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ADS1015-Q1: Need Info on I2C and Alert Connection

khemraj suthar
Intellectual 836 points
Part Number: ADS1015-Q1

Tool/software:

Hello TI Team,

We want to use ADS1015-Q1 in our design and have following queries:

1. I2C, Alert pins are open drain output can we connect it to 3.3V pull up and keep VDD as 5V?

2. Our analog input range is from 0V to 5V input. In this case we need to connect 5V on the VDD pin. Can you please confirm if we are going to have any problem in our design if we use digital part at 3.3V and analog part with 5V. 

3. Below is the screenshot of the plan how we are planning to connect this. Can you please confirm if this looks fine

Your immediate response on this would be highly appreciated.

Regards,

Khemraj Suthar

  • 0
    TI__Guru 51666 points

    Hi khmeraj suthar,

    Today is a national holiday in the US, please expect an initial response to your post in the next 1-2 days. Thanks for your patience.

    -Bryan

  • 0
    TI__Prodigy 570 points

    Hello Khemraj Suthar, 

    If the ALERT/RDY output pin is not used, leave the pin unconnected or tie the pin to VDD using a weak pullup resistor.

    The ADS1015-Q1 has digital input levels that are ratiometric to VDD. Using a 5V VDD the 3.3V digital levels do not satisfy the requirement of VIHmin = 0.7 * VDD (0.7 * 5 = 3.5V).

    3.3V would not register as a logic '1' since it would fall below the VIHmin threshold. 

    If the digital supply must remain at VDD = 3.3V you can use an I2C level translator between the ADS1015-Q1 and the Host Soc. The TCA9517-Q1 or TCA39306-Q1 could be good options for a translator. 

    Regards, 

    Andrew