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ADC081C027: I2C ADC with many addresses

Dan Rechichi
Prodigy 10 points
Part Number: ADC081C027
Other Parts Discussed in Thread: ADS122C04, TLA2528, ADC081C021, ADS1119

Tool/software:

Hi,

Is there an I2C based ADC that can support around 20 or more I2C addresses?
I'm trying to implement a self test feature on a board using TMP1075DSGR for temperature and some ADC.

TMP1075DSGR can support 32 addresses which makes it possible for me to use point of load topology.
However every ADC I've looked at is capped at 9 addresses. Most of them at 4.

Ideally I would be able to find a 1 channel ADC that is in a small package, and can support 32 addressers to match the temperature sensor.
But I could also make a4 channel ADC work if it can support at least 16 addresses and is still a small package.

It's just for measuring voltage supplies.
Speed is not a factor.
Resolution is also barely a factor since I only care if my voltages are within a 5% tolerance, measured through dividers.

  • 0
    TI__Expert 6090 points

    Hi Dan,

    I don't believe we have any ADCs that support that many I2C addresses. 

    We do have the ADS122C04, which is a 24-Bit, 4-Channel ADC with 16 I2C addresses. Since your requirements are low resolution though, I'm not sure if this would be suitable.

    Another offering is the TLA2528, which is a 12-bit, 8-channel ADC with 8 I2C addresses. 

    This ADC081C021 (VSSOP-8 package) as you said does have 9 addresses.

    I am interested in your use case however. Can you explain more on why you would prefer a single-channel ADC with lots of I2C addresses over a MUXed multichannel option?

    Regards,
    Joel

  • 0 in reply to Joel Meraz
    Prodigy 10 points

    Thanks Joel,

    I think TLA2528 might be the best option for now. Sorry about the delayed response.

    Additional application info:

    I think a point of load offering would be incredibly valuable. Similar to point of load power where the regulator is placed at the load for minimised inductance/resistance, and improved remote sensing. However, the other benefit is that this significantly reduces the number of power planes needed since more power rails have less distance to travel, unless some rails are needed in multiple locations and can follow point of load topology.

    In the case of the ADC, having a single channel option that can have 32 or more addresses, would mean only having to route an I2C bus around the board, instead of multiple ADC lines. This is extremely helpful when trying to reduce the number of signal layers, or when trying to make better use of signal layers when routing many differential pairs, or high speed signals, or other things.

    In my specific case, I have 3 PCBs in a stack, with 2 of those directly hanging off the base board. Routing a single I2C bus between boards is much easier than having to route many ADC lines. The I2C bus consumes significantly less pins on the board to board connectors. This makes placement planning much easier for me, and gives back some much needed Z axis space to the mechanical team. Alternatively, if the mech team is happy and if I have the room, I just get more pins for other things.

    Being able to drop an ADC wherever it's needed massively improves the system architecture for the multi-board project, but also the floor planning and the layer stack and routing efficiency of the individual boards. I also like applying point of load topology to TMP1075 for temperature sensing.

    Kind regards,
    Dan

  • 0 in reply to Dan Rechichi
    TI__Expert 6090 points

    Hi Dan,

    Thanks for the information!

    You might also chose to take a look at the ADS1119, which is a 16-bit, 4-channel ADC with 16 I2C addresses. 

    Regards,
    Joel