BQ27411-G1: I2C Address for two slaves

Shibin Varghese

Part Number: BQ27411-G1
Other Parts Discussed in Thread: TCA9543A

Hi Team,
I am using BQ27411DRZT-G1A in one of my products.
We have two batteries in the product primary and secondary and both are rechargeable batteries.
I want to use BQ27411DRZT-G1A as the fuel gauge for both batteries to monitor their charging, discharging, SoC independently.
A single I2C bus is used for communicating the file gauge with the MCU.
If I use the same chip twice, I think an address issue will be there in the communication since they both have the same slave address.
Is there any method to solve this issue?.

over 3 years ago

0 Dominik Hartl11 over 3 years ago

TI__Guru 61006 points

You'll have to use something like https://www.ti.com/product/TCA9543A to use two gauges with the same I2C address on one I2C bus.

0 Shibin Varghese over 3 years ago in reply to Dominik Hartl11

Intellectual 835 points

Hi Dominik,
Thank you for your reply.
Ours is a battery-operated system and we are concerned about the BoM too.
Is using an I2C switch is the only solution?
Some chips like BQ27411DRZR-G1A and BQ27411DRZT-G1A are available in the market.
What is the difference between these two?.
If TCA9543A is mandatory, the same is not available in Mouser or DigiKey.
Else can you please suggest a Battery gauge with an I2C interface for a 3.7V nominal voltage LiPo battery with programmable address or chips of the same type with different addresses?.

0 Dominik Hartl11 over 3 years ago

TI__Guru 61006 points

The only difference between DRZR and DRZT is the size of the reel if you buy a full reel (DRZR is 3000 unit reel, DRZT is a 250 unit reel). The chip itself is identical.

The TCA9543A is just one example of an I2C switch. Another example is https://www.ti.com/product/PCA9543A

0 Shibin Varghese over 3 years ago in reply to Dominik Hartl11

Intellectual 835 points

Hi Dominik,
Thank you for your reply.
Is using a switch is the only solution here?.
Do TI have chips with hardware programmable I2C address?.
Can you please suggest a Battery gauge with an I2C interface for a 3.7V nominal voltage LiPo battery with programmable address or chips of the same type with different addresses?.

0 Dominik Hartl11 over 3 years ago in reply to Shibin Varghese

TI__Guru 61006 points

TI doesn't have a single cell gauge with configurable I2C device address.

There's a multi-cell gauge, https://www.ti.com/product/BQ40Z50-R2 which has configurable SMBUS device address.

All other gauges need a bus switch if you want to use several on the same bus.

0 Shibin Varghese over 3 years ago in reply to Dominik Hartl11

Intellectual 835 points

Hi Dominik,
Thank you for your reply.
The I2C address of the BQ27411DRZT-G1A is 1010101. Is there any other single-cell fuel gauge with I2C interface with another I2C address so that I can connect it to the same bus????
Even BQ27500DRZT-V120G4 has the same I2C address

+1 Dominik Hartl11 over 3 years ago in reply to Shibin Varghese

TI__Guru 61006 points

There isn't a recent (as in <10 years old) impedance tracking single cell gauge with different I2C device addresses.

0 Shibin Varghese over 3 years ago in reply to Dominik Hartl11

Intellectual 835 points

Hi Dominik,
Thank you for your reply.
From your reply, I hope the only scope is to use an I2C switch or to use a battery fuel gauge from another vendor.
Anyway, I have read the datasheet of the PCA9543ADR.
I have some doubt and I will post it as a separate thread.

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BQ27411-G1: I2C Address for two slaves