Potentiostat / Amperometric Measurement Using ADuCM350

Document created by LiamR Employee on Apr 25, 2014Last modified by LiamR Employee on Nov 13, 2015
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System Setup

  • Documentation:
    • AN-1281
  • Hardware
    • Eval-ADuCM350EBZ
    • ADuCM350 Switch Mux Config
  • Software
    • AmperometricMeasurement example in IAR Embedded Workbench
  • View data in Comms port

     Picture1.bmp

Software Configuration for measuring R5 + R6 (10uF + 6.8 kOhm)

Black Text Is Original

Red Text is changes from Original

Picture2.bmp

 

Validate Results of Setup

 

  • Change Switch Matrix so that you measure the 2 kOhm + 6.8 kOhm on ADuCM350 Switch Mux Config Board (AFE 4 to AFE 6).
  • Delay after switch mux not required to be significant as switches only see resistors.

Picture3.bmp

 

Results for measuring 2K + 6.8K

 

  • Results on Serial Comms Terminal
  • Code starts at 32768 (DC Level 1 = 0 V = Midscale)
  • Code Settles at 25790 (DC Level 2 = 300mV)


Putty Pic.png

 

Amperometric.png

  • From Transmit Side:
    • Current seen by TIA = (Step Voltage)/Z=  300mV/8.8kOhm = 34.09uA
    • 2K + 6.8K are 0.1% accurate.
  • From Receive Side:
    • Input Current Resolution = 3.6V/2^16   1/1.5  1/RTIA = 4.88nA (assumption RTIA=7.5k as on ADuCM350 Switch Mux Board)
    • Code Change in ADC = 32768 – 25790 = 6978 Codes
    • Current seen by TIA = Current Resolution X Code Change in ADC = 4.88nA * 6973 = 34.05uA
    • More accurate series resistors will give better accuracy etc.

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