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XTR115: XTR115 IO and IRET pins shorted

Muhammad Naeem1
Prodigy 50 points
Part Number: XTR115
Other Parts Discussed in Thread: XTR111, XTR300

Hi,

I was wondering if I can get some advice on the circuit below. In our current loop design, there is a possibility that the 0VDC (IO) on the current loop supply will be shorted with IRET (0V of our internal circuit, potential earth).  

In our design, internal 0V is connected to earth and in situations when it is not possible to source an isolated 24VDC supply, the IO PIN (0 VDC) on the current loop supply will be shorted with IRET PIN (0V of our internal circuit). When IO and IRET are shorted, this leads to a problem on the current loop as the XTR115 saturates to 25 mA (as the internal R2 resistor is shorted).

I was wondering if there is a potential work around when XTR115 is used in this configuration (we can modify the circuit) or there is an IC based solution available from TI.

Thanks in advance.

  • 0
    TI__Mastermind 23050 points
    Hi Muhammad,

    You cannot short the IRET pin to the same ground as your supply voltage and unfortunately there isn't really a work around for this. If isolation is not possible, then you would need to use a 3-wire device, such as the XTR111 or XTR300.