XTR111-2EVM: Signal not stable.

Hi CS,

Can you share more information regarding power supply voltage, signal input, output requirements, and how you've configured the jumpers (J1, J2, J3)?

Did you follow the EVM setup instructions in the guide? http://www.ti.com/lit/ug/sbou048c/sbou048c.pdf See Figure 3 for "Voltage Output Setup"

-Tamara

Hi Tamara,

I use a bench top power supply, supply 24Vdc. Then from the EVM board tap the 5V to a trim pot of 10K to send the signal to get 12mA output, measure from a bench multimeter.

Did not use any of the jumpers, open.

Look like there a small ac wave sitting on the DC. I use a load of 250 ohm. 

Anyway to make this wave smaller?

Regards

CS

Hi CS,

One note on the jumpers, for voltage output mode J2 needs to be installed. Please refer to the jumper table and figure 3 of the user's guide:

-Tamara

Hi Tamara,

I need the output to be 4-20mA.

Why I need to change to voltage output?

Regards

CS

Hi CS,

My apologies, I mis-read your initial post. You're right, all jumpers should be open. 

As you vary the pot, can you measure the min and max voltage at VIN? A test point connected to VIN is located next to TB4. I want to make sure the input voltage is within spec range. 

Can you also try disconnecting the pot and just applying a DC voltage of 0-5V to the input VIN at TB4 and measuring the output IOUT at TB2? If the issue persists, we may want to try another XTR111 device. If the output is as expected, then there may be a problem with the pot.

-Tamara