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XTR110 and XTR11 Application

Adnan Kurt
Intellectual 665 points
Other Parts Discussed in Thread: XTR111, XTR110

I am willing to use XTR110 or XTR111 for voltage controlled current source (or sink) application in a neurophysiology research application. I have two questions:

1. Is there any Spice model to use under Tina for example?

2. Would there be any chance to add an external circuit to increase the compliance voltage over Vsupply, up to 200V? I would appreciate any advise.

 

Adnan Kurt

  • 0
    TI__Mastermind 27715 points

    Hello Adnan,

    Thank you for your interesting in the XTR110/111 devices, and welcome to the TI E2E forums!

    Unfortunately, no TINA models exist for those devices. However, I would be happy to send you an XTR111 EVM (evaluation module) that you can use to get a feel for the real-world behavior of the part. If you are interested, please e-mail me at ian@ti.com with your shipping address and contact phone number and I'll take care of the rest.

    As for the compliance voltage of the part - it can not be increased above 40-44V (depending on which part you're considering), but you could step down the 200V you have available to something that's more within the XTR's supply range. How that would be done may prove challenging, as to my knowledge there are no 200V-to-40V buck regulators produced by us or any of our competitors, especially ones designed for low power applications. I would suggest posting on the Power Management section of our forums to see if our power experts have a reference design that would be suitable for your needs.

    Alternatively, are there any digital supplies available (5V or 3.3V)? If so, a simple boost converter could easily get you in the range that the XTR needs, especially since the power demands of the device is so small.

    Best regards,

    Ian Williams
    Linear Applications Engineer
    High Performance Linear

  • 0 in reply to Ian Williams
    Intellectual 665 points

    Hi Ian,

    Thanks for fast reply and your kind advise. However sorry for my vague description of the requirements. To clear the question:

    1. I have a low voltage supply rail, 9V indeed. However bones and flesh require higher voltages. That is the reason I ask for high compliance voltage, about 200V. I will use your TPS65573 to get HV. 

    2. Would there be any chance to float the XTR111 above ground and get higher open circuit output voltage? Or would there be solution to control sinking current instead?

    Regards,

    Adnan

  • 0 in reply to Adnan Kurt
    TI__Mastermind 27715 points

    Adnan,

    It is possible to refer to the XTR111 to a voltage above ground, for example, providing +200V to the V_SP pin and connecting the GND pin to +160V so that the potential difference on the part is equal to +40V. However, that presents a new problem - input voltages would have to be level-shifted so that they are referred to the +160V virtual ground, which is possible but difficult.

    Another option is power the XTR111 from the +9V supply you have available, and then connect the "ground" of the load to -200V. This would allow the output voltage developed across the load resistor to meet your compliance requirement of 200V, and the high negative voltage would not be "seen" by the XTR111 so no absolute maximum ratings would be violated. However, you must take care to ensure that  Q1, the p-channel FET which conducts the majority of current, has a breakdown voltage of over 200V.

    At this point I am curious to learn more about your application. Can you describe what your input signal and load driving requirements are?

    Regards,

    Ian