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XTR305: Output current limit

Kuramochi Tadahiko
Guru 28715 points
Part Number: XTR305

Hi,

I recognize that XTR305 has output current limit function.

However, it is recommended to add external protection on the datasheet, "8.2.2.10 Output Protection".

I think that external protection is not necessary if internal protection works well. 

What case is internal protection insufficient?

Best Regards,

Kuramochi

  • 0
    Guru 140200 points

    Hi Kuramochi,

    the protection circuitry shown in figure 46 protects the output of XTR305, if the output is hit by voltages exceeding the supply rails.

    Kai

  • 0 in reply to kai klaas69
    Guru 28715 points

    Hi Kai,

    I had assumed that the load is low impedance.

    In the case, is the resistor limiting current unnecessary?

    Best Regards,

    Kuramochi

  • 0 in reply to Kuramochi Tadahiko
    TI__Guru 55466 points

    HI Kuramochi,

    The protection circuit in figure 46 is to ensure that the output voltage at the device output does not exceed the voltage supplies or the Absolute Maximum Ratings of table 6.1.

    The XTR305 can deliver amaximum of +/- 24mA (or +/-38.5mA) in current output mode within the allowed output voltage range (V-) +3V and (V+) -3V . However, in a fault condition, where the XTR305 output is shorted and the output voltage exceeds the supplies, the external resistor and external diodes of Figure 46 will limit the output voltage to ensure that the current flowing through the XTR305 internal protection diodes does not exceed 50mA permanently damaging the device.

    The current limit of the device is +/-38.5mA with M2=High, and +/-24mA with M2=Low.  In Current output mode, the Load Error flag indicates saturation into the supply rails due to high load resistance or open load.

    Best Regards,

    Luis