TIDUEO0C July 2019 – March 2021
Primary LiMnO2 batteries are becoming more and more popular in many IoT-enabled applications, due to their capability of providing high-current pulses up to 4000-mA peak (see the FDK CR17500EP Data Sheet) without suffering any performance degradation and without the need of external Hybrid-Layer Capacitors (HLC) or Super-Pulse Capacitors (SPC), which are required for LiSoCl2 primary cells. LiMnO2 batteries are viewed as less toxic, and do not lose capacity if mounted in a non-optimal position inside the end product.
The main disadvantage of LiMnO2 cells is the lower cell voltage, starting at about 3.2 V for new batteries at 23°C and going down to 2.0 V; the latter being the common value for a cutoff voltage (or end of-life).
Many common NB-IoT cellular modules, like u-blox SARA-N211 or Quectel BC95-B8 require a minimum supply voltage of 3.1 V or higher for proper operation. Thus, a voltage boost functionality becomes mandatory if a single cell LiMnO2 cell is used, which is typical for many residential-type meters, such as for gas, water, and heat or cold.
In many applications, two cells in-series may be preferred; here, a buck topology to down-convert the input voltage is suitable.