• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 389 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

DAC161S997: How to connect the HART modem

DAC161S997: HART using DAC161S997

Meir Ifrah
Prodigy 20 points
Part Number: DAC161S997

On "DAC161S997: How to connect the HART modem" there is a 49.9 ohm resistor connected to 6800pF and ground.

Is it necessary for the design?

On slaa572.pdf page 3 there are values of resistors for calculating the HPF, what are the values of the resistors in the DAC161S997?

 

Thnak you and have a nice day,

Meir

 

 

  • 0
    TI__Mastermind 46290 points

    Meir,

    I have not tested the circuit without the 49.9 ohm resistor as is included on the EVM but I do know that the circuit on the EVM meets the HART requirements, so my suggestion would be to stick to that to have a pain-free experience.

  • 0 in reply to Kevin Duke
    Prodigy 20 points

    Hi,

    Somehow the 4-20mA value is 0 when the resistor installed.

    Without the resistor the 4-20mA works.

    Although what are the resistors values in the DAC?

    Thank you  

  • 0 in reply to Meir Ifrah
    TI__Mastermind 46290 points

    Meir,

    Figure 20 on page 23 of the datasheet illustrates the values for the resistors in between each C1, C2, and C3 nodes as well as the values for the gain setting resistors. I'm not deeply familiar with the process technology used for this device, I would anticipate that most of the effort is around ratiometric matching as opposed to absolute value tolerances so most likely these are 10-20% tolerant.

    I am not sure how R11 could have any impact on the DC operating conditions of the DAC. There is a DC-blocking capacitor in between R11 and the C2 node.