Part Number: TPS60402
We built the circuit as Figure 4: Input-sensor-isolated 2-wire transmitter from following link
But we are facing following issue.
when we check 4 to 20 mA output, we find 12 mA by default instead of 4 mA.
But when we disconnect input supply of TPS60402, default output is 4 mA. But we need this output by supplying to TPS60402.
How to fix this issue ?
following is the sch. for reference.
It sounds like you're returning too much current back to the transmitter which is preventing you from reaching the desired minimum 4mA level.
What type of load do you have on the output of the LDO on the secondary side? You won't be able to return more than ~3.5mA back into the "IRET" pin of the XTR116 while being able to achieve the 4mA zero-scale level.
Regards,Collin WellsGeneral Purpose Amplifier Applications
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In reply to Collin Wells:
In reply to shashikant jadhav:
The current through the transformer on the primary side returns to the IRET pin, along with the quiescent current of the TPS60402, the currents of the digital isolator and any other circuitry powered from the VREG output of the XTR116.
Depending on how you're operating the TPS60402 and what type of efficiency it's achieving you'll likely not be able to consume more than 1-2mA on the secondary side.
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