CHAPTER 7-3: VBAT Domain(B)
324 FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E
Examples of power supply configuration
Figure 3-4 Example of Using Primary Battery as Backup Power Supply
Figure 3-5 Example of Using Secondary Battery as Backup Power Supply
The diode and resistor inside the dotted line box trickle charges the secondary battery.
When setting the resistance, check whether the secondary battery used can be trickle charged, and the
maximum current of trickle charging.
If the secondary battery used cannot be trickle charged, use it the same as a primary battery.
Notes:
− Turn off the system power supply before inserting or removing a battery.
− If a primary battery is used as the backup power supply, it is not recommended to connect the
system power supply to the backup power supply through a diode.