I'm using a lipo battery in a project, and I want to include a sophisticated battery fuel gauge in my design. I have a battery input stage with a TI BQ24072 charge management IC and a linear down-regulator to 3.3v.
For the fuel gauge, I've chosen the TI BQ27421-g1 as I've had good luck with their battery charging IC. The typical application circuit is shown below:
I'm a little confused about the function of the SRX pin. The datasheet only has about 2 sentences about it. To make things more confusing, this diagram on page 20 says that it should be shorted to the BAT pin (sorry if the pin names are tough to read):
Here are my questions:
- Am I mis-reading the diagram on page 20?
- If I am reading the diagram on page 20 correctly, then how does the coulomb counter even work?
- If I don't understand the diagram on page 20, then how should the SRX pin be hooked up?