Other Parts Discussed in Thread: BQ25820, BQ40Z50, EV2400
Tool/software:
Hi
I have been trying to connect the EVMs for the two devices together to form a battery charger/fuel gauge for a 3S Li-ion battery pack.
I have not found or seen a top-level diagram for the connections between the two devices and I think I probably have not understood the overall design philosophy behind the EVMs.
The BQ40Z50 has SMBUS comms and the BQ25820 has I2C. I am assuming they do not talk together(?) although looking at answer to other posts on similar chips, it seems they might. Are they expected to talk to each other on the I2C bus or is a host expected to interpret? Given that the EV2400 has separate outputs to talk to both, I assume they aren't designed to work together.
The other question is the connection issue - should the BQ40Z50 sit between the charger output and the battery pack? That is, controlling the power distribution to the individual cells? Currently, I have the BQ25820 connected directly to the cells (as it would be stand-alone) and the BQ40Z50 monitoring the cells. There is no I2C connection between the two. Therefore the BQ40Z50 does not have control over the BQ25820 - it is just monitoring. It feels as though there should be more to this.
So (in summary):
1. Is there a top-level diagram of the expected topology for a charger + fuel gauge?
2. Should the fuel gauge be controlling the charger?
Sorry for the simple nature of the questions - I have looked a lot and this kind of diagram seems to be unavailable. It may be my understanding is not enough but nothing I've read has even come close to specifying this kind of info.
Thanks in advance.
Max
