BQ27427: How to wire fuel gauge with charger ic correctly?

Hello,

I believe you are correct regarding the connection from the gauge to the charger using the SRX pin, however please ensure that you have C1 attached to the VDD pin as seen below:

I will loop in one of our chargers experts to look at the charger portion of this schematic.

Regards,

Anthony Baldino

Hi Anthony,

Thanks for the answer.

Having C1 for the power AC filter, I understood. I just omitted it for simplicity.

I want you to be on the same page with me for the SRX pin voltage level.

When charger IC tries to put high current when charge phase is on fast-charge mode, the voltage applied to the SRX pin would be over 4.2V regardless of the current battery voltage.

How do you think?

Hi,

With regards to the charger portion of the schematic:

It appears the schematic is missing a few passive components, namely the VIN capacitor (1uF), VSYS capacitor(10uF), and VBAT capacitor(1uF).

Best Regards,

Juan Ospina

Hi Ospina, 

I omitted it for simplicity.

I want you guys focus on the wiring and voltage level on fuel gauge IC's SRX pin.

Hello,

Do-Hyeong Kim said:

When charger IC tries to put high current when charge phase is on fast-charge mode, the voltage applied to the SRX pin would be over 4.2V regardless of the current battery voltage.

The flow of charge and discharge you depict above is correct, however I am slightly confused by this statement. Regarding the Vbat +/- 0.3 condition from the SRX pin, the 0.3V difference from this pin and the BAT pin is the maximum voltage drop across the sense resistor.

Regards,

Anthony Baldino

So connecting fuel gauge and charger ic like the above picture (in my original question) doesn't make any problem?

Is this TI official answer?