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PGA305: Using OWI for calibration

Dag Daler
Prodigy 60 points
Part Number: PGA305
Other Parts Discussed in Thread: USB2ANY, PGA300

I am designing a load cell, a 4-20 mA loop powered transmitter based upon the PGA305. I want to use the PGA305 GUI during production for device configuration and calibration. Can I interface the USB2ANY card to the sensor current loop without the PGA305EVM evaluation card?

  • 0
    TI__Mastermind 31655 points

    Hello Dag,

    The USB2ANY could be used to communicate directly with a PGA305 through I2C without the need of the EVM, but for OWI communication you will need to use the EVM. There is a significant amount of circuitry used to translate UART signals from the USB2ANY into usable OWI signals, and then back from the PGA305 into UART that the USB2ANY can read.

    Regards,

    Scott

  • 0 in reply to Scott Cummins
    Prodigy 60 points

    Hi Scott, thank you for the answer. When completed the circuitry will be hermetically sealed within the pressure transmitter, only accessible through the 4-20 mA current circuit and I2C is not available. Hence the need for OWI communication. "There is a significant amount of circuitry .." is of little help for me. If you could give some reference to actual circuit designs or design guidelines it would be very helpful.

    Thank you. Regards, Dag

  • 0 in reply to Dag Daler
    TI__Mastermind 31655 points

    Hi Dag,

    The full schematic for the PGA305EVM is available in the user's guide. Specifically figures 18 and 19 contain the information for the OWI signals.

    Regards,
    Scott

  • 0 in reply to Scott Cummins
    Prodigy 60 points

    Hi Scott, I have looked into the PGA300 as an alternative, and I understand that a PGA300 external unit can be interfaced to the GUI by using the PGA300EVM. As such an external PGA300 device can be configured and calibrated using the PGA300 GUI. I would assume that this implies that also the PGA305 can be interfaced using the PGA305EVM for OWI communication. Can you confirm? If yes, can you advice the configuration of the PGA305EVM allowing OWI communication to en external PGA305 device.

  • +1 in reply to Dag Daler
    TI__Mastermind 31655 points

    Yes, the PGA305 can be used with the EVM in the same way. J12 needs to be closed to provide the OWI signals to the VDD pin, and you will connect your external circuit to TP20 (VDD) and Ireturn (TP45). 

    Regards,

    Scott