System Setup
- Documentation:
- AN-1281
- Hardware
- Eval-ADuCM350EBZ
- ADuCM350 Switch Mux Config
- Software
- AmperometricMeasurement example in IAR Embedded Workbench
- View data in Comms port
Software Configuration for measuring R5 + R6 (10uF + 6.8 kOhm)
Black Text Is Original
Red Text is changes from Original
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.
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)
- 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=7.5kΩ 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.