AD623 Issues

Hi, I am using AD623 as a current to voltage converter by using a shunt resistor. The supply rail is 5V, the gain is set to 1 (Rg  pins open).

The voltage output follows the input voltage across the shunt till a value of about 4.7V and after that it jumps directly to 5V . What could be the reason. i have also tried connecting the return line of the shunt to the IC ground line with same effect.

Another issue is that many of these ICs are failing after some time. Can there be issues with spikes generated when the sensor which is producing the current input starts up. I had this issue with Texas Inst Amps because of which I shifted the design to AD623.

  • 0
    •  Analog Employees 
    on Apr 19, 2015 8:09 PM

    Hi Narayan,

    Thank you for using ADI products on your applications. Can you tell me more about your applications? Are you using 5V single supply voltage for the AD623? Where is the current coming from? What is the expected current flowing in the shunt? What is the value of the shunt? What is the maximum current spikes present on the sensor during start up? It is important to limit the input voltage and not to exceed 0.3 V above the supply rail. Please see the discussion on INPUT PROTECTION section on page 17 of its datasheets. A series resistor is needed if overvoltage is expected on the input and input current should be limited to about 10 mA.

    Do you have a potential on the referece pin? It would help if you could share your schematic here.

    Please see the input voltage range of the AD623. If you are trying to input a 4.7 V in a 5 V supply rail then I would say that you are violating the IVR of the device as shown below.

    Do you able to consider to use a current sense amplifier instead of an Inamp for this type of application?

    Best regards,

    Emman

  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:00 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin