In my desgin, Vibration Sesor has x ,y ,z ,temperature voltage outputs respectively.
Using 4 pieces XTR117 to conver the four channel voltage , the block diagram is listed below :
1. using the first XTR117 Vreg pin to power the sensor , is it ok ?
2. Can I connect four Iret pins together ? If not ,how to do ?
Thank you
Hello,
Could you upload a higher resolution image of the block diagram?
1. using the first XTR117 Vreg pin to power the sensor , is it ok ?
5Vdc or Vreg with respect to Iret has current sourcing limit. Vreg has to source low power 5Vdc load, and current has to be limited to 3 to 3.75mA range. And the Vreg voltage droop is shown in the graph below. Yes, it can drive it, but the total aggregated current internal to each XTR117 has to be less than 3.75mA @5Vdc, when there are no input signals present.
2. Can I connect four Iret pins together ? If not ,how to do ?
You can not connect all Iret pin together. Each current branch to Iret has to be treated separately, and Iret is a floating node independently.
Below is a simulation example, where input is from 0V to 3V and output is 4-20mA, and Rload = 500ohm (to convert the Iout back to voltage).
XTR117 0-2V to 4-20mA 03312024.TSC
If you have other questions, please let me know.
Alternatively, you may have to use XTR111 for the application.
Best,
Raymond
Hello,
Do I need three pieces of XTR117 ?
Based on the initial schematic diagram, you have X, Y and Z axis for sensing. Yes, you will need to have 3 individual XTR117 voltage to 4-20mA current conversion ICs.
how to resolve the sensor chip power supply ?
If your sensor is low power type and is able to be powered with 5V@ <3.7mA, then the 5Vreg will be able to drive it.
If the sensor current consumes more than 3.7mA @5Vdc from the onboard Vreg, then we need find alternative ways to do the voltage to 4-20mA current conversion.
Can I use a dependent 5V power supply other than the VREG of XTR117
You may not be able to design the circuit with XTR117 (2-wire current loop transmitter), since the different 5Vdc also have to be reference to Iret pin.
You are able to do with XTR111 transmitter, which this is called 3-wire current loop transmitter, and the sensor's PS can drive the sensing current to GND. You can use separate 5Vdc PS to drive the sensor and tied all the GND together.
This is 2-wire transmitter in XTR117 example, where Iret node has to be floating.
This is 3-wire transmitter in XTR111 example.
XTR111_0-3V_to_4-20mA 04112024.TSC
Please let me know if you need further assistant.
Best,
Raymond
