I have a battery-powered wireless sensor system that sends sensor information periodically. One requirement is that it has to be functional at very low temperatures. Powering this system is a Tadiran TL-5903 lithium battery, which are batteries made to power systems at very low temperatures and supplies 3.6V.
When the sensor sends out a transmission by LoRa radio, it can consume a peak current of around 100mA+. At low temperatures, the battery cannot provide enough current to supply the load during transmissions and the battery voltage drops from normal operation of 3V to below the minimum operational voltage of the microcontroller (2.2V).
The current power supply IC is a buck-boost chip TPS63802. It takes in the battery's voltage range (2.0V to 3.6V) to an operating voltage of 3.0V. However, the IC doesn't have an input current limiter that can limit the current so that it doesn't take too much peak current from the battery. At low temperatures, we can't take in too much current from the battery or else the voltage drops substantially.
We tried putting a super cap at the output of the switching regulator but it doesn't seem to make much difference in the voltage drop when doing radio transmissions.
Is there an IC or a simple circuit that can limit the current coming into the regulator without dropping the voltage at the input of of the switching regulator?