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AD74115H questions

Category: Hardware


I'm planning using the AD74115H combo DAC/ADC but after reading the datasheet, I have simple questions that have no obvious answers :

  • Can it be used as independent regular ADC and DAC (voltage modes only, with no power, no current at all, no "screw terminal " stuff) ? The datasheet never suggest this, there is always some link between them in any case because only specific uses are covered with all sorts of sense lines which are not used at all in a "standard" use.
  • If this can be used has separate ADC and DACs, which inputs and outputs are used ? For the ADC, i suppose that the SENSELF and AGND can be used as single ended inputs, but it is not that clear for the DAC : is it between  VIOUT and AGND?  Is the SENSEH pin has to be used?  Where the CCOMP should be placed?
  • If the Hart modem is not used, how the pins should be connected ?
  • if the "digital" part is not used, how the related pins are connected (external MOSFETS, DO_VDD...)?

Thanks in advance,


  • Hi Jerome,

    thank you for your questions.

    "Can it be used as independent regular ADC and DAC..." - Could you please clarify your application, I would like to understand, what you mean by "standard" use. This part is meant to be Software Configurable Input Output, which gives user flexibility to switch any of the defined operation modes on the fly. For this reason, the design architecture is so specific, which combines ability to bring DAC and ADC to same pins (screw terminals).

    "If this can be used has separate ADC and DACs, which inputs and outputs are used ?..." - ADC MUX settings are available at "Table 23. Selection Options for ADC Conversion 1" and "Table 24. Selection Options for ADC Conversion 2", these settings specify which pins are connected to ADC inputs. DAC is using SENSEH and SENSEL pins for it's operation (in case of current output). Single ended DAC (Voltage output mode) is using SENSEL pin. CCOMP should be place at the point of the "SENSEL" pin for compensation purposes. However it looks to me, that you might want to use the part differently, than it was characterised.

    "If the Hart modem is not used, how the pins should be connected ?" - I am going to double check the connection of the HART pins, when they are not in use. If you don't indent to use HART, you might be interested to AD74115 (version without HART), which is going to be released by the end of this year.

    "if the "digital" part is not used, how the related pins are connected (external MOSFETS, DO_VDD...)?" - Please let me double check on DO pins, when DO function is not used.



  • Hello,

    Thank you for your answer.

    My goal is very simple, using this combo ADC+DAC as if I've bought two separate chips but with the advantage of using one SPI and one chip. and the 12V input/output capabilities are perfect for me.

    So, I would like to know how to wire this chip (if possible) to have a single ended input 0-12V to the ADC and a single ended output 0-12V for the DAC without interaction between the two (except sharing the same analog ground). That's all.

    You seem to underestimate the advantage of having these two quite high resolution DAC/ADC in one chip without even considering all these bells and whistles Grin. It was the only one I could find, so this part could be very interesting for a more "regular" use. I could see from the block description that it Is actually possible, but I'm always afraid of stuff that is not said that could interfere, even prevent from functioning.

    I need currently available parts, so I prefer this one with the modem even though I don't use it.


  • Hi Jerome,

    thank you for your inputs. Its great, that you are going to use AD74115H in your application and I am happy it meet your needs.

    To answer your question on unused pins of DO module and HART module, please connect pins as follows:

    DO_VDD:                           This should be tied to an existing supply. Avcc will be ok, or Avdd

    DO_SRC_DGATE:             Leave this float,

    DO_SRC_GATE:                Leave this float

    DO_SRC_SNS:                  Tie this to the same pin as DO_VDD

    DO_SRC_INT:                    Leave this float 

    DO_SNK_SNS:                   Tie this to gnd

    DO_SNK_SNS                    Leave this float

    DO_SNK_GATE                 Leave this float

    HART_TX_IN                     Leave this float

    HART_TX_OUT                 Leave this float

    HART_RX                          Leave this float

    Please let me know, if I have answered all your questions.

    If you have further queries, don't hesitate to contact me.



  • Hello,

    Many, many thanks for this, I wouldn't have guess some data given there. I join the way I would use this chip. I create power rails with its ADP1034 companion chip.

    Are ADC input (IN_LF) and DAC output correct, given that the OUT and OUT_SENSE ports are linked together somewhere ?

    Again, thank you !


  • Hi Jerome,

    based on my understanding of your schematic, I can confirm, that ADC IN_LF should work as single ended ADC input and DAC OUT and OUT_SENSE as single ended Voltage output.



  • Great, I can make the prototype now...

    Thanks for all,


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