-The current limit of this device is not meant to be exact, only a rough estimate for protection.
This protection (Rlim) is based on the value of the Rds_on, so the more the shift of the Rds_on, the more the shift of your current limit.
In this case at the temperature -55 you may have a current limit of 12Amps, where with the same configuration will give you under 1Amp current limit.
The way to try and maintain this rough current limit protection (if you plan on designing with these temperature ranges) is to find a MOSFET with very low Rds_on drift over temperature.