I bought a PCB module including a DS1307 real-time clock to evaluate if that RTC is right for the system I'm designing.
Here's part of the schematic:
The DS1307 works with a battery voltage between 2 V and 3.5 V. I use the module with a 3 V coin cell battery.
Resistors R37 and R38 make a voltage divider that turn the 3 V of the battery in about 2.5 V, and feed such voltage to the VBAT pin of the DS1307 real-time clock.
What's the use of such voltage divider? Why not connect the 3 V battery directly to the VBAT pin?
EDIT: I added the 5 V flag to the voltage live on the top of the picture.