This week I have been up to no good again and the focus of my experiments have been the BQ25504 and BQ25570. The EVM we received from TI and E14 is that of the BQ25570 Energy Harvesting to Battery charger and has all the necessary components and a little too many jumpers. I connected the EVM to a solar panel as well as a superCap in the hopes of making use of power supply. This is what I came up with.
In the above video, it is clear that the LED which usually draws 30 or so milliamps can be run for so long on the SuperCap hence we need a larger one.
In a previous design challenge, I worked on a BQ25504 which is http://www.ti.com/lit/ds/symlink/bq25504.pdf a ultra low power boost converter suitable for energy harvesting circuits as well. In contrast, the BQ25570 also has a programmable buck converter which can be used to switch the voltage of the storage element to a fixed value which in this case was 1.8V . This time around the EVM is with me so a lot more can happen. Today I will take some time to experiment with charging Li-Ion Batteries and hopefully get better results. I would like to see the solar panel, BQ25570 and BTLE module work together to create a beacon of sorts but more details on that next time around.