RTC Power requirements - Connectcore 9P_9215

Does anyone have any definitive specification for the RTC power pin - specifically voltage limits and current demand in battery backup mode?

The only information I’ve found so far is the table on page 487 of the NS9215 data, which implies a current draw of nearly 40uA (32uA off 3V, 6uA off 1.8V).This seems very high!