Charging 2S Lithium cells from 5V USB

Working on a side project that needs to charge 2 in series lithium batteries. Due to the nature of the enclosure. We don’t have access to the middle terminal.

Thinking of using the BQ25886. https://www.ti.com/lit/ds/symlink/bq25886.pdf

I am needing to connect the data lines of the USB to a microcontroller so this charging IC might not work.

According to some Ti forums the Data lines go Hi-Z after the BQ25886 does the power supply dance with the charger (PD 1.2).

Also seems if you tie the D+ and D- lines together on the BQ25886 it will default to the ILIM setting.

Looks like this could be a decent solution. Going to buy the BQ25886EVM evaluation board and see if it works how these 4 year old forum posts say it does.

Other suggestions?

Ordered a BQ25886EVM from digikey

One of the first times I have seen ground pad vias for center pads on a IC be suggested on a manufacture recommended footprint. They are catching on!

Getting the footprint designed.

Digikey shipping notification :eyes:

I got the evaluation board to work with my 14500 lithium cells.

Left test equipment is a programmable load simulating the device I am working on. Multimeter is reading the cell pack voltage, powersupply is simulating the supply from a USB Type-C connection with the CC1 / CC2 pins pulled down with 5.1K.

Seems to be working well. Time to spin a little test board.