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power supply for ads1605evm

Simone Piccirilli
Prodigy 230 points

Other Parts Discussed in Thread: ADS1605, ADS1606

Hello,

I'm trying to interface an ads1605evm with a xilinx board. Using a bench power supply, I apply a 12 V as reference voltage to the board (it shoud be between 8 and 40 V). Following the user guide instruction, I setted all the jumpers and dip switch for the external reference mode. At this point I see that there isn't current absorption (the bench power supply amperemeter signs 0). Another problem is that all the IC on the board have a reference voltage around 1 V or less. So I'm not understanding if I'm making a mistake or there is some problem on the board.

Any suggestion?

Thanks!!!

Ciao

Simone Piccirilli

  • 0
    TI__Guru**** 182721 points

    Hi Simone,

    The external reference is only needed if you choose not to use the internal reference source.  Please review page 19 and section 3-1 of the Users Guide.  You need a bipolar +/-5V supply for the analog section of the board, you also need 5V to power the analog and digital I/O sections of the ADS1605 as well as a 3.0-3.3V digital core voltage.  Once you have all of these supplies attached to the board, you can go ahead with the external reference as well.

  • 0 in reply to Tom Hendrick
    Prodigy 230 points

    OMG! I misunderstood something... I hope to have read better the other parts of user guide! :D

    Many thanks for your useful help!

    Cia

    Simone Piccirilli

  • 0 in reply to Tom Hendrick
    Prodigy 230 points

    Hi  Tom,

    I've a question about the connector J4/P4 for power supply. On page 19, table 3-1, the Analog GND  (AGND) is assigned to pin 5, while on schematic, at page 50, AGND is assigned to pin 6. What is the right pin assignment? And what are the differences between them? I mean,if Iswap AGND with DGND, is it the same or will I have troubles?

    Also, watching table 1-2 and table 2-1 it seems to be opposite assignment for the external reference selection. I think that table 2-1 is right, but I`m not sure.

    Thanks for  your help.

    Cia

    Simone

  • 0 in reply to Simone Piccirilli
    TI__Guru**** 182721 points

    Hi Simone,

    Pins 5/6 of J4/P4 are technically shorted together through R34, so it really should not matter.  By the schematic at the back of the Users Guide, pin 6 is AGND so we'll take a look into Table 3-1.  For the reference, by the schematic on pg 44, the source is pin 2 and ground (ref return) is pin 1.  that matches the tracking layer shown on page 40.  Pin 1 is the square pad, pin 2 is the round pad.  REFEN = 0 enables the internal reference of the ADS1605, this signal is actually a control leading to pin 13 of the ADS1606 - its not connected directly to the external reference circuit.