Part recommendation to have more than four I2C devices with 2 bits address

Jason Song

Other Parts Discussed in Thread: TCA9548A

Hi TIer,

Our application requires us to use four I2C matrix switches (ADG728BRUZ), but now we have to expand the channels, so we would need eight ADG728BRUZ. I read the app note (SCAA137), and from my understanding, the easiest way to achieve this is to use I2C switch, do you have any part recommendation that would allow eight of those 2 bits I2C devices?

In addition, does TI has any I2C controlled matrix switches similar to ADG728BRUZ?

Thank you,

Jason

over 4 years ago

0 Bryan Marshall over 4 years ago

TI__Genius 10974 points

Hi Jason,

I believe this is the same inquiry you had from yesterday:

https://e2e.ti.com/support/switches-multiplexers-group/switches-multiplexers/f/switches-multiplexers-forum/1036034/ti-equivalent-solution-for-adg728bruz/3831795#3831795

As I mentioned there, TI does not have any I2C controlled switches available in our portfolio. Please see the solution I mentioned in the above thread for best possible alternative to this.

Thanks,

Bryan

0 Jason Song over 4 years ago in reply to Bryan Marshall

Prodigy 100 points

Hi Bryan,

I understands TI does not have i2c MUX, but this question is actually about the i2c bus switch.

https://www.ti.com/interface/i2c/switches-and-multiplexers/products.html

I am trying to use one of them to solve the problem and would you be able to suggest one of those switches for my application?

Thank you,

Jason

0 Jason Song over 4 years ago in reply to Jason Song

Prodigy 100 points

Hi Bryan,

I am planning to add the TCA9548A 8 channel I2C bus switch. I know the IC is designed to drive one I2C device from each of the 8 channels, but to reduce the complexity, I wonder if I can have four I2C addresses connected to for example SC0 and SD0; and another group of four to SC1 and SD1. Can we do that? Any concerns?

Thank you,
Jason

0 Eric Hackett over 4 years ago in reply to Jason Song

TI__Guru 74282 points

Jason,

I've notified our I2C expert of this thread. Thank you for your patience.

Regards,

Eric Hackett

0 Jason Song over 4 years ago in reply to Eric Hackett

Prodigy 100 points

Thank you, and I am looking forward to getting the answer from TI I2C expert.

0 BOBBY over 4 years ago in reply to Jason Song

TI__Guru 73651 points

Hey Jason,

Can't you use the TCA9548A? This is an 8 channel I2C switch that has 3 addressable hardware pins meaning it can support 8 TCA9548As in parallel.

-Bobby

0 Jason Song over 4 years ago in reply to BOBBY

Prodigy 100 points

Hi Bobby,

Yes, we plan to use TCA9548A, but instead of having single address on the 8 I2C devices. Can we have multiple groups of I2C devices on each of the 8 channels of the TCA9548A? In each of the group, we will have four I2C devices with four different addresses. Will this work?

Thank you,
Jason

+1 BOBBY over 4 years ago in reply to Jason Song

TI__Guru 73651 points

Hi Jason,

If each of the addresses are unique per channel of the TCA9548A and you only enable one channel on the TCA9548A at a time then I don't see a problem.

I'm assuming you mean:

---------------------------------------first TCA9548A---------------------------------------

|TCA9548A|-CH1 <4x devices with unique address>

|TCA9548A|-CH2 <4x devices with unique address>

|TCA9548A|-CH3 <4x devices with unique address>

|TCA9548A|-CH4 <4x devices with unique address>

|TCA9548A|-CH5 <4x devices with unique address>

|TCA9548A|-CH6 <4x devices with unique address>

|TCA9548A|-CH7 <4x devices with unique address>

|TCA9548A|-CH8 <4x devices with unique address>

---^-second TCA9548A parallel to first and unique address to first---------

|TCA9548A|-CH1 <4x devices with unique address>

|TCA9548A|-CH2 <4x devices with unique address>

|TCA9548A|-CH3 <4x devices with unique address>

|TCA9548A|-CH4 <4x devices with unique address>

|TCA9548A|-CH5 <4x devices with unique address>

|TCA9548A|-CH6 <4x devices with unique address>

|TCA9548A|-CH7 <4x devices with unique address>

|TCA9548A|-CH8 <4x devices with unique address>

------------------ect.---------------------------------------------------------------------

From here, you would never enable more than one channel of any TCA9548A at a time.

-Bobby

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Part recommendation to have more than four I2C devices with 2 bits address