Smajdalf:
IIRC the chip NEEDs Vbat to be 0V when no battery is present.
Right, I read it today, in the Datasheet..
Smajdalf:
A huge resistor parallel to the battery pulls down the Vbat to 0V with no battery and drains only a small extra current if the battery is installed.
I see.
That makes sense, and explains the Resistor in parallel.
So now I understand both the Diode in parallel, and the Resistor in parallel.
Thanks to 6v6gt and to you..
Smajdalf:
Maybe there is a better solution (such as avoiding this ancient chip) but this one is the cheapest.
Right..