Nice, re-drawn schematics of some Amigas are available
here.
Looking at the A4000T schematics around the RTC:
- in A4000T schematics there is option for either Ni-Cad or Lithium internal battery (a resistor or a diode is installed depending on which is used)
- for internal or external lithium usage there is (a resistor and) a diode, which should drop the voltage to about 3v
RP5C01 datasheet gives "Data preservation voltage" as 2.2-5.25v.
The A4000 schematics looks identical but the bit about the lithium battery is removed (also there is no mention of the external connection, which seems to be present in the CR-version).
