Hello,
I am using XTR117 in one of the Product as 4-20mA loop transmitter and I have seen couple of failure which had High impedance between the Iret and IO pin.(typical resistance between these pins should be around 30 ohms)
We do have a reverse voltage protection & TVS diode to protect it from the Over voltage.
What are all other factors which leads to this failure.
thanks,
Raghavendra
Hi Raghavendra,
The XTR117 device must not be exposed to over-currents and over-voltages above the Absolute Maximum Ratings as shown on page 2 of the device datasheet to avoid permanent damage.
The "2-wire 4-20mA Transmitter, EMC/EMI Reference Design" TIPD190 incorporates a device from the same family, the XTR116, (the XTR116 has the same design architecture as XTR117, adds a voltage reference).
The Reference Design schematic includes a robust output protection circuit for IEC61000-4 immunity and a bridge rectifier to enable functionality regardless of the polarity of loop supply connections. The protection circuit example is shown on section 2.3 of the reference design user guide, it includes a bidirectional TVS diode, series ferrite beads on the loop supply connections, a bypass capacitor and a diode switching bridge to protect against incorrect wire faults.
The reference design was tested to IEC61000 standards and results are shown in the report. You may refer to the schematic, bill of materials and board layout design files as an example for recommended protection.
Thank you and Regards,
Luis
