Reg: ADC (ADAS3023BCPZ) not working

Hi,

I am using ADC IC (ADAS3023BCPZ) which is working for only 20 to 30 minutes; after that it gets heated-up by drawing more current from the supply.

Used Supply details - 

VDDH -> +15V ; VSSH -> -15V ; AVDD,DVDD -> +5V ; VIO -> 3.3V

Only difference in schematic with respect to datasheet is - EP(Exposed Pad) is connected to AGND in my board instead of VSSH.

Is this the reason for heating-up the IC after some minutes ?

Please clarify on this point.

Thanks,

Tusarkanta Das

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    •  Analog Employees 
    on Jan 10, 2019 1:58 AM over 1 year ago in reply to Tusar@Delta

    Hi Tusar,

    Apology for taking late response. I have to check few things just to confirm.

    1. This should be corrected. the exposed paddle MUST be connected to VSSH as this is the lowest potential in the circuit and  avoid permanent damaged to the device.

    2. From your schematic PD(digital inputs) is not connected. This should be tied low. Can you check to see the voltage at ACAP(26)and DCAP(25). If these are not approximately 2.5V to 2.6V then it indicates the ADC may be in shutdown mode.

    3. Since you are using the internal reference can you verify the voltages.

    4. additionally we would recommend

               a. 100K weak pull up to 3.3V supply rail to CS,CNV and RESET pins.

               b. 100K to DGND to PD at a minimum or I would however prefer to add the isolated driver for PD and  a weak pull up to 3.3V supply as well.

    If you could provide a PDF of the supply decoupling and connectivity for the ADAS3023 it would be helpful.

    It would also be helpful to see the power up sequence scope shots.

    Finally a scope shots of the digital activity for the first conversion and subsequent conversions would be very helpful as well.

    Thanks and Best regards,

    LLoben

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