• State TI Thinks Resolved
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 47 subscribers
  • Views 15 views
  • Users 0 members are here
Support feedback
Options
Options
Related

AMC1301: AMC1301 input problem.

Ahmet Burma
Prodigy 90 points
Part Number: AMC1301
Other Parts Discussed in Thread: AMC1351

Hi guys.

I want to design isolated voltage to 4-20mA converter. I am using MCU with DAC. I designed the schematic using AMC1301 and XTR11.

AMC.png

DAC value max ==> 3.3V. Circuit if working fine. But i have a little bit problem. The voltage required at the INP input of the AMC is as follows; 

If the DAC is 1V ==> INP = (1/(R63 + R70) * R70) = (1 / 6630) * 510 = 0.07692V

However, I'm measuring a higher voltage, around 0.089, at the AMC's INP input. The resistors have a 0.1% tolerance and are accurate. Any idea why this might be?

Best regards.

  • 0
    TI__Expert 6260 points

    Hi Ahmet,

    Can you provide some more information on your application? 

    This device is intended for current sensing applications, measuring across a low impedance shunt resistor.  The input current of the device is about 30uA, which would cause a ~15mV offset.  You can account for this offset by doing an offset calibration of your system and/or reducing the R63/R70 resistance.

    I would recommend moving to a device with higher input range that is intended for voltage sensing such the AMC0311 or AMC1351.

    Thanks.