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XTR300: Imon Disconnected

Ryan Hunnicutt
Prodigy 40 points
Part Number: XTR300

When operating the XTR300 in open loop mode, we notice that Icopy does not output to Imon. Please advise how to internally connect Imon to the current mirror in open loop mode.

  • 0
    TI__Mastermind 49455 points

    Hi Ryan,

    Please clarify what is meant by open loop mode.  Does this mean on the externally configured mode with an external feedback network as shown on Figure 4, p9 of the datasheet?  What are the M0, M1 settings?  Please post an schematic.  

    Thank you and Regards,

    Luis

  • 0 in reply to Luis Chioye
    Prodigy 40 points

    Yes by open loop, I mean the externally configured mode. We are applying high logic to both M1 and M2 to configure for external feedback and high current limit. We are not actually applying any feedback network, because our intent is to saturate the DRV pin high or low depending on the state of DAC. When we do this, we find that we cannot read the load current on Imon. Could the saturated op amp be causing some problem with the Imon output switch?

  • 0 in reply to Ryan Hunnicutt
    TI__Mastermind 49455 points

    Hi Ryan,

    The XTR300 is specified to be used within its linear range of operation, with the amplifier configured with either internal or external feedback.

    As you have mentioned, in an open-loop condition, the amplifier output (DRV) will saturate; and the internal current mirror chopper of the current monitor will not work properly. A precision current mirror generates an exact 1/10th copy of the output current using a cycling chopper technique.  The datasheet current monitor section mentions that during the saturation of the DRV output, the error flag is active, and glitches from the current mirror chopper may appear in the current monitor signal, and  the current monitor is not expected to work properly. 

    Thank you and Best Regards,

    Luis