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ADAS3022 Recommended Circuit Help

I see in the Recommended circuit schematic for the ADAS3022 ADC that the ADR434 is to be used for providing the 4.096 V reference voltage. When I considered the ADR434 datasheet, I see that it is meant to operate at a voltage from 6V-18V. The Recommended circuit for the ADAS3022 designates that a 5V input should be given to the ADR434. Is this correct? If not, how can the circuit be adjusted to consider this? Any assistance would be appreciated.

  • Hi codigwe,

    True ADR434  operate to a range of 6.1V to 18V. However the evaluation board ADR434  used Vin= +15V. Please see attached picture,seems we need to update figure53  of the datasheet to avoid this confusion. Thanks for catching this.For more information you can check the whole schematic in the  user guide UG484.

    regards,

    LLoben

  • Hi codigwe,

    I'd like to ask if you are using the evaluation board or you have your own circuit diagram, if so can you share the schematic.

    regards,

    Lloben

  • Dear LLoben,

    Thank you very much for your reply. Would this mean that I should be able to power the ADR434 with the +15 V rail and keep all of the other connections in the recommended circuit the same? I have tried this, and I am experiencing strange behavior with the circuit drawing up to 200 mA in current without the ADAS3022 being operational. Please let me know of any changes that can correct this problem.

  • Dear Lloben,

    I am using the ADAS3022 to send data to a Teensy 3.2 using the same connections in the ADAS3022 recommended circuit with the circuit attached below. Should any changes be made to correct this problem? Thank you for your help.

  • Hi codigwe,

    Seems you follow the recommended setting for the reference circuit.It should be able to power the ADR435 with a  +15V supply. . Aside from ADAS3022 and ADR435 what other components connected to this? it draw current if the total impedance excess  than  expected. I should check first the  power supply circuit.Try to limit the connection on this. Please take note ADP1612/13 as per datasheet page3 Vout=12V  ILoad is limited to 10mA to 150mA.

    regards,

    LLoben

  • Hi codigwe,

    I'm glad to hear that it works.Yes circuit still works. ADAS3022 allows the choice of an  internal reference. Please take note in using decoupling capacitor as shown in datasheet figure62 to reduce the noise on the output.

    regards,

    Lloben

  • Dear LLoben,

    Thank you for your reply! I currently have a Teensy 3.2 connected to the +5V rail. After looking over the circuit again, I was able to find a simple mistake I made where pads on two of the coupled inductors were incorrectly labeled in my schematic. After fixing that error, the current that the circuit draws has now dropped to about 75 mA with the ADAS3022 not in operation. I appreciate your help! One last question: Would this recommended circuit allow for operation if I were exclude the ADR434 and AD8031 and use the internal 4.096 V reference voltage instead?

  • Dear Lloben,

    Thank you very much for all of your help! It means a lot. 

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