• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 30 subscribers
  • Views 951 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

EK-TM4C123GXL: EK-TM4C123GXL: ADC input impedance

jsuarezbaron
Prodigy 40 points
Part Number: EK-TM4C123GXL


Hi everyone.

I working with a Tiva C 123 (TM4C123GH6PMI MCU). My application goal is read the analog value of a pressure sensor (0.5V-4.9V, output voltage). Thinking about in some measurement errors, e.g. If the source is low-impedance and the ADC is high-impedance, one could lower the value of the voltage divider, e.g. 1.7k:3.3k. This might introduce some measurement errors, e.g. if the the ADC input has a large capacity on the input and hence the inrush current during the sampling period might lead to a voltage drop. In this case I want to know if the input impedance of the TM4C123GH6PMI MCU ADC channels is high and his value, but I did not found it in the datasheet. n which section of the datasheet this information appear?


Thanks.

Best regards.

  • 0
    TI__Guru**** 183956 points

    hi,

     We document the internal Radc and other parameters in the datasheet electrical section. See below.  Please also refer to the TM4C123 System Designs Guideline for recommendation on the external source resistance when using the voltage divider. Basically you want to keep resistance from ADC input to the ground low. www.ti.com/.../spma059.pdf.