AP4413A

The AP4413 is a power management IC for energy harvesting applications, providing over-voltage and under-voltage protection for rechargeable batteries in ultra-low current consumption.
The AP4413 contains 2ch comparators with an operating current of 26 nA each channel. One comparator discharge from the OVP pin when the voltage of the rechargeable battery reaches the VDETH1 to protect over-voltage of the rechargeable battery. 
The other comparator starts supplying power by connection to the system when the voltage of the rechargeable battery reaches VDETH2, and disconnects from the system when the voltage drops to VDETL2. 
Therefore, when using a power supply in energy harvesting, it is possible to control the voltage of the rechargeable battery with only 52 nA of self-consumption current. AP4413 series has four threshold options: A, B, C, and D.