BQ41Z50: Design of a USBC charger for 4 cells lithium battery and fuel gauge. What about configuration of the BQ41Z50

Christophe LECLERCQ

Prodigy 30 points

Part Number: BQ41Z50
Other Parts Discussed in Thread: BQ25798, USB-PD-CHG-EVM-01, TPS25751, , BQ34Z100

Tool/software:

Hi,

My needs:

Design of a power backup system with 4 cells lithium battery (16850).
USBC PD for the charge. The system must be fonctionnal if only 5V is available.
Cells balancing and fuel gauge.

My researches:

The USB-PD-CHG-EVM-01 ( TPS25751 and BQ25798) seems to be a good start for the first two points.
The BP41Z50EVM seems to be a good idea for the last point.

Diagram with my ideas:

My questions:

Is my diagram OK or have you better ideas ?
The TPS25751 is configured by an external eeprom and this chip can configure the BQ25798 via dedicated IIC link: i'am right ?
For the BQ41Z50 i'am lost: how to configure it ?
- By flashing a specific firmware ?
- There is an embedded eeprom memory ?
- Something else ?

Thanks for you help.

Best regards.

3 months ago

0 Christophe LECLERCQ 3 months ago

Prodigy 30 points

An other question:

Is it possible to use an integrated battery pack (3 cells with integrated BMS) with this topology ? In this case how to connect the pack ?

0 Jose Couso 3 months ago in reply to Christophe LECLERCQ

TI__Mastermind 27321 points

Hello,

The inclusion of TPS25751 (USB-PD controller), BQ25798 (battery charger), and BQ41Z50 (battery fuel gauge and balancer) aligns well with your requirements for USB-C PD charging, cell balancing, and a fuel gauge. The connections via I2C and power lines seem conceptually correct.

Yes, the TPS25751 is typically configured via an external EEPROM

Please follow BQ41z50 EVM users guide to configure the gauge. https://www.ti.com/tool/BQ41Z50EVM

Yes, it is possible to use an integrated battery pack with a 3-cell configuration and an integrated Battery Management System (BMS) with your topology.

Please reference to the EVM schematic in the users guide for connections.

0 Christophe LECLERCQ 3 months ago in reply to Jose Couso

Prodigy 30 points

Hi Jose,

Thank you for your feedback.

Regarding to the pack connections i'am not sure. The EVM guide show the following information:

But in my case ( integrated pack with 3 cells, so only 2 wires) i don't know how to connect the pack. Indeed the BQ41Z50 needs intermediate connections for each cell as specified in datasheet: