AD5593R - Protection of Multifunction IOs

How can I protect the multifunction IOs of the AD5593R, when it is unpowered?

The datasheet states: "Analog Input Voltage to GND: −0.3 V to VDD + 0.3 V".

Can you provide an absolute maximum specification for the pin current, such that protection by a resistor becomes possible?

  • Hello ADI,

    is this forum still active?

    Kind regards,

     

    Dipl.-Ing. Sven Probst.

     

     

    # --------------------------------------------------------------------------
    # EdgeWave GmbH
    # Dipl.-Ing. Sven Probst
    # Carlo-Schmid-Str. 19

    # D-52146 Wuerselen, Germany
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  • 0
    •  Analog Employees 
    on Apr 19, 2018 12:32 PM

    Hi,

    Apologies for the late response. Someone is looking into this thread and will respond to you as soon as possible.

    Would like to get more information about your query, when you say "unpowered", is VDD shorted to ground or at high-impedance? 

    Cheers.

    Ivan

  • Hi Ivan,

    it is difficult to say how the other components on the VDD net will behave. For very low voltages (a few 100mV) of VDD it will be 22k to GND (inside DC/DC-Converter). At least for voltages higher than about 2V there will be an LED consuming some mA.

    See the attachment for the details of the schematic. The yellow marked inputs we are dealing with. Maximum voltage is 2.5V.

    Kind regards,

    Sven.

  • 0
    •  Analog Employees 
    on Apr 20, 2018 1:25 PM

    Hi,

    When the Device is not powered or underpowered( VDD< 2.7V) i would not suggest providing any voltage at the terminal.

    Please sequence the power supply such that Ad5593R is powered before applying any voltage on the IOx terminals.

    Regards,

    Koushik 

  • Hi Koushik,

    such a power sequencing is impossible in the given case, because the module providing the signals is supplied by another supply and this module is not going to be redesigned.

    Obviously the device contains clamping diodes to GND and VDD, and there must be information about the current they can carry (as given for many other devices from AD).

    Please ask the development people about this current. In my case the input current is limited to 250µA per pin. Honestly, this cannot be too much for an ESD device.

    If you cannot provide this number, I have to choose another device / manufacturer, because there are space constraints not allowing many additional components.

    Kind regards,

     

    Dipl.-Ing. Sven Probst.

     

    # --------------------------------------------------------------------------
    # EdgeWave GmbH
    # Dipl.-Ing. Sven Probst
    # Carlo-Schmid-Str. 19

    # D-52146 Wuerselen, Germany
    # --------------------------------------------------------------------------