BQ27426: I2C address conflict with bq27742

  Yes, these 2 gauge parts have exact same I2C address. If your design has to use 2 gauge parts on the same I2C bus, then we have a new gauge part bq27743 for your design. Please let's know if you need datasheet and EVM for the new part. 

Thanks!

Phil

Hi Phil:

OK~I'll suggest customer whether could change the design for bq27743.

But if the design is fixed, is there any way to prevent the conflict issue for this same I2C address?

maybe you could try using an i2c multiplexer

Hi Phil:

thanks! Could you provide me the datasheet for reference firstly? (since like this P/N isn't released yet)

Hi Onyx:

Thanks, I just find even bq27520, bq27531, bq27426, bq27421 have the same I2C address;
Does that mean we can't use 2 gauge solution in a same project?

Hi Kay,
No you can't. you have to use an i2c multiplexer if you absolutely have to.
thanks
Onyx

Here are a few options to get around the duplicate I2C device address issue:

a)     If your processor has a second I2C interface, it can be used to control the second gauge on a separate bus.

 

b)    If you don’t have an extra GPIO and only have one I2C interface, you could use one of our I2C port expanders.  The TCA9543A is a great two channel device for such a project.

TCA9543A: 2-Channel I2C Bus Switch With Interrupt Logic and Reset

Product Folder: http://www.ti.com/product/TCA9543A

Datasheet (PDF): http://www.ti.com/litv/pdf/scps206a

 

c)     You can use a GPIO to effectively route SCL to only one of the devices at a time. 

One way to implement this is with an inverter for the control signal and a dual OR gate to route SCL. 

1.     Connect SCL from your processor to one of the inputs of each OR gate, A pull up resistor must be located on this node (2kOhm is ok).

2.     Connect the non-inverted control signal to the other input of the first OR gate. 

3.     Connect the inverted control signal to the other input of the second OR gate. 

4.     Connect the first OR gate's output to SCL on the first gauge(A) and the second OR gate's output to SCL on the second gauge(B).

5.     When the GPIO is high, you will communicate with gauge(A) and when it is low, you will communicate with gauge(B).

 

SN74AUP1G04: Low-Power Single Inverter Gate

Product Folder: http://www.ti.com/product/SN74AUP1G04

Datasheet (PDF): http://www.ti.com/litv/pdf/sces571k

 

SN74AUP1G32: Low-Power Single 2-Input Positive-OR Gate

Product Folder: http://www.ti.com/product/SN74AUP1G32

Datasheet (PDF): http://www.ti.com/litv/pdf/sces580i

 

d) You can also use an SPDT switch to route the SCL signal to each of the devices.  The LVC1G3157 is a great fit for this.

 

SN74LVC1G3157: Single-Pole, Double-Throw Analog Switch

Product Folder: http://www.ti.com/product/SN74LVC1G3157

Datasheet (PDF): http://www.ti.com/lit/gpn/sn74lvc1g3157